Spring 之 BeanFactory 源码 - 抽象/类 分析
BeanFactory的基本类体系结构（类为主）：
上图可与 Spring源码分析——BeanFactory体系之接口详细分析 的图结合分析，一个以接口为主，一个以类为主
具体：
1、7层的类体系继承。
2、AbstractBeanFactory实现了最重要的ConfigurableBeanFactory接口，DefaultSingletonBeanRegistry实现了SingletonBeanRegistry单例类注册接口，SimpleAliasRegistry实现了AliasRegistry别名注册接口。
3、祖先类SimpleAliasRegistry、DefaultSingletonBeanRegistry和子孙类XmlBeanFactory、DefaultListableBeanFactory是完整的类，而中间的类FactoryBeanRegistrySupport、AbstractBeanFactory、AbstractAutowireCapableBeanFactory都是抽象类。
总结：
具体上来说，XmlBeanFactory光是父类就有6个了，加上自身，总共7层了。实际上分析接口结构就会看到，作为IOC类工厂而言，XmlBeanFactory的类体系结构实际是从祖先AbstractBeanFactory这个类开始的，因为是它实现了BeanFactory的子接口ConfigurableBeanFactory，虽然它继承自FactoryBeanRegistrySupport，但可以说这只是工厂功能的扩充，扩展了对工厂Bean以及工厂所产生的Bean的操作。
简单的别名注册器——SimpleAliasRegistry
上篇已经讲过AliasRegistry，非常简单的4个方法，体现了对别名注册的支持，而SimpleAliasRegistry就是它的简单实现。
源码：
1 public class SimpleAliasRegistry implements AliasRegistry {
2
3 /*
4 *用一个支持高并发的ConcurrentHashMap来放置所有的别名
5 */
6 private final Map<String, String> aliasMap = new ConcurrentHashMap<String, String>(
7 16);
8
9 // AliasRegistry的接口方法，注册别名。不允许重复注册。
10 public void registerAlias(String name, String alias) {
11 Assert.hasText(name, "'name' must not be empty");
12 Assert.hasText(alias, "'alias' must not be empty");
13 if (alias.equals(name)) {
14 this.aliasMap.remove(alias);
15 } else {
16 if (!allowAliasOverriding()) {
17 String registeredName = this.aliasMap.get(alias);
18 if (registeredName != null && !registeredName.equals(name)) {
19 throw new IllegalStateException("Cannot register alias '"
20 + alias + "' for name '" + name
21 + "': It is already registered for name '"
22 + registeredName + "'.");
23 }
24 }
25 checkForAliasCircle(name, alias);//alias不能等于name在map中最后的对应（详见checkForAliasCircle方法）
26 this.aliasMap.put(alias, name);//alias是key,name是value
27 }
28 }
29
30 /**
31 * 返回是否允许Alias重写，默认为允许
32 */
33 protected boolean allowAliasOverriding() {
34 return true;
35 }
36
37 // AliasRegistry的接口方法，移除别名，如果别名未注册，则抛出异常
38 public void removeAlias(String alias) {
39 String name = this.aliasMap.remove(alias);
40 if (name == null) {
41 throw new IllegalStateException("No alias '" + alias
42 + "' registered");
43 }
44 }
45
46 // AliasRegistry的接口方法，给定名称判断是否为别名
47 public boolean isAlias(String name) {
48 return this.aliasMap.containsKey(name);
49 }
50
51 // AliasRegistry的接口方法
52 public String[] getAliases(String name) {
53 List<String> result = new ArrayList<String>();
54 synchronized (this.aliasMap) {
55 retrieveAliases(name, result);
56 }
57 return StringUtils.toStringArray(result);
58 }
59
60 /*
61 * 找出名字说对应的所有别名。
62 */
63 private void retrieveAliases(String name, List<String> result) {
64 for (Map.Entry<String, String> entry : this.aliasMap.entrySet()) {//遍历aliasMap
65 String registeredName = entry.getValue();//取aliasMap的每个value
66 if (registeredName.equals(name)) {//如果value等于指定的这个name
67 String alias = entry.getKey();//取value对应的key
68 result.add(alias);//将alias加入
69 retrieveAliases(alias, result);//继续查看以alias为value的key
70 }
71 }
72 }
73
74 /*
75 * 处理所有的别名，如果处理正确，把原来的用解析后的替换
76 */
77 public void resolveAliases(StringValueResolver valueResolver) {
78 Assert.notNull(valueResolver, "StringValueResolver must not be null");
79 synchronized (this.aliasMap) {
80 Map<String, String> aliasCopy = new HashMap<String, String>(
81 this.aliasMap);
82 for (String alias : aliasCopy.keySet()) {
83 String registeredName = aliasCopy.get(alias);//取出key对应的value
84 String resolvedAlias = valueResolver.resolveStringValue(alias);//解析后的key
85 String resolvedName = valueResolver
86 .resolveStringValue(registeredName);//解析后的value
87 if (resolvedAlias.equals(resolvedName)) {//若解析后的key、name相等，就把它们从aliasMap中移除
88 this.aliasMap.remove(alias);
89 } else if (!resolvedAlias.equals(alias)) {//若解析后的key不等于原来的Key
90 String existingName = this.aliasMap.get(resolvedAlias);//取出解析后的key对应的value
91 if (existingName != null//如果不为空且不等于解析后的value，就抛出异常
92 && !existingName.equals(resolvedName)) {
93 throw new IllegalStateException(
94 "Cannot register resolved alias '"
95 + resolvedAlias
96 + "' (original: '"
97 + alias
98 + "') for name '"
99 + resolvedName
100 + "': It is already registered for name '"
101 + registeredName + "'.");
102 }
103 checkForAliasCircle(resolvedName, resolvedAlias);
104 this.aliasMap.remove(alias);
105 this.aliasMap.put(resolvedAlias, resolvedName);
106 } else if (!registeredName.equals(resolvedName)) {
107 this.aliasMap.put(alias, resolvedName);
108 }
109 }
110 }
111 }
112
113 /*
114 * 根据name这个Key，在aliasMap中不断循环的取对应的value，如果取得到，就继续根据这个value取值，不断循环继续。
115 * 直到取不到，就把这个在aliasMap中无对应值的key返回。
116 */
117 public String canonicalName(String name) {
118 String canonicalName = name; //规范名
119 // Handle aliasing...
120 String resolvedName;//已解析名
121 do {
122 resolvedName = this.aliasMap.get(canonicalName);//aliasMap中规范名对应的值赋值给已解析名
123 if (resolvedName != null) {//如果已解析名存在（即规范名在aliasMap中有对应的值）
124 canonicalName = resolvedName; // 这个已解析名赋值给标准名
125 }
126 } while (resolvedName != null);//不断循环，直到已解析名不存在
127 return canonicalName;
128 }
129
130 /*
131 * 如果别名alias等于canonicalName(name)就抛出异常
132 */
133 protected void checkForAliasCircle(String name, String alias) {
134 if (alias.equals(canonicalName(name))) {
135 throw new IllegalStateException("Cannot register alias '" + alias
136 + "' for name '" + name + "': Circular reference - '"
137 + name + "' is a direct or indirect alias for '" + alias
138 + "' already");
139 }
140 }
141
142 }
具体：
1、1个支持高并发的ConcurrentHashMap来放置所有的别名，其中key是别名，value是真名。
2、4个方法实现了SimpleAliasRegistry。
3、3个用来辅助实现4个接口方法的方法。其中canonicalName(String name)的实现非常优雅，用来循环来回判断，把aliasMap中无对应值的key返回。
4、2个添加额外功能的方法 retrieveAliases 和 resolveAliases ，前者是找出名字对应的所有别名，后者是用一个StringValueResolver处理解析所有的别名-名称。
总结：
这是一个非常简单的别名注册器，一个简单的接口实现。不过其中包含了非常优雅的方法实现，值得一看！
默认单例注册类——DefaultSingletonBeanRegistry
源码：
1 public class DefaultSingletonBeanRegistry extends SimpleAliasRegistry implements SingletonBeanRegistry {
2
3 protected static final Object NULL_OBJECT = new Object();//空object
4
5
6 /** Logger available to subclasses */
7 protected final Log logger = LogFactory.getLog(getClass());
8
9 /** 单例缓存: bean name --> bean instance */
10 private final Map<String, Object> singletonObjects = new ConcurrentHashMap<String, Object>(64);
11
12 /** 单例工厂缓存: bean name --> ObjectFactory */
13 private final Map<String, ObjectFactory> singletonFactories = new HashMap<String, ObjectFactory>(16);
14
15 /** 早期单例对象缓存: bean name --> bean instance */
16 private final Map<String, Object> earlySingletonObjects = new HashMap<String, Object>(16);
17
18 /** 注册过的单例类（单例工厂） */
19 private final Set<String> registeredSingletons = new LinkedHashSet<String>(64);
20
21 /** 即将创建的单例类 (using a ConcurrentHashMap as a Set) */
22 private final Map<String, Boolean> singletonsCurrentlyInCreation = new ConcurrentHashMap<String, Boolean>(16);
23
24 /** 正在创建的单例类 (using a ConcurrentHashMap as a Set) */
25 private final Map<String, Boolean> inCreationCheckExclusions = new ConcurrentHashMap<String, Boolean>(16);
26
27 /** 被压制的异常集合 */
28 private Set<Exception> suppressedExceptions;
29
30 /** 单例类是否真正被销毁 */
31 private boolean singletonsCurrentlyInDestruction = false;
32
33 /** Disposable接口的实例: bean name --> disposable instance */
34 private final Map<String, Object> = new LinkedHashMap<String, Object>();
35
36 /** bean名称和bean所有包含的Bean的名称的map: bean name --> Set of bean names that the bean contains */
37 private final Map<String, Set<String>> containedBeanMap = new ConcurrentHashMap<String, Set<String>>(16);
38
39 /** bean名称和所有依赖于Bean的名称的map: bean name --> Set of dependent bean names */
40 private final Map<String, Set<String>> dependentBeanMap = new ConcurrentHashMap<String, Set<String>>(64);
41
42 /** bean名称和bean所依赖的所有名称的map --> Set of bean names for the bean's dependencies */
43 private final Map<String, Set<String>> dependenciesForBeanMap = new ConcurrentHashMap<String, Set<String>>(64);
44
45 //SingletonBeanRegistry接口的实现类————注册单例Bean，不能重复注册
46 public void registerSingleton(String beanName, Object singletonObject) throws IllegalStateException {
47 Assert.notNull(beanName, "'beanName' must not be null");
48 synchronized (this.singletonObjects) {
49 Object oldObject = this.singletonObjects.get(beanName);
50 if (oldObject != null) {
51 throw new IllegalStateException("Could not register object [" + singletonObject +
52 "] under bean name '" + beanName + "': there is already object [" + oldObject + "] bound");
53 }
54 addSingleton(beanName, singletonObject);
55 }
56 }
57
58 //注册一个单例类，注册之后，从singletonFactories、earlySingletonObjects中删去
59 protected void addSingleton(String beanName, Object singletonObject) {
60 synchronized (this.singletonObjects) {
61 this.singletonObjects.put(beanName, (singletonObject != null ? singletonObject : NULL_OBJECT));
62 this.singletonFactories.remove(beanName);
63 this.earlySingletonObjects.remove(beanName);//
64 this.registeredSingletons.add(beanName);//加入，注册过的单例类集合
65 }
66 }
67
68 //注册一个单例工厂类，注册后从earlySingletonObjects移除
69 protected void addSingletonFactory(String beanName, ObjectFactory singletonFactory) {
70 Assert.notNull(singletonFactory, "Singleton factory must not be null");
71 synchronized (this.singletonObjects) {
72 if (!this.singletonObjects.containsKey(beanName)) { //单例工厂类不能和单例类同名
73 this.singletonFactories.put(beanName, singletonFactory);
74 this.earlySingletonObjects.remove(beanName);
75 this.registeredSingletons.add(beanName);
76 }
77 }
78 }
79
80 //SingletonBeanRegistry接口的实现类
81 public Object getSingleton(String beanName) {
82 return getSingleton(beanName, true);
83 }
84
85 //根据beanName返回单例类
86 protected Object getSingleton(String beanName, boolean allowEarlyReference) {
87 Object singletonObject = this.singletonObjects.get(beanName);
88 if (singletonObject == null && isSingletonCurrentlyInCreation(beanName)) { // 如果取不到，且该bean正在创建
89 synchronized (this.singletonObjects) {
90 singletonObject = this.earlySingletonObjects.get(beanName);
91 if (singletonObject == null && allowEarlyReference) { // 如果从早期单例缓存中获取不到，且允许早期引用
92 ObjectFactory singletonFactory = this.singletonFactories.get(beanName); // 那么就从单例工厂缓存中获取单例工厂
93 if (singletonFactory != null) { // 如果还是获取不到，就创建一个单例工厂，并把它放进早期单例缓存中，并返回
94 singletonObject = singletonFactory.getObject();
95 this.earlySingletonObjects.put(beanName, singletonObject);
96 this.singletonFactories.remove(beanName);
97 }
98 }
99 }
100 }
101 return (singletonObject != NULL_OBJECT ? singletonObject : null);
102 }
103
104 //获取指定的单例Bean，如果取不到就调用指定的singletonFactory的getObject来返回
105 public Object getSingleton(String beanName, ObjectFactory singletonFactory) {
106 Assert.notNull(beanName, "'beanName' must not be null");
107 synchronized (this.singletonObjects) {
108 Object singletonObject = this.singletonObjects.get(beanName);//从单例缓存中获取
109 if (singletonObject == null) {
110 if (this.singletonsCurrentlyInDestruction) {//如果单例类正在被销毁，就抛出异常
111 throw new BeanCreationNotAllowedException(beanName,
112 "Singleton bean creation not allowed while the singletons of this factory are in destruction " +
113 "(Do not request a bean from a BeanFactory in a destroy method implementation!)");
114 }
115 if (logger.isDebugEnabled()) {
116 logger.debug("Creating shared instance of singleton bean '" + beanName + "'");
117 }
118 //如果不在inCreationCheckExclusions中，且可以向singletonsCurrentlyInCreation中添加，就抛出异常
119 beforeSingletonCreation(beanName);
120 //是否有记录被压制的异常
121 boolean recordSuppressedExceptions = (this.suppressedExceptions == null);
122 if (recordSuppressedExceptions) {//如果没有记录，即没有被压制的异常，就创建被压制的异常容器
123 this.suppressedExceptions = new LinkedHashSet<Exception>();
124 }
125 try {
126 singletonObject = singletonFactory.getObject();//以上都没有异常产生，那么就从指定的facgtory中取
127 }
128 catch (BeanCreationException ex) {
129 if (recordSuppressedExceptions) {
130 for (Exception suppressedException : this.suppressedExceptions) {
131 ex.addRelatedCause(suppressedException);
132 }
133 }
134 throw ex;
135 }
136 finally {
137 if (recordSuppressedExceptions) {
138 this.suppressedExceptions = null;
139 }
140 afterSingletonCreation(beanName);
141 }
142 addSingleton(beanName, singletonObject);//取成功就放进singletonObjects中
143 }
144 return (singletonObject != NULL_OBJECT ? singletonObject : null);
145 }
146 }
147
148 //添加一个被压制的异常
149 protected void onSuppressedException(Exception ex) {
150 synchronized (this.singletonObjects) {
151 if (this.suppressedExceptions != null) {
152 this.suppressedExceptions.add(ex);
153 }
154 }
155 }
156
157 //根据名称移除本容器中缓存的对应的单例Bean，把对应的单例从Bean集合、单例工厂集合、早期单例对象集合、注册过的单例集合都统统移除
158 protected void removeSingleton(String beanName) {
159 synchronized (this.singletonObjects) {
160 this.singletonObjects.remove(beanName);
161 this.singletonFactories.remove(beanName);
162 this.earlySingletonObjects.remove(beanName);
163 this.registeredSingletons.remove(beanName);
164 }
165 }
166 //SingletonBeanRegistry接口的实现类
167 public boolean containsSingleton(String beanName) {
168 return (this.singletonObjects.containsKey(beanName));
169 }
170
171 //SingletonBeanRegistry接口的实现类
172 public String[] getSingletonNames() {
173 synchronized (this.singletonObjects) {
174 return StringUtils.toStringArray(this.registeredSingletons);
175 }
176 }
177 //SingletonBeanRegistry接口的实现类
178 public int getSingletonCount() {
179 synchronized (this.singletonObjects) {
180 return this.registeredSingletons.size();
181 }
182 }
183
184 // 设置某个Bean是否正在创建
185 public void setCurrentlyInCreation(String beanName, boolean inCreation) {
186 Assert.notNull(beanName, "Bean name must not be null");
187 if (!inCreation) {
188 this.inCreationCheckExclusions.put(beanName, Boolean.TRUE);
189 }
190 else {
191 this.inCreationCheckExclusions.remove(beanName);
192 }
193 }
194
195 //判断某个Bean是否正在被创建
196 public boolean isCurrentlyInCreation(String beanName) {
197 Assert.notNull(beanName, "Bean name must not be null");
198 return (!this.inCreationCheckExclusions.containsKey(beanName) && isActuallyInCreation(beanName));
199 }
200
201 protected boolean isActuallyInCreation(String beanName) {
202 return isSingletonCurrentlyInCreation(beanName);
203 }
204
205 //是否即将被创建
206 public boolean isSingletonCurrentlyInCreation(String beanName) {
207 return this.singletonsCurrentlyInCreation.containsKey(beanName);
208 }
209
210 //单例类创建开始之前调用
211 //如果不在正在创建的单例类集合中，且可以向即将创建的单例类中添加，就抛出异常
212 protected void beforeSingletonCreation(String beanName) {
213 if (!this.inCreationCheckExclusions.containsKey(beanName) &&
214 this.singletonsCurrentlyInCreation.put(beanName, Boolean.TRUE) != null) {
215 throw new BeanCurrentlyInCreationException(beanName);
216 }
217 }
218
219 //单例类创建之后调用
220 //如果不在正在创建的单例类中，也不在即将创建的单例类中移除失败，就抛出异常
221 protected void afterSingletonCreation(String beanName) {
222 if (!this.inCreationCheckExclusions.containsKey(beanName) &&
223 !this.singletonsCurrentlyInCreation.remove(beanName)) {
224 throw new IllegalStateException("Singleton '" + beanName + "' isn't currently in creation");
225 }
226 }
227
228 //往Disposable实例集合注册Disposable实例
229 public void registerDisposableBean(String beanName, DisposableBean bean) {
230 synchronized (this.disposableBeans) {
231 this.disposableBeans.put(beanName, bean);
232 }
233 }
234
235 //注册一个被包含的Bean和一个包含它的Bean（子->父）
236 public void registerContainedBean(String containedBeanName, String containingBeanName) {
237 synchronized (this.containedBeanMap) {
238 Set<String> containedBeans = this.containedBeanMap.get(containingBeanName);
239 if (containedBeans == null) {
240 containedBeans = new LinkedHashSet<String>(8);//containedBeans的初始容量为8
241 this.containedBeanMap.put(containingBeanName, containedBeans);//注意！containedBeanMap的Key是父bean，value是其所包含的所有子Bean（父->子）
242 }
243 containedBeans.add(containedBeanName);
244 }
245 registerDependentBean(containedBeanName, containingBeanName);//因为包含也是依赖的一种，所以此时也要注册在dependentBeanMap中
246 }
247
248 //给指定的Bean注册一个其依赖的Bean
249 public void registerDependentBean(String beanName, String dependentBeanName) {
250 String canonicalName = canonicalName(beanName);//在aliasMap中取规范名
251 synchronized (this.dependentBeanMap) { // 这里是注册依赖BeanMap，key是bean的名称，value是依赖这个bean的所有bean的名称
252 Set<String> dependentBeans = this.dependentBeanMap.get(canonicalName);
253 if (dependentBeans == null) {
254 dependentBeans = new LinkedHashSet<String>(8);//dependentBeans的初始容量也为8
255 this.dependentBeanMap.put(canonicalName, dependentBeans);//dependentBeanMap中Key为beanName的规范名，value是依赖它的所有Bean的名称
256 }
257 dependentBeans.add(dependentBeanName);
258 }
259 synchronized (this.dependenciesForBeanMap) { // 这里相反，注册的是某个Bean和其所依赖的Bean的集合，key是这个beanName，value是这个Bean的依赖的所有Bean的Name
260 Set<String> dependenciesForBean = this.dependenciesForBeanMap.get(dependentBeanName);
261 if (dependenciesForBean == null) {
262 dependenciesForBean = new LinkedHashSet<String>(8);
263 this.dependenciesForBeanMap.put(dependentBeanName, dependenciesForBean);
264 }
265 dependenciesForBean.add(canonicalName);
266 }
267 }
268
269 //判断某个Bean是否被其他Bean所依赖
270 protected boolean hasDependentBean(String beanName) {
271 return this.dependentBeanMap.containsKey(beanName);
272 }
273
274 //返回依赖于给定Bean的Bean名称的集合
275 public String[] getDependentBeans(String beanName) {
276 Set<String> dependentBeans = this.dependentBeanMap.get(beanName);
277 if (dependentBeans == null) {
278 return new String[0];
279 }
280 return StringUtils.toStringArray(dependentBeans);
281 }
282
283 //返回某个Bean所依赖的所有Bean的名称
284 public String[] getDependenciesForBean(String beanName) {
285 Set<String> dependenciesForBean = this.dependenciesForBeanMap.get(beanName);
286 if (dependenciesForBean == null) {
287 return new String[0];
288 }
289 return dependenciesForBean.toArray(new String[dependenciesForBean.size()]);
290 }
291
292 //这个方法居然连注释都没有？太奇怪了！
293 public void destroySingletons() {
294 if (logger.isInfoEnabled()) {
295 logger.info("Destroying singletons in " + this);
296 }
297 synchronized (this.singletonObjects) {//首先标记，所有的单例Bean正在被销毁，那么getSingleton就无法获得单例Bean了
298 this.singletonsCurrentlyInDestruction = true;
299 }
300
301 String[] disposableBeanNames;
302 synchronized (this.disposableBeans) {//然后把所有的disposableBean都放进数组，一个个按名称销毁
303 disposableBeanNames = StringUtils.toStringArray(this.disposableBeans.keySet());
304 }
305 for (int i = disposableBeanNames.length - 1; i >= 0; i--) {
306 destroySingleton(disposableBeanNames[i]);
307 }
308 // 把本容器的所有的包含关系、依赖关系、被依赖关系的集合全部清空
309 this.containedBeanMap.clear();
310 this.dependentBeanMap.clear();
311 this.dependenciesForBeanMap.clear();
312
313 //然后把本容器的所有其他集合全部清空
314 synchronized (this.singletonObjects) {
315 this.singletonObjects.clear();
316 this.singletonFactories.clear();
317 this.earlySingletonObjects.clear();
318 this.registeredSingletons.clear();
319 this.singletonsCurrentlyInDestruction = false;
320 }
321 }
322
323 //销毁某个单例Bean
324 public void destroySingleton(String beanName) {
325 // Remove a registered singleton of the given name, if any.
326 removeSingleton(beanName);//先把它销毁
327
328 DisposableBean disposableBean;//它相应的DisposableBean实例
329 synchronized (this.disposableBeans) {
330 disposableBean = (DisposableBean) this.disposableBeans.remove(beanName);//从disposableBeans移除这个实例
331 }
332 destroyBean(beanName, disposableBean);
333 }
334
335 // 销毁指定名称的Bean，且销毁依赖于它的所有Bean
336 protected void destroyBean(String beanName, DisposableBean bean) {
337 // 首先销毁依赖它的所有Bean
338 Set<String> dependencies = this.dependentBeanMap.remove(beanName);//取依赖于指定Bean的所有Bean
339 if (dependencies != null) {
340 if (logger.isDebugEnabled()) {
341 logger.debug("Retrieved dependent beans for bean '" + beanName + "': " + dependencies);
342 }
343 for (String dependentBeanName : dependencies) {
344 destroySingleton(dependentBeanName);//一个个销毁
345 }
346 }
347
348 // 然后销毁它
349 if (bean != null) {
350 try {
351 bean.destroy();
352 }
353 catch (Throwable ex) {
354 logger.error("Destroy method on bean with name '" + beanName + "' threw an exception", ex);
355 }
356 }
357
358 // 然后销毁它所包含的Bean
359 Set<String> containedBeans = this.containedBeanMap.remove(beanName);
360 if (containedBeans != null) {
361 for (String containedBeanName : containedBeans) {
362 destroySingleton(containedBeanName);
363 }
364 }
365
366 // 然后把所有它依赖的Bean的依赖关系删除，首先删除dependentBeanMap中的依赖关系
367 synchronized (this.dependentBeanMap) {
368 //这样的for循环用法实在是经典
369 for (Iterator<Map.Entry<String, Set<String>>> it = this.dependentBeanMap.entrySet().iterator(); it.hasNext();) {
370 Map.Entry<String, Set<String>> entry = it.next();
371 Set<String> dependenciesToClean = entry.getValue();
372 dependenciesToClean.remove(beanName);
373 if (dependenciesToClean.isEmpty()) {
374 it.remove();
375 }
376 }
377 }
378
379 // 然后删除dependenciesForBeanMap中的依赖关系
380 this.dependenciesForBeanMap.remove(beanName);
381 }
382
383 /**
384 * Expose the singleton mutex to subclasses.
385 * <p>Subclasses should synchronize on the given Object if they perform
386 * any sort of extended singleton creation phase. In particular, subclasses
387 * should <i>not</i> have their own mutexes involved in singleton creation,
388 * to avoid the potential for deadlocks in lazy-init situations.
389 */
390 //返回子类单例类的互斥体？这个暂且放着。
391 protected final Object getSingletonMutex() {
392 return this.singletonObjects;
393 }
394
395 }
具体：
1、一个静态不可变的空对象NULL_OBJECT、一个简单的日志对象。
2、本类有如下集合：
（1）、一个单例缓存集合——singletonObjects
（2）、一个单例工厂缓存集合——singletonFactories
（3）、一个早期单例对象缓存集合——earlySingletonObjects
（4）、一个注册过的单例类（单例工厂）集合——registeredSingletons
（5）、一个即将创建的单例类集合——singletonsCurrentlyInCreation
（6）、一个正在创建的单例类集合——inCreationCheckExclusions
（7）、一个被压制的异常集合——suppressedExceptions（这种设计模式实在是经典！）
（8）、一个判断所有单例类是否马上被销毁的标记——singletonsCurrentlyInDestruction
（9）、一个Disposable接口（即可以自定义回收资源的接口）实例的集合——disposableBeans
（10）、一个bean名称和bean所有包含的Bean的名称的集合——containedBeanMap
（11）、bean名称和所有依赖于Bean的名称的集合——dependentBeanMap
（12）、bean名称和bean所依赖的所有名称的集合——dependenciesForBeanMap
3、2个注册单例方法，实际是暴露在外的SingletonBeanRegistry接口的实现方法registerSingleton加锁后调用另一个addSingleton方法。
4、1个注册单例工厂的方法。单例工厂类不能和单例类同名。
5、3个获取单例类的方法。一种是从单例类集合中获取，如果获取不到，boolean控制要么返回空对象，要么返回一个单例工厂。另一种是从单例集合中获取，如果取不到，就从指定的工厂中获取。还有一种？呵，就是暴露在外的SingletonBeanRegistry接口方法呗，直接调用第一种。
6、1个添加被压制的异常集合中添加异常的方法，我觉得这个设计非常经典。但需要记录异常，却不想处理的时候，可以采用这种设计模式。
7、1个移除单例的方法、1个判断是否包含单例的方法、1个返回所有单例名数组的方法、1个返回单例总数目的方法。
8、1个设置某个Bean是否正在创建的方法、1个判断某个Bean是否正在被创建的方法、2个判断某个Bean是否即将被创建的方法（一个调用另一个，用于重写）。
9、1个单例类创建开始之前调用的方法、1个单单例类创建之后调用的方法
10、1个往Disposable实例集合注册Disposable实例的方法，这个是Bean销毁前的准备。
11、1个注册一个被包含的Bean和一个包含的Bean的名称到containedBeanMap集合的方法。这个方法设置了Bean之间的包含关系。
12、1个给指定的Bean注册一个其依赖的Bean的方法。这个方法设置了Bean自己的依赖关系。
13、1个判断是否被依赖的方法、1个返回给定Bean名称的所有依赖的数组的方法、1个返回依赖于给定Bean的所有Bean名的数组的方法。
14、1个销毁所有单例类的方法（这个方法居然完全没有注释，有没搞错！）、1个销毁某个单例的方法、1个// 销毁指定名称的Bean，且销毁依赖于它的所有Bean的方法。
15、1个返回子类单例类的互斥体的方法。这个暂且待下一篇分析子类再看。
总结：
类如其名，默认的单例注册器。这个工厂的写法实在功能丰富，为了监控到一个单例类构建过程中的方方面面，简直就是不择手段啊，居然准备了12个集合，除了一个一个被压制的异常集合，其余全是跟单例类有直接关系的。可以说，这个单例注册器监听、实现了Spring单例注册的各个过程，具体的解读分析，在上面的源代码中可以看到，读者阅读我注释过的源代码应该会很轻松。
工厂Bean注册支持——FactoryBeanRegistrySupport
废话不多说，直接看我注释的源码：
/*
* Copyright 2002-2012 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/ package org.springframework.beans.factory.support; import java.security.AccessControlContext;
import java.security.AccessController;
import java.security.PrivilegedAction;
import java.security.PrivilegedActionException;
import java.security.PrivilegedExceptionAction;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap; import org.springframework.beans.BeansException;
import org.springframework.beans.factory.BeanCreationException;
import org.springframework.beans.factory.BeanCurrentlyInCreationException;
import org.springframework.beans.factory.FactoryBean;
import org.springframework.beans.factory.FactoryBeanNotInitializedException; /**
* Support base class for singleton registries which need to handle
* {@link org.springframework.beans.factory.FactoryBean} instances,
* integrated with {@link DefaultSingletonBeanRegistry}'s singleton management.
*
* <p>Serves as base class for {@link AbstractBeanFactory}.
*
* @author Juergen Hoeller
* @since 2.5.1
*/
public abstract class FactoryBeanRegistrySupport extends DefaultSingletonBeanRegistry { /** 工厂Bean生产的单例的集合: FactoryBean name --> object */
private final Map<String, Object> factoryBeanObjectCache = new ConcurrentHashMap<String, Object>(16); //返回指定FactoryBean的类型
protected Class getTypeForFactoryBean(final FactoryBean factoryBean) {
try {
if (System.getSecurityManager() != null) {//如果当前系统存在安全管理器
return AccessController.doPrivileged(new PrivilegedAction<Class>() {//那么返回factoryBean的类型这个操作不做权限检查，直接调用
public Class run() {
return factoryBean.getObjectType();
}
}, getAccessControlContext());
}
else {//不存在安全管理器，就直接调用！
return factoryBean.getObjectType();
}
}
catch (Throwable ex) {
logger.warn("FactoryBean threw exception from getObjectType, despite the contract saying " +
"that it should return null if the type of its object cannot be determined yet", ex);
return null;
}
} //根据FactoryBean名，返回其生产的Object，从缓存中取
protected Object getCachedObjectForFactoryBean(String beanName) {
Object object = this.factoryBeanObjectCache.get(beanName);
return (object != NULL_OBJECT ? object : null);
} //从工厂Bean中取实例，实际调用下面的doGetObjectFromFactoryBean方法。
protected Object getObjectFromFactoryBean(FactoryBean factory, String beanName, boolean shouldPostProcess) {
if (factory.isSingleton() && containsSingleton(beanName)) {//若工厂是单例，且本容器包含beanName对应的单例类
synchronized (getSingletonMutex()) {//以所有的单例集合为锁
Object object = this.factoryBeanObjectCache.get(beanName);//根据beanName从factoryBeanObjectCache中取
if (object == null) {//若取不到
object = doGetObjectFromFactoryBean(factory, beanName, shouldPostProcess);
this.factoryBeanObjectCache.put(beanName, (object != null ? object : NULL_OBJECT));//放进factoryBeanObjectCache
}
return (object != NULL_OBJECT ? object : null);
}
}
else {//否则，直接
return doGetObjectFromFactoryBean(factory, beanName, shouldPostProcess);
}
} //从工厂Bean中取实例
private Object doGetObjectFromFactoryBean(
final FactoryBean factory, final String beanName, final boolean shouldPostProcess)
throws BeanCreationException { Object object;
//跟getTypeForFactoryBean的实现一样。
try {
if (System.getSecurityManager() != null) {//若系统存在安全管理器
AccessControlContext acc = getAccessControlContext();//得到当前容器的安全访问上下文
try {//返回factoryBean的类型这个操作不做权限检查，直接调用
object = AccessController.doPrivileged(new PrivilegedExceptionAction<Object>() {
public Object run() throws Exception {
return factory.getObject();
}
}, acc);
}
catch (PrivilegedActionException pae) {
throw pae.getException();
}
}
else {//否则直接取
object = factory.getObject();
}
}
catch (FactoryBeanNotInitializedException ex) {
throw new BeanCurrentlyInCreationException(beanName, ex.toString());
}
catch (Throwable ex) {
throw new BeanCreationException(beanName, "FactoryBean threw exception on object creation", ex);
} //如果从beanFactory取不到，且这个实例即将被创建，抛出异常
if (object == null && isSingletonCurrentlyInCreation(beanName)) {
throw new BeanCurrentlyInCreationException(
beanName, "FactoryBean which is currently in creation returned null from getObject");
}
//若取不到，且这个实例允许前处理
if (object != null && shouldPostProcess) {
try {
object = postProcessObjectFromFactoryBean(object, beanName);//这里简单返回，前处理的功能留给子类重写
}
catch (Throwable ex) {
throw new BeanCreationException(beanName, "Post-processing of the FactoryBean's object failed", ex);
}
} return object;
} //这里简单返回Object，留给子类重写
protected Object postProcessObjectFromFactoryBean(Object object, String beanName) throws BeansException {
return object;
} //如果这个Object是FactoryBean类型，就转换成FactoryBean返回
protected FactoryBean getFactoryBean(String beanName, Object beanInstance) throws BeansException {
if (!(beanInstance instanceof FactoryBean)) {
throw new BeanCreationException(beanName,
"Bean instance of type [" + beanInstance.getClass() + "] is not a FactoryBean");
}
return (FactoryBean) beanInstance;
} //移除单例类这个方法重写，父类的移除之外，还要移除factoryBeanObjectCache中的。
@Override
protected void removeSingleton(String beanName) {
super.removeSingleton(beanName);
this.factoryBeanObjectCache.remove(beanName);
} //返回当前容器的安全访问上下文
protected AccessControlContext getAccessControlContext() {
return AccessController.getContext();
} }
具体：
1、1个不可变的实例属性ConcurrentHashMap来存放工厂Bean生产的单例的集合：FactoryBean name --> object。
2、1个方法返回指定FactoryBean的类型的方法。
3、1个根据FactoryBean名，返回其生产的Object的方法。
4、2个从工厂Bean中取实例的方法。实际是一个方法调用另一个，取不到则返回空。
5、1个postProcessObjectFromFactoryBean的方法，留给子类重写。
6、1个取工厂Bean的方法——如果这个Object是FactoryBean类型，就转换成FactoryBean返回
7、1个重写父类的removeSingleton方法，移除单例的时候，父类的移除之外，还要移除factoryBeanObjectCache中的。
8、1个返回当前容器的安全访问上下文的方法。
总结：
这个类FactoryBeanRegistrySupport，类如其名，实现了对工厂Bean注册的支持。值得注意的是，这个类有较多类似如下的写法：
if (System.getSecurityManager() != null) {//如果当前系统存在安全管理器
return AccessController.doPrivileged(new PrivilegedAction<Class>() {
public Class run() {
//实际处理
}
}, getAccessControlContext());
}
else {//不存在安全管理器，就直接调用！
//实际处理
}
这个方法的意思是，如果当前系统存在安全管理器，那么接下来的操作不做权限检查，直接调用。而如果不存在，OK，那当然是直接调用了。这是JDK层面的一个系统安全管理工具，某些情况下，可以避免系统进行安全检查。这里稍作了解即可。在学习JVM的时候可仔细了解原理。
除此之外，这里可以了解一下这个类比较重要的方法doGetObjectFromFactoryBean，是从工厂Bean中取实例的方法，源码已经给出，这里重点指出一下，不必折叠了：
//从工厂Bean中取实例，shouldPostProcess指的是是否允许提前处理
private Object doGetObjectFromFactoryBean(
final FactoryBean factory, final String beanName, final boolean shouldPostProcess)
throws BeanCreationException { Object object;
//跟getTypeForFactoryBean的实现一样。
try {
if (System.getSecurityManager() != null) {//若系统存在安全管理器
AccessControlContext acc = getAccessControlContext();//得到当前容器的安全访问上下文
try {//返回factoryBean的类型这个操作不做权限检查，直接调用
object = AccessController.doPrivileged(new PrivilegedExceptionAction<Object>() {
public Object run() throws Exception {
return factory.getObject();
}
}, acc);
}
catch (PrivilegedActionException pae) {
throw pae.getException();
}
}
else {//否则直接取
object = factory.getObject();
}
}
catch (FactoryBeanNotInitializedException ex) {
throw new BeanCurrentlyInCreationException(beanName, ex.toString());
}
catch (Throwable ex) {
throw new BeanCreationException(beanName, "FactoryBean threw exception on object creation", ex);
} //如果从beanFactory取不到，且这个实例即将被创建，抛出异常
if (object == null && isSingletonCurrentlyInCreation(beanName)) {
throw new BeanCurrentlyInCreationException(
beanName, "FactoryBean which is currently in creation returned null from getObject");
}
//若取不到，并非即将创建、且这个实例允许前处理
if (object != null && shouldPostProcess) {
try {
object = postProcessObjectFromFactoryBean(object, beanName);//这里简单返回，前处理的功能留给子类重写
}
catch (Throwable ex) {
throw new BeanCreationException(beanName, "Post-processing of the FactoryBean's object failed", ex);
}
} return object;
}
相信上面已经解释的很清楚了。
最重要的抽象类——AbstractBeanFactory
（PS：这个类的方法实在是多的骇人，看得我实在是头都大了。不多看到后面，发现很多方法其实也就是那么回事。源码注释了大部分，且看看咯！）
public abstract class AbstractBeanFactory extends FactoryBeanRegistrySupport implements ConfigurableBeanFactory {
//父工厂的引用
private BeanFactory parentBeanFactory;
//类加载器
private ClassLoader beanClassLoader = ClassUtils.getDefaultClassLoader();
//临时类加载器
private ClassLoader tempClassLoader;
/** Whether to cache bean metadata or rather reobtain it for every access */
private boolean cacheBeanMetadata = true;
//Bean表达式分解器，用来分解Bean定义中的表达式
private BeanExpressionResolver beanExpressionResolver;
//转换服务，用来替代属性编辑器的
private ConversionService conversionService;
//属性编辑登记员集合，容量为4的LinkedHashSet
private final Set<PropertyEditorRegistrar> propertyEditorRegistrars =
new LinkedHashSet<PropertyEditorRegistrar>(4);
//通用的类型转换器，重写了默认的属相编辑器机制
private TypeConverter typeConverter;
//默认的属性编辑器集合
private final Map<Class<?>, Class<? extends PropertyEditor>> customEditors =
new HashMap<Class<?>, Class<? extends PropertyEditor>>(4);
//嵌入值转换器集合
private final List<StringValueResolver> embeddedValueResolvers = new LinkedList<StringValueResolver>();
//BeanPostProcessor处理器集合
private final List<BeanPostProcessor> beanPostProcessors = new ArrayList<BeanPostProcessor>();
//标记是否有InstantiationAwareBeanPostProcessors实例被注册
private boolean hasInstantiationAwareBeanPostProcessors;
//标记是否有DestructionAwareBeanPostProcessors实例被注册
private boolean hasDestructionAwareBeanPostProcessors;
//范围标识符和Scope实例的对应的Map
private final Map<String, Scope> scopes = new HashMap<String, Scope>(8);
//安全上下文Provider，可以得到安全管理器的安全上下文
private SecurityContextProvider securityContextProvider;
//合并后的Bean根定义的集合
private final Map<String, RootBeanDefinition> mergedBeanDefinitions =
new ConcurrentHashMap<String, RootBeanDefinition>(64);
//至少被创建过一次的Bean的集合
private final Map<String, Boolean> alreadyCreated = new ConcurrentHashMap<String, Boolean>(64);
//当前正在创建的原型，当前线程相关
private final ThreadLocal<Object> prototypesCurrentlyInCreation =
new NamedThreadLocal<Object>("Prototype beans currently in creation");
//空构造方法
public AbstractBeanFactory() {
}
//指定父Bean工厂的构造方法
public AbstractBeanFactory(BeanFactory parentBeanFactory) {
this.parentBeanFactory = parentBeanFactory;
}
//---------------------------------------------------------------------
// 3个getBean，BeanFactory接口的实现方法，实质是在调用doGetBean
//---------------------------------------------------------------------
public Object getBean(String name) throws BeansException {
return doGetBean(name, null, null, false);
}
public <T> T getBean(String name, Class<T> requiredType) throws BeansException {
return doGetBean(name, requiredType, null, false);
}
public Object getBean(String name, Object... args) throws BeansException {
return doGetBean(name, null, args, false);
}
// 提供创建时需要参数列表的getBean
public <T> T getBean(String name, Class<T> requiredType, Object... args) throws BeansException {
return doGetBean(name, requiredType, args, false);
}
//从容器中获取bean的基本方法。
@SuppressWarnings("unchecked")
protected <T> T doGetBean(
final String name, final Class<T> requiredType, final Object[] args, boolean typeCheckOnly)
throws BeansException {
final String beanName = transformedBeanName(name);//在aliasMap中取得的标准名
Object bean;
// Eagerly check singleton cache for manually registered singletons.
Object sharedInstance = getSingleton(beanName);//首先在单例集合中取
if (sharedInstance != null && args == null) {//如果取得到，没有指定参数
if (logger.isDebugEnabled()) {//若Log允许调试
if (isSingletonCurrentlyInCreation(beanName)) {//若正准备创建，输出日志
logger.debug("Returning eagerly cached instance of singleton bean '" + beanName +
"' that is not fully initialized yet - a consequence of a circular reference");
}
else {
logger.debug("Returning cached instance of singleton bean '" + beanName + "'");
}
}
////根据给定的实例是否为工厂Bean，返回它自己或工厂Bean创建的实例
bean = getObjectForBeanInstance(sharedInstance, name, beanName, null);
}
else {
if (isPrototypeCurrentlyInCreation(beanName)) {//如果正在被创建，就抛出异常
throw new BeanCurrentlyInCreationException(beanName);
}
BeanFactory parentBeanFactory = getParentBeanFactory();//取本容器的父容器
if (parentBeanFactory != null && !containsBeanDefinition(beanName)) {//若存在父容器，且本容器不存在对应的Bean定义
String nameToLookup = originalBeanName(name);//取原始的Bean名
if (args != null) {//若参数列表存在
// 那么用父容器根据原始Bean名和参数列表返回
return (T) parentBeanFactory.getBean(nameToLookup, args);
}
else {
// 参数列表不要求，那就直接根据原始名称和要求的类型返回
return parentBeanFactory.getBean(nameToLookup, requiredType);
}
}
//如果不需要类型检查，标记其已经被创建
if (!typeCheckOnly) {
markBeanAsCreated(beanName);
}
//根据beanName取其根Bean定义
final RootBeanDefinition mbd = getMergedLocalBeanDefinition(beanName);
checkMergedBeanDefinition(mbd, beanName, args);
String[] dependsOn = mbd.getDependsOn();//得到这个根定义的所有依赖
if (dependsOn != null) {
for (String dependsOnBean : dependsOn) {
getBean(dependsOnBean);//注册这个Bean
//注册一个Bean和依赖于它的Bean（后参数依赖前参数）
registerDependentBean(dependsOnBean, beanName);
}
}
// 如果Bean定义是单例，就在返回单例
if (mbd.isSingleton()) {
sharedInstance = getSingleton(beanName, new ObjectFactory<Object>() {
public Object getObject() throws BeansException {
try {
return createBean(beanName, mbd, args);
}
catch (BeansException ex) {
destroySingleton(beanName);
throw ex;
}
}
});
//根据给定的实例是否为工厂Bean，返回它自己或工厂Bean创建的实例
bean = getObjectForBeanInstance(sharedInstance, name, beanName, mbd);
}
//如果是原型
else if (mbd.isPrototype()) {
// It's a prototype -> create a new instance.
Object prototypeInstance = null;
try {
beforePrototypeCreation(beanName);//原型创建前，与当前线程绑定
prototypeInstance = createBean(beanName, mbd, args);
}
finally {
afterPrototypeCreation(beanName);//原型创建后，与当前线程解除绑定
}
bean = getObjectForBeanInstance(prototypeInstance, name, beanName, mbd);
}
else {//既不是单例又不是原型的情况
String scopeName = mbd.getScope();
final Scope scope = this.scopes.get(scopeName);//得到范围
if (scope == null) {
throw new IllegalStateException("No Scope registered for scope '" + scopeName + "'");
}
try {//根据范围创建实例
Object scopedInstance = scope.get(beanName, new ObjectFactory<Object>() {
public Object getObject() throws BeansException {
beforePrototypeCreation(beanName);
try {
return createBean(beanName, mbd, args);//原型创建前，与当前线程绑定
}
finally {
////原型创建后，与当前线程解除绑定
afterPrototypeCreation(beanName);
}
}
});
//根据给定的实例是否为工厂Bean，返回它自己或工厂Bean创建的实例
bean = getObjectForBeanInstance(scopedInstance, name, beanName, mbd);
}
catch (IllegalStateException ex) {
throw new BeanCreationException(beanName,
"Scope '" + scopeName + "' is not active for the current thread; " +
"consider defining a scoped proxy for this bean if you intend to refer to it from a singleton",
ex);
}
}
}
//判断要求的类型是否和Bean实例的类型正在匹配
if (requiredType != null && bean != null && !requiredType.isAssignableFrom(bean.getClass())) {
try {
return getTypeConverter().convertIfNecessary(bean, requiredType);//转换类型，不抛出异常就说明类型匹配
}
catch (TypeMismatchException ex) {
if (logger.isDebugEnabled()) {
logger.debug("Failed to convert bean '" + name + "' to required type [" +
ClassUtils.getQualifiedName(requiredType) + "]", ex);
}
throw new BeanNotOfRequiredTypeException(name, requiredType, bean.getClass());
}
}
return (T) bean;
}
//判断本容器是否包含指定bean
public boolean containsBean(String name) {
String beanName = transformedBeanName(name);
// （如果是否包含单例 或 包含Bean定义）且 （为工厂Bean的产物 或 本身就是工厂bean），就返回true
if (containsSingleton(beanName) || containsBeanDefinition(beanName)) {
return (!BeanFactoryUtils.isFactoryDereference(name) || isFactoryBean(name));
}
// 如果不包含单例且不包含Bean定义，就从父类去查找
BeanFactory parentBeanFactory = getParentBeanFactory();
return (parentBeanFactory != null && parentBeanFactory.containsBean(originalBeanName(name)));
}
//判断指定Bean是否为单例
public boolean isSingleton(String name) throws NoSuchBeanDefinitionException {
String beanName = transformedBeanName(name);
Object beanInstance = getSingleton(beanName, false);//首先从单例集合中取
if (beanInstance != null) {//取不到，就判断它是不是FactoryBean的实例
if (beanInstance instanceof FactoryBean) { // 如果是，要求它是工厂Bean产生的实例或这个工厂bean是单例
return (BeanFactoryUtils.isFactoryDereference(name) || ((FactoryBean<?>) beanInstance).isSingleton());
}
else {// 如果不是，要求它不是工厂Bean产生的实例
return !BeanFactoryUtils.isFactoryDereference(name);
}
}//若虽然取不到，但是单例集合中包含它的名字，说明它是单例
else if (containsSingleton(beanName)) {
return true;
}
else {
//从父工厂中去查询Bean定义
BeanFactory parentBeanFactory = getParentBeanFactory();
if (parentBeanFactory != null && !containsBeanDefinition(beanName)) {
//父工厂找不到Bean定义，那就在父工厂根据原始名去查是否为单例
return parentBeanFactory.isSingleton(originalBeanName(name));
}
//返回一个合并后的根Bean定义
RootBeanDefinition mbd = getMergedLocalBeanDefinition(beanName);
// In case of FactoryBean, return singleton status of created object if not a dereference.
//若该根定义是单例
if (mbd.isSingleton()) {
if (isFactoryBean(beanName, mbd)) { //若该根定义为工厂Bean
if (BeanFactoryUtils.isFactoryDereference(name)) {//判断是否为工厂产生的实例
return true;
}
//取对应的工厂，判断该工厂Bean是否为单例
FactoryBean<?> factoryBean = (FactoryBean<?>) getBean(FACTORY_BEAN_PREFIX + beanName);
return factoryBean.isSingleton();
}
else { // 是否不为工厂Bean产生的实例（此时，即，该根定义不为工厂Bean，且不为工厂Bean产生的实例的时候，由于根定义是单例，那么它就是单例）
return !BeanFactoryUtils.isFactoryDereference(name);
}
}
else {
return false;
}
}
}
//判断是否为原型
public boolean isPrototype(String name) throws NoSuchBeanDefinitionException {
String beanName = transformedBeanName(name);
BeanFactory parentBeanFactory = getParentBeanFactory();//得到父工厂
//若父工厂中的定义为原型，就为原型
if (parentBeanFactory != null && !containsBeanDefinition(beanName)) {
return parentBeanFactory.isPrototype(originalBeanName(name));
}
//若合并后的根定义为原型，且不是工厂Bean产生的实例、或本身是工厂Bean，那么就为原型
RootBeanDefinition mbd = getMergedLocalBeanDefinition(beanName);
if (mbd.isPrototype()) {
return (!BeanFactoryUtils.isFactoryDereference(name) || isFactoryBean(beanName, mbd));
}
else {
if (BeanFactoryUtils.isFactoryDereference(name)) {//若为工厂Bean产生的实例
return false;
}
if (isFactoryBean(beanName, mbd)) {//若为工厂Bean，取它产生的Bean，判断SmartFactoryBean
final FactoryBean<?> factoryBean = (FactoryBean<?>) getBean(FACTORY_BEAN_PREFIX + beanName);
if (System.getSecurityManager() != null) {
return AccessController.doPrivileged(new PrivilegedAction<Boolean>() {
public Boolean run() {
return ((factoryBean instanceof SmartFactoryBean && ((SmartFactoryBean<?>) factoryBean).isPrototype()) ||
!factoryBean.isSingleton());
}
}, getAccessControlContext());
}
else {
return ((factoryBean instanceof SmartFactoryBean && ((SmartFactoryBean<?>) factoryBean).isPrototype()) ||
!factoryBean.isSingleton());
}
}
else {
return false;
}
}
}
//判断类型是否匹配
public boolean isTypeMatch(String name, Class<?> targetType) throws NoSuchBeanDefinitionException {
String beanName = transformedBeanName(name);
Class<?> typeToMatch = (targetType != null ? targetType : Object.class);
Object beanInstance = getSingleton(beanName, false);//取name对应的单例
if (beanInstance != null) {
if (beanInstance instanceof FactoryBean) {//若为工厂Bean
//若不是工厂Bean产生的实例
if (!BeanFactoryUtils.isFactoryDereference(name)) {
//取工厂Bean的类型与targetType进行对比
Class<?> type = getTypeForFactoryBean((FactoryBean<?>) beanInstance);
return (type != null && ClassUtils.isAssignable(typeToMatch, type));
}
else {
return ClassUtils.isAssignableValue(typeToMatch, beanInstance);
}
}
//不是工厂Bean，那就直接判断
else {
return !BeanFactoryUtils.isFactoryDereference(name) &&
ClassUtils.isAssignableValue(typeToMatch, beanInstance);
}
}
//单例表中，对应的Key没有值，也不包含Bean定义，说明没有注册，返回false
else if (containsSingleton(beanName) && !containsBeanDefinition(beanName)) {
return false;
}
//以下是包含Bean定义的情况
else {
//先查父类的Bean定义
BeanFactory parentBeanFactory = getParentBeanFactory();
if (parentBeanFactory != null && !containsBeanDefinition(beanName)) {
// No bean definition found in this factory -> delegate to parent.
return parentBeanFactory.isTypeMatch(originalBeanName(name), targetType);
}
//直接查合并后的根定义
RootBeanDefinition mbd = getMergedLocalBeanDefinition(beanName);
//构建类型数组
Class[] typesToMatch = (FactoryBean.class.equals(typeToMatch) ?
new Class[] {typeToMatch} : new Class[] {FactoryBean.class, typeToMatch});
// Check decorated bean definition, if any: We assume it'll be easier
// to determine the decorated bean's type than the proxy's type.
//得到Bean定义的持有者
BeanDefinitionHolder dbd = mbd.getDecoratedDefinition();
if (dbd != null && !BeanFactoryUtils.isFactoryDereference(name)) {//若为Bean工厂生成的实例，先得到根定义
RootBeanDefinition tbd = getMergedBeanDefinition(dbd.getBeanName(), dbd.getBeanDefinition(), mbd);
Class<?> targetClass = predictBeanType(dbd.getBeanName(), tbd, typesToMatch);//得到预测的根定义
if (targetClass != null && !FactoryBean.class.isAssignableFrom(targetClass)) {
return typeToMatch.isAssignableFrom(targetClass);
}
}
Class<?> beanType = predictBeanType(beanName, mbd, typesToMatch);//预测后的类型
if (beanType == null) {
return false;
}
if (FactoryBean.class.isAssignableFrom(beanType)) {//BeanFactory是否为其子类
if (!BeanFactoryUtils.isFactoryDereference(name)) {//若不为工厂Bean的产物
// If it's a FactoryBean, we want to look at what it creates, not the factory class.
beanType = getTypeForFactoryBean(beanName, mbd);
if (beanType == null) {
return false;
}
}
}
else if (BeanFactoryUtils.isFactoryDereference(name)) {//若为工厂类Bean的产物
beanType = predictBeanType(beanName, mbd, FactoryBean.class);//预测类型
if (beanType == null || !FactoryBean.class.isAssignableFrom(beanType)) {
return false;
}
}
return typeToMatch.isAssignableFrom(beanType);
}
}
//返回类型
public Class<?> getType(String name) throws NoSuchBeanDefinitionException {
String beanName = transformedBeanName(name);
// Check manually registered singletons.
Object beanInstance = getSingleton(beanName, false);
if (beanInstance != null) {
if (beanInstance instanceof FactoryBean && !BeanFactoryUtils.isFactoryDereference(name)) {
return getTypeForFactoryBean((FactoryBean<?>) beanInstance);
}
else {
return beanInstance.getClass();
}
}
else if (containsSingleton(beanName) && !containsBeanDefinition(beanName)) {
// null instance registered
return null;
}
else {
// No singleton instance found -> check bean definition.
BeanFactory parentBeanFactory = getParentBeanFactory();
if (parentBeanFactory != null && !containsBeanDefinition(beanName)) {
// No bean definition found in this factory -> delegate to parent.
return parentBeanFactory.getType(originalBeanName(name));
}
RootBeanDefinition mbd = getMergedLocalBeanDefinition(beanName);
// Check decorated bean definition, if any: We assume it'll be easier
// to determine the decorated bean's type than the proxy's type.
BeanDefinitionHolder dbd = mbd.getDecoratedDefinition();
if (dbd != null && !BeanFactoryUtils.isFactoryDereference(name)) {
RootBeanDefinition tbd = getMergedBeanDefinition(dbd.getBeanName(), dbd.getBeanDefinition(), mbd);
Class<?> targetClass = predictBeanType(dbd.getBeanName(), tbd);
if (targetClass != null && !FactoryBean.class.isAssignableFrom(targetClass)) {
return targetClass;
}
}
Class<?> beanClass = predictBeanType(beanName, mbd);
// Check bean class whether we're dealing with a FactoryBean.
if (beanClass != null && FactoryBean.class.isAssignableFrom(beanClass)) {
if (!BeanFactoryUtils.isFactoryDereference(name)) {
// If it's a FactoryBean, we want to look at what it creates, not at the factory class.
return getTypeForFactoryBean(beanName, mbd);
}
else {
return beanClass;
}
}
else {
return (!BeanFactoryUtils.isFactoryDereference(name) ? beanClass : null);
}
}
}
//重写了，得到别名的方法。
@Override
public String[] getAliases(String name) {
String beanName = transformedBeanName(name);
List<String> aliases = new ArrayList<String>();
boolean factoryPrefix = name.startsWith(FACTORY_BEAN_PREFIX);
String fullBeanName = beanName;
if (factoryPrefix) {
fullBeanName = FACTORY_BEAN_PREFIX + beanName;
}
if (!fullBeanName.equals(name)) {
aliases.add(fullBeanName);
}
String[] retrievedAliases = super.getAliases(beanName);
for (String retrievedAlias : retrievedAliases) {
String alias = (factoryPrefix ? FACTORY_BEAN_PREFIX : "") + retrievedAlias;
if (!alias.equals(name)) {
aliases.add(alias);
}
}
if (!containsSingleton(beanName) && !containsBeanDefinition(beanName)) {
BeanFactory parentBeanFactory = getParentBeanFactory();
if (parentBeanFactory != null) {
aliases.addAll(Arrays.asList(parentBeanFactory.getAliases(fullBeanName)));
}
}
return StringUtils.toStringArray(aliases);
}
//---------------------------------------------------------------------
// Implementation of HierarchicalBeanFactory interface
//---------------------------------------------------------------------
//返回本Bean工厂的父Bean工厂
public BeanFactory getParentBeanFactory() {
return this.parentBeanFactory;
}
//是否在本容器中（就是说，并不是工厂bean生产出来的）
public boolean containsLocalBean(String name) {
String beanName = transformedBeanName(name); // 转换后的名字
//（是否为单例或有对应的Bean定义） 且（不是工厂Bean生产出来的 或 本身就是工厂bean）
return ((containsSingleton(beanName) || containsBeanDefinition(beanName)) &&
(!BeanFactoryUtils.isFactoryDereference(name) || isFactoryBean(beanName)));
}
//---------------------------------------------------------------------
// Implementation of ConfigurableBeanFactory interface
//---------------------------------------------------------------------
public void setParentBeanFactory(BeanFactory parentBeanFactory) {
if (this.parentBeanFactory != null && this.parentBeanFactory != parentBeanFactory) {
throw new IllegalStateException("Already associated with parent BeanFactory: " + this.parentBeanFactory);
}
this.parentBeanFactory = parentBeanFactory;
}
public void setBeanClassLoader(ClassLoader beanClassLoader) {
this.beanClassLoader = (beanClassLoader != null ? beanClassLoader : ClassUtils.getDefaultClassLoader());
}
public ClassLoader getBeanClassLoader() {
return this.beanClassLoader;
}
public void setTempClassLoader(ClassLoader tempClassLoader) {
this.tempClassLoader = tempClassLoader;
}
public ClassLoader getTempClassLoader() {
return this.tempClassLoader;
}
public void setCacheBeanMetadata(boolean cacheBeanMetadata) {
this.cacheBeanMetadata = cacheBeanMetadata;
}
public boolean isCacheBeanMetadata() {
return this.cacheBeanMetadata;
}
public void setBeanExpressionResolver(BeanExpressionResolver resolver) {
this.beanExpressionResolver = resolver;
}
public BeanExpressionResolver getBeanExpressionResolver() {
return this.beanExpressionResolver;
}
public void setConversionService(ConversionService conversionService) {
this.conversionService = conversionService;
}
public ConversionService getConversionService() {
return this.conversionService;
}
public void addPropertyEditorRegistrar(PropertyEditorRegistrar registrar) {
Assert.notNull(registrar, "PropertyEditorRegistrar must not be null");
this.propertyEditorRegistrars.add(registrar);
}
/**
* Return the set of PropertyEditorRegistrars.
*/
public Set<PropertyEditorRegistrar> getPropertyEditorRegistrars() {
return this.propertyEditorRegistrars;
}
public void registerCustomEditor(Class<?> requiredType, Class<? extends PropertyEditor> propertyEditorClass) {
Assert.notNull(requiredType, "Required type must not be null");
Assert.isAssignable(PropertyEditor.class, propertyEditorClass);
this.customEditors.put(requiredType, propertyEditorClass);
}
public void copyRegisteredEditorsTo(PropertyEditorRegistry registry) {
registerCustomEditors(registry);
}
/**
* Return the map of custom editors, with Classes as keys and PropertyEditor classes as values.
*/
public Map<Class<?>, Class<? extends PropertyEditor>> getCustomEditors() {
return this.customEditors;
}
public void setTypeConverter(TypeConverter typeConverter) {
this.typeConverter = typeConverter;
}
//得到通用的类型转换器
protected TypeConverter getCustomTypeConverter() {
return this.typeConverter;
}
//得到类型转换器
public TypeConverter getTypeConverter() {
TypeConverter customConverter = getCustomTypeConverter();
if (customConverter != null) {
return customConverter;
}
else {//若本容器未注册类型转换器，就创建一个简单的类型转换器
SimpleTypeConverter typeConverter = new SimpleTypeConverter();
typeConverter.setConversionService(getConversionService());
registerCustomEditors(typeConverter);
return typeConverter;
}
}
public void addEmbeddedValueResolver(StringValueResolver valueResolver) {
Assert.notNull(valueResolver, "StringValueResolver must not be null");
this.embeddedValueResolvers.add(valueResolver);
}
public String resolveEmbeddedValue(String value) {
String result = value;
for (StringValueResolver resolver : this.embeddedValueResolvers) {
if (result == null) {
return null;
}
result = resolver.resolveStringValue(result);
}
return result;
}
public void addBeanPostProcessor(BeanPostProcessor beanPostProcessor) {
Assert.notNull(beanPostProcessor, "BeanPostProcessor must not be null");
this.beanPostProcessors.remove(beanPostProcessor);
this.beanPostProcessors.add(beanPostProcessor);
if (beanPostProcessor instanceof InstantiationAwareBeanPostProcessor) {
this.hasInstantiationAwareBeanPostProcessors = true;
}
if (beanPostProcessor instanceof DestructionAwareBeanPostProcessor) {
this.hasDestructionAwareBeanPostProcessors = true;
}
}
public int getBeanPostProcessorCount() {
return this.beanPostProcessors.size();
}
/**
* Return the list of BeanPostProcessors that will get applied
* to beans created with this factory.
*/
public List<BeanPostProcessor> getBeanPostProcessors() {
return this.beanPostProcessors;
}
/**
* Return whether this factory holds a InstantiationAwareBeanPostProcessor
* that will get applied to singleton beans on shutdown.
* @see #addBeanPostProcessor
* @see org.springframework.beans.factory.config.InstantiationAwareBeanPostProcessor
*/
protected boolean hasInstantiationAwareBeanPostProcessors() {
return this.hasInstantiationAwareBeanPostProcessors;
}
/**
* Return whether this factory holds a DestructionAwareBeanPostProcessor
* that will get applied to singleton beans on shutdown.
* @see #addBeanPostProcessor
* @see org.springframework.beans.factory.config.DestructionAwareBeanPostProcessor
*/
protected boolean hasDestructionAwareBeanPostProcessors() {
return this.hasDestructionAwareBeanPostProcessors;
}
public void registerScope(String scopeName, Scope scope) {
Assert.notNull(scopeName, "Scope identifier must not be null");
Assert.notNull(scope, "Scope must not be null");
if (SCOPE_SINGLETON.equals(scopeName) || SCOPE_PROTOTYPE.equals(scopeName)) {
throw new IllegalArgumentException("Cannot replace existing scopes 'singleton' and 'prototype'");
}
this.scopes.put(scopeName, scope);
}
public String[] getRegisteredScopeNames() {
return StringUtils.toStringArray(this.scopes.keySet());
}
public Scope getRegisteredScope(String scopeName) {
Assert.notNull(scopeName, "Scope identifier must not be null");
return this.scopes.get(scopeName);
}
/**
* Set the security context provider for this bean factory. If a security manager
* is set, interaction with the user code will be executed using the privileged
* of the provided security context.
*/
public void setSecurityContextProvider(SecurityContextProvider securityProvider) {
this.securityContextProvider = securityProvider;
}
/**
* Delegate the creation of the access control context to the
* {@link #setSecurityContextProvider SecurityContextProvider}.
*/
@Override
public AccessControlContext getAccessControlContext() {
return (this.securityContextProvider != null ?
this.securityContextProvider.getAccessControlContext() :
AccessController.getContext());
}
public void copyConfigurationFrom(ConfigurableBeanFactory otherFactory) {
Assert.notNull(otherFactory, "BeanFactory must not be null");
setBeanClassLoader(otherFactory.getBeanClassLoader());
setCacheBeanMetadata(otherFactory.isCacheBeanMetadata());
setBeanExpressionResolver(otherFactory.getBeanExpressionResolver());
if (otherFactory instanceof AbstractBeanFactory) {
AbstractBeanFactory otherAbstractFactory = (AbstractBeanFactory) otherFactory;
this.customEditors.putAll(otherAbstractFactory.customEditors);
this.propertyEditorRegistrars.addAll(otherAbstractFactory.propertyEditorRegistrars);
this.beanPostProcessors.addAll(otherAbstractFactory.beanPostProcessors);
this.hasInstantiationAwareBeanPostProcessors = this.hasInstantiationAwareBeanPostProcessors ||
otherAbstractFactory.hasInstantiationAwareBeanPostProcessors;
this.hasDestructionAwareBeanPostProcessors = this.hasDestructionAwareBeanPostProcessors ||
otherAbstractFactory.hasDestructionAwareBeanPostProcessors;
this.scopes.putAll(otherAbstractFactory.scopes);
this.securityContextProvider = otherAbstractFactory.securityContextProvider;
}
else {
setTypeConverter(otherFactory.getTypeConverter());
}
}
//返回合并后的bean定义（父Bean定义和子Bean定义合并）
public BeanDefinition getMergedBeanDefinition(String name) throws BeansException {
String beanName = transformedBeanName(name);
// Efficiently check whether bean definition exists in this factory.
//若Bean定义不存在，且本容器父工厂为ConfigurableBeanFactory的实例，让父工厂来调用这个方法
if (!containsBeanDefinition(beanName) && getParentBeanFactory() instanceof ConfigurableBeanFactory) {
return ((ConfigurableBeanFactory) getParentBeanFactory()).getMergedBeanDefinition(beanName);
}
//否则直接从本地合并后的Bean定义中取
return getMergedLocalBeanDefinition(beanName);
}
public boolean isFactoryBean(String name) throws NoSuchBeanDefinitionException {
String beanName = transformedBeanName(name);
Object beanInstance = getSingleton(beanName, false);
if (beanInstance != null) {
return (beanInstance instanceof FactoryBean);
}
else if (containsSingleton(beanName)) {
// null instance registered
return false;
}
// No singleton instance found -> check bean definition.
if (!containsBeanDefinition(beanName) && getParentBeanFactory() instanceof ConfigurableBeanFactory) {
// No bean definition found in this factory -> delegate to parent.
return ((ConfigurableBeanFactory) getParentBeanFactory()).isFactoryBean(name);
}
return isFactoryBean(beanName, getMergedLocalBeanDefinition(beanName));
}
@Override
public boolean isActuallyInCreation(String beanName) {
return isSingletonCurrentlyInCreation(beanName) || isPrototypeCurrentlyInCreation(beanName);
}
// 判断指定的原型是否正在被创建
protected boolean isPrototypeCurrentlyInCreation(String beanName) {
Object curVal = this.prototypesCurrentlyInCreation.get();
return (curVal != null &&
(curVal.equals(beanName) || (curVal instanceof Set && ((Set<?>) curVal).contains(beanName))));
}
//原型创建前回调，需要子类重写
@SuppressWarnings("unchecked")
protected void beforePrototypeCreation(String beanName) {
Object curVal = this.prototypesCurrentlyInCreation.get();
if (curVal == null) {//原型创建状态与当前线程绑定
this.prototypesCurrentlyInCreation.set(beanName);
}
else if (curVal instanceof String) {
Set<String> beanNameSet = new HashSet<String>(2);
beanNameSet.add((String) curVal);
beanNameSet.add(beanName);
this.prototypesCurrentlyInCreation.set(beanNameSet);
}
//这里多余了。。。
else {
Set<String> beanNameSet = (Set<String>) curVal;
beanNameSet.add(beanName);
}
}
//创建原型后，从当前线程解除绑定
@SuppressWarnings("unchecked")
protected void afterPrototypeCreation(String beanName) {
Object curVal = this.prototypesCurrentlyInCreation.get();
if (curVal instanceof String) {
this.prototypesCurrentlyInCreation.remove();
}
else if (curVal instanceof Set) {
Set<String> beanNameSet = (Set<String>) curVal;
beanNameSet.remove(beanName);
if (beanNameSet.isEmpty()) {
this.prototypesCurrentlyInCreation.remove();
}
}
}
public void destroyBean(String beanName, Object beanInstance) {
destroyBean(beanName, beanInstance, getMergedLocalBeanDefinition(beanName));
}
/**
* Destroy the given bean instance (usually a prototype instance
* obtained from this factory) according to the given bean definition.
* @param beanName the name of the bean definition
* @param beanInstance the bean instance to destroy
* @param mbd the merged bean definition
*/
protected void destroyBean(String beanName, Object beanInstance, RootBeanDefinition mbd) {
new DisposableBeanAdapter(beanInstance, beanName, mbd, getBeanPostProcessors(), getAccessControlContext()).destroy();
}
public void destroyScopedBean(String beanName) {
RootBeanDefinition mbd = getMergedLocalBeanDefinition(beanName);
if (mbd.isSingleton() || mbd.isPrototype()) {
throw new IllegalArgumentException(
"Bean name '" + beanName + "' does not correspond to an object in a mutable scope");
}
String scopeName = mbd.getScope();
Scope scope = this.scopes.get(scopeName);
if (scope == null) {
throw new IllegalStateException("No Scope SPI registered for scope '" + scopeName + "'");
}
Object bean = scope.remove(beanName);
if (bean != null) {
destroyBean(beanName, bean, mbd);
}
}
//---------------------------------------------------------------------
// Implementation methods
//---------------------------------------------------------------------
//变换后的Bean名称（先去掉BeanFactory前缀，然后在aliasMap中取标准名）
protected String transformedBeanName(String name) {
return canonicalName(BeanFactoryUtils.transformedBeanName(name));
}
//返回原始的Bean名
protected String originalBeanName(String name) {
String beanName = transformedBeanName(name);
if (name.startsWith(FACTORY_BEAN_PREFIX)) {
beanName = FACTORY_BEAN_PREFIX + beanName;
}
return beanName;
}
/**
* Initialize the given BeanWrapper with the custom editors registered
* with this factory. To be called for BeanWrappers that will create
* and populate bean instances.
* <p>The default implementation delegates to {@link #registerCustomEditors}.
* Can be overridden in subclasses.
* @param bw the BeanWrapper to initialize
*/
protected void initBeanWrapper(BeanWrapper bw) {
bw.setConversionService(getConversionService());
registerCustomEditors(bw);
}
/**
* Initialize the given PropertyEditorRegistry with the custom editors
* that have been registered with this BeanFactory.
* <p>To be called for BeanWrappers that will create and populate bean
* instances, and for SimpleTypeConverter used for constructor argument
* and factory method type conversion.
* @param registry the PropertyEditorRegistry to initialize
*/
protected void registerCustomEditors(PropertyEditorRegistry registry) {
PropertyEditorRegistrySupport registrySupport =
(registry instanceof PropertyEditorRegistrySupport ? (PropertyEditorRegistrySupport) registry : null);
if (registrySupport != null) {
registrySupport.useConfigValueEditors();
}
if (!this.propertyEditorRegistrars.isEmpty()) {
for (PropertyEditorRegistrar registrar : this.propertyEditorRegistrars) {
try {
registrar.registerCustomEditors(registry);
}
catch (BeanCreationException ex) {
Throwable rootCause = ex.getMostSpecificCause();
if (rootCause instanceof BeanCurrentlyInCreationException) {
BeanCreationException bce = (BeanCreationException) rootCause;
if (isCurrentlyInCreation(bce.getBeanName())) {
if (logger.isDebugEnabled()) {
logger.debug("PropertyEditorRegistrar [" + registrar.getClass().getName() +
"] failed because it tried to obtain currently created bean '" +
ex.getBeanName() + "': " + ex.getMessage());
}
onSuppressedException(ex);
continue;
}
}
throw ex;
}
}
}
if (!this.customEditors.isEmpty()) {
for (Map.Entry<Class<?>, Class<? extends PropertyEditor>> entry : this.customEditors.entrySet()) {
Class<?> requiredType = entry.getKey();
Class<? extends PropertyEditor> editorClass = entry.getValue();
registry.registerCustomEditor(requiredType, BeanUtils.instantiateClass(editorClass));
}
}
}
//返回一个合并后的根Bean定义（父Bean定义和子Bean定义合并）（从当前容器取）
protected RootBeanDefinition getMergedLocalBeanDefinition(String beanName) throws BeansException {
// Quick check on the concurrent map first, with minimal locking.
RootBeanDefinition mbd = this.mergedBeanDefinitions.get(beanName);//首先直接从合并根定义集合中取
if (mbd != null) {
return mbd;
}
//根据bean名和其对应的Bean定义，取其根Bean根定义
return getMergedBeanDefinition(beanName, getBeanDefinition(beanName));
}
//根据Bean名和Bean定义取其Bean根定义
protected RootBeanDefinition getMergedBeanDefinition(String beanName, BeanDefinition bd)
throws BeanDefinitionStoreException {
return getMergedBeanDefinition(beanName, bd, null);//调用重载方法
}
//根据Bean名称返回根定义（若给定的Bean定义为子Bean定义，那么合并它的父Bean定义）
protected RootBeanDefinition getMergedBeanDefinition(
String beanName, BeanDefinition bd, BeanDefinition containingBd)
throws BeanDefinitionStoreException {
synchronized (this.mergedBeanDefinitions) {
RootBeanDefinition mbd = null;
//若给定的Bean定义并没有包含子Bean定义，那么直接根据Bean名取根定义
if (containingBd == null) {
mbd = this.mergedBeanDefinitions.get(beanName);
}
if (mbd == null) {//若取不到
if (bd.getParentName() == null) {//若Bean定义没有父类，就很简单了
if (bd instanceof RootBeanDefinition) {//若Bean定义是RootBeanDefinition的实例，克隆、强转后返回
mbd = ((RootBeanDefinition) bd).cloneBeanDefinition();
}
else {//否则，根据Bean定义，来构造一个根Bean定义
mbd = new RootBeanDefinition(bd);
}
}
else {//若Bean定义有父类
// Child bean definition: needs to be merged with parent.
BeanDefinition pbd;
try {
String parentBeanName = transformedBeanName(bd.getParentName());//取其父Bean定义的名字
if (!beanName.equals(parentBeanName)) {//若Bean名字并不是bd的父Bean的名字
pbd = getMergedBeanDefinition(parentBeanName);//根据父Bean定义名称来返回合并后的bean定义
}
else {//如果beanName对应的Bean就是bd的父Bean
if (getParentBeanFactory() instanceof ConfigurableBeanFactory) {//若父Bean工厂为ConfigurableBeanFactory的实例
// 那么强转成ConfigurableBeanFactory后再调用合并方法
pbd = ((ConfigurableBeanFactory) getParentBeanFactory()).getMergedBeanDefinition(parentBeanName);
}
else {//若父Bean工厂不是ConfigurableBeanFactory的实例，就抛出异常
throw new NoSuchBeanDefinitionException(bd.getParentName(),
"Parent name '" + bd.getParentName() + "' is equal to bean name '" + beanName +
"': cannot be resolved without an AbstractBeanFactory parent");
}
}
}
catch (NoSuchBeanDefinitionException ex) {
throw new BeanDefinitionStoreException(bd.getResourceDescription(), beanName,
"Could not resolve parent bean definition '" + bd.getParentName() + "'", ex);
}
// 深度复制
mbd = new RootBeanDefinition(pbd);//根据Bean定义生成一个根Bean定义
mbd.overrideFrom(bd);//将Bean定义的属性复制进自己的定义（根Bean定义）中
}
if (!StringUtils.hasLength(mbd.getScope())) {//如果根Bean定义未设置范围
mbd.setScope(RootBeanDefinition.SCOPE_SINGLETON);//那么设置其范围为单例
}
// 若本根Bean定义包含Bean定义、本根Bean定义为单例且包含的Bean定义并不是单例
if (containingBd != null && !containingBd.isSingleton() && mbd.isSingleton()) {
mbd.setScope(containingBd.getScope());// 那么将本根Bean定义的范围设置为包含的Bean定义的范围
}
//若本根Bean定义不包含Bean定义，且是缓存Bean元数据（重写前均为true）且Bean定义是否有资格缓存（默认实现是，这个Bean已经创建便有资格）
if (containingBd == null && isCacheBeanMetadata() && isBeanEligibleForMetadataCaching(beanName)) {
this.mergedBeanDefinitions.put(beanName, mbd);//放进mergedBeanDefinitions中
}
}
return mbd;
}
}
//检查Bean定义，抛出异常
protected void checkMergedBeanDefinition(RootBeanDefinition mbd, String beanName, Object[] args)
throws BeanDefinitionStoreException {
if (mbd.isAbstract()) {
throw new BeanIsAbstractException(beanName);
}
if (args != null && !mbd.isPrototype()) {
throw new BeanDefinitionStoreException(
"Can only specify arguments for the getBean method when referring to a prototype bean definition");
}
}
/**
* Remove the merged bean definition for the specified bean,
* recreating it on next access.
* @param beanName the bean name to clear the merged definition for
*/
protected void clearMergedBeanDefinition(String beanName) {
this.mergedBeanDefinitions.remove(beanName);
}
//解析类型，处理异常
protected Class<?> resolveBeanClass(final RootBeanDefinition mbd, String beanName, final Class<?>... typesToMatch)
throws CannotLoadBeanClassException {
try {
if (mbd.hasBeanClass()) {
return mbd.getBeanClass();
}
if (System.getSecurityManager() != null) {
return AccessController.doPrivileged(new PrivilegedExceptionAction<Class<?>>() {
public Class<?> run() throws Exception {
return doResolveBeanClass(mbd, typesToMatch);
}
}, getAccessControlContext());
}
else {
return doResolveBeanClass(mbd, typesToMatch);
}
}
catch (PrivilegedActionException pae) {
ClassNotFoundException ex = (ClassNotFoundException) pae.getException();
throw new CannotLoadBeanClassException(mbd.getResourceDescription(), beanName, mbd.getBeanClassName(), ex);
}
catch (ClassNotFoundException ex) {
throw new CannotLoadBeanClassException(mbd.getResourceDescription(), beanName, mbd.getBeanClassName(), ex);
}
catch (LinkageError err) {
throw new CannotLoadBeanClassException(mbd.getResourceDescription(), beanName, mbd.getBeanClassName(), err);
}
}
// 真正的解析类型
private Class<?> doResolveBeanClass(RootBeanDefinition mbd, Class<?>... typesToMatch) throws ClassNotFoundException {
if (!ObjectUtils.isEmpty(typesToMatch)) {
ClassLoader tempClassLoader = getTempClassLoader();//找到临时的类加载器
if (tempClassLoader != null) {
if (tempClassLoader instanceof DecoratingClassLoader) {//若为装饰类加载器
DecoratingClassLoader dcl = (DecoratingClassLoader) tempClassLoader;
for (Class<?> typeToMatch : typesToMatch) {
dcl.excludeClass(typeToMatch.getName());
}
}
String className = mbd.getBeanClassName();
return (className != null ? ClassUtils.forName(className, tempClassLoader) : null);
}
}
return mbd.resolveBeanClass(getBeanClassLoader());
}
/**
* Evaluate the given String as contained in a bean definition,
* potentially resolving it as an expression.
* @param value the value to check
* @param beanDefinition the bean definition that the value comes from
* @return the resolved value
* @see #setBeanExpressionResolver
*/
protected Object evaluateBeanDefinitionString(String value, BeanDefinition beanDefinition) {
if (this.beanExpressionResolver == null) {
return value;
}
Scope scope = (beanDefinition != null ? getRegisteredScope(beanDefinition.getScope()) : null);
return this.beanExpressionResolver.evaluate(value, new BeanExpressionContext(this, scope));
}
//预测类型
protected Class<?> predictBeanType(String beanName, RootBeanDefinition mbd, Class<?>... typesToMatch) {
//若根Bena定义的工厂方法名存在，说明它是工厂Bean创建的，无法预测类型？
if (mbd.getFactoryMethodName() != null) {
return null;
}
//否则，解析Bean的Class
return resolveBeanClass(mbd, beanName, typesToMatch);
}
/**
* Check whether the given bean is defined as a {@link FactoryBean}.
* @param beanName the name of the bean
* @param mbd the corresponding bean definition
*/
protected boolean isFactoryBean(String beanName, RootBeanDefinition mbd) {
Class<?> beanType = predictBeanType(beanName, mbd, FactoryBean.class);
return (beanType != null && FactoryBean.class.isAssignableFrom(beanType));
}
//返回工厂Bean的类型
protected Class<?> getTypeForFactoryBean(String beanName, RootBeanDefinition mbd) {
if (!mbd.isSingleton()) {
return null;
}
try {
FactoryBean<?> factoryBean = doGetBean(FACTORY_BEAN_PREFIX + beanName, FactoryBean.class, null, true);
return getTypeForFactoryBean(factoryBean);
}
catch (BeanCreationException ex) {
// Can only happen when getting a FactoryBean.
if (logger.isDebugEnabled()) {
logger.debug("Ignoring bean creation exception on FactoryBean type check: " + ex);
}
onSuppressedException(ex);
return null;
}
}
//标记这个Bean已经被创建
protected void markBeanAsCreated(String beanName) {
this.alreadyCreated.put(beanName, Boolean.TRUE);
}
/**
* Determine whether the specified bean is eligible for having
* its bean definition metadata cached.
* @param beanName the name of the bean
* @return {@code true} if the bean's metadata may be cached
* at this point already
*/
//若本根Bean定义包含Bean元定义作为缓存，这个方法应被之类覆盖，这里仅判断Bean是否已经被创建
protected boolean isBeanEligibleForMetadataCaching(String beanName) {
return this.alreadyCreated.containsKey(beanName);
}
/**
* Remove the singleton instance (if any) for the given bean name,
* but only if it hasn't been used for other purposes than type checking.
* @param beanName the name of the bean
* @return {@code true} if actually removed, {@code false} otherwise
*/
protected boolean removeSingletonIfCreatedForTypeCheckOnly(String beanName) {
if (!this.alreadyCreated.containsKey(beanName)) {
removeSingleton(beanName);
return true;
}
else {
return false;
}
}
//根据给定的实例是否为工厂Bean，返回它自己或工厂Bean创建的实例
protected Object getObjectForBeanInstance(
Object beanInstance, String name, String beanName, RootBeanDefinition mbd) {
//如果这个Bean是工厂Bean创建的 且 这个Bean实例并不是FactoryBean实例，抛异常
if (BeanFactoryUtils.isFactoryDereference(name) && !(beanInstance instanceof FactoryBean)) {
throw new BeanIsNotAFactoryException(transformedBeanName(name), beanInstance.getClass());
}
//如果这个Bean实例并不是FactoryBean实例 或 这个Bean是工厂Bean创建的，直接返回
if (!(beanInstance instanceof FactoryBean) || BeanFactoryUtils.isFactoryDereference(name)) {
return beanInstance;
}
//——————————以下都是 这个Bean实例是FactoryBean实例的情况
Object object = null;
if (mbd == null) {//若根Bean定义为空，取这个BeanFactory所生产的实例
object = getCachedObjectForFactoryBean(beanName);
}
if (object == null) {//若取不到，那么手动取
FactoryBean<?> factory = (FactoryBean<?>) beanInstance;//把这个实例转化成一个FactoryBean
// Caches object obtained from FactoryBean if it is a singleton.
if (mbd == null && containsBeanDefinition(beanName)) {//若根Bean定义为空，但是容器内有Bean定义
mbd = getMergedLocalBeanDefinition(beanName);//返回合并后的Bean定义
}
boolean synthetic = (mbd != null && mbd.isSynthetic());//标记这个Bean定义是合并的
object = getObjectFromFactoryBean(factory, beanName, !synthetic);//从工厂Bean中取
}
return object;
}
//判断给定的Bean是否被使用过
public boolean isBeanNameInUse(String beanName) {
//若是别名 或 并非工厂bean生产出来的 或 被其他某个bean所依赖，那么判断其被使用过
return isAlias(beanName) || containsLocalBean(beanName) || hasDependentBean(beanName);
}
/**
* Determine whether the given bean requires destruction on shutdown.
* <p>The default implementation checks the DisposableBean interface as well as
* a specified destroy method and registered DestructionAwareBeanPostProcessors.
* @param bean the bean instance to check
* @param mbd the corresponding bean definition
* @see org.springframework.beans.factory.DisposableBean
* @see AbstractBeanDefinition#getDestroyMethodName()
* @see org.springframework.beans.factory.config.DestructionAwareBeanPostProcessor
*/
protected boolean requiresDestruction(Object bean, RootBeanDefinition mbd) {
return (bean != null &&
(DisposableBeanAdapter.hasDestroyMethod(bean, mbd) || hasDestructionAwareBeanPostProcessors()));
}
/**
* Add the given bean to the list of disposable beans in this factory,
* registering its DisposableBean interface and/or the given destroy method
* to be called on factory shutdown (if applicable). Only applies to singletons.
* @param beanName the name of the bean
* @param bean the bean instance
* @param mbd the bean definition for the bean
* @see RootBeanDefinition#isSingleton
* @see RootBeanDefinition#getDependsOn
* @see #registerDisposableBean
* @see #registerDependentBean
*/
protected void registerDisposableBeanIfNecessary(String beanName, Object bean, RootBeanDefinition mbd) {
AccessControlContext acc = (System.getSecurityManager() != null ? getAccessControlContext() : null);
if (!mbd.isPrototype() && requiresDestruction(bean, mbd)) {
if (mbd.isSingleton()) {
// Register a DisposableBean implementation that performs all destruction
// work for the given bean: DestructionAwareBeanPostProcessors,
// DisposableBean interface, custom destroy method.
registerDisposableBean(beanName,
new DisposableBeanAdapter(bean, beanName, mbd, getBeanPostProcessors(), acc));
}
else {
// A bean with a custom scope...
Scope scope = this.scopes.get(mbd.getScope());
if (scope == null) {
throw new IllegalStateException("No Scope registered for scope '" + mbd.getScope() + "'");
}
scope.registerDestructionCallback(beanName,
new DisposableBeanAdapter(bean, beanName, mbd, getBeanPostProcessors(), acc));
}
}
}
//---------------------------------------------------------------------
// Abstract methods to be implemented by subclasses
//---------------------------------------------------------------------
//标记是否包含Bean定义的方法
protected abstract boolean containsBeanDefinition(String beanName);
//根据Bean名返回其BeanDefinition
protected abstract BeanDefinition getBeanDefinition(String beanName) throws BeansException;
//根据指定的bean定义和bean名、参数，创建对象
protected abstract Object createBean(String beanName, RootBeanDefinition mbd, Object[] args)
throws BeanCreationException;
}
总结：方法太多了，一个个介绍很浪费时间，不具体介绍。大体介绍一下吧。这个AbstractBeanFactory继承了支持工厂Bean注册的FactoryBeanRegistrySupport，并且实现了BeanFactory重要的第三级接口——ConfigurableBeanFactory。需要具体了解这个接口，可以去看我之前的接口分析——Spring源码分析——BeanFactory体系之接口详细分析 。ConfigurableBeanFactory是一个非常复杂的接口，继承了HierarchicalBeanFactory和SingletonBeanRegistry，主要实现了工厂创建、注册Bean、单例类注册等各种功能。
AbstractBeanFactory实现了ConfigurableBeanFactory接口的绝大多数方法，实现了Bean工厂的许多重要功能，如BeanDefinition、RootBeanDefinition、原型、单例相关的各种操作。
下面列出一些主要方法实现，其他的方法说明，可具体参照上文我贴出的大部分注释过的源码。
（1）、从容器中获取bean的方法——doGetBean：
@SuppressWarnings("unchecked")
protected <T> T doGetBean(
final String name, final Class<T> requiredType, final Object[] args, boolean typeCheckOnly)
throws BeansException {
final String beanName = transformedBeanName(name);//在aliasMap中取得的标准名
Object bean;
// Eagerly check singleton cache for manually registered singletons.
Object sharedInstance = getSingleton(beanName);//首先在单例集合中取
if (sharedInstance != null && args == null) {//如果取得到，没有指定参数
if (logger.isDebugEnabled()) {//若Log允许调试
if (isSingletonCurrentlyInCreation(beanName)) {//若正准备创建，输出日志
logger.debug("Returning eagerly cached instance of singleton bean '" + beanName +
"' that is not fully initialized yet - a consequence of a circular reference");
}
else {
logger.debug("Returning cached instance of singleton bean '" + beanName + "'");
}
}
////根据给定的实例是否为工厂Bean，返回它自己或工厂Bean创建的实例
bean = getObjectForBeanInstance(sharedInstance, name, beanName, null);
}
else {
if (isPrototypeCurrentlyInCreation(beanName)) {//如果正在被创建，就抛出异常
throw new BeanCurrentlyInCreationException(beanName);
}
BeanFactory parentBeanFactory = getParentBeanFactory();//取本容器的父容器
if (parentBeanFactory != null && !containsBeanDefinition(beanName)) {//若存在父容器，且本容器不存在对应的Bean定义
String nameToLookup = originalBeanName(name);//取原始的Bean名
if (args != null) {//若参数列表存在
// 那么用父容器根据原始Bean名和参数列表返回
return (T) parentBeanFactory.getBean(nameToLookup, args);
}
else {
// 参数列表不要求，那就直接根据原始名称和要求的类型返回
return parentBeanFactory.getBean(nameToLookup, requiredType);
}
}
//如果不需要类型检查，标记其已经被创建
if (!typeCheckOnly) {
markBeanAsCreated(beanName);
}
//根据beanName取其根Bean定义
final RootBeanDefinition mbd = getMergedLocalBeanDefinition(beanName);
checkMergedBeanDefinition(mbd, beanName, args);
String[] dependsOn = mbd.getDependsOn();//得到这个根定义的所有依赖
if (dependsOn != null) {
for (String dependsOnBean : dependsOn) {
getBean(dependsOnBean);//注册这个Bean
//注册一个Bean和依赖于它的Bean（后参数依赖前参数）
registerDependentBean(dependsOnBean, beanName);
}
}
// 如果Bean定义是单例，就在返回单例
if (mbd.isSingleton()) {
sharedInstance = getSingleton(beanName, new ObjectFactory<Object>() {
public Object getObject() throws BeansException {
try {
return createBean(beanName, mbd, args);
}
catch (BeansException ex) {
destroySingleton(beanName);
throw ex;
}
}
});
//根据给定的实例是否为工厂Bean，返回它自己或工厂Bean创建的实例
bean = getObjectForBeanInstance(sharedInstance, name, beanName, mbd);
}
//如果是原型
else if (mbd.isPrototype()) {
// It's a prototype -> create a new instance.
Object prototypeInstance = null;
try {
beforePrototypeCreation(beanName);//原型创建前，与当前线程绑定
prototypeInstance = createBean(beanName, mbd, args);
}
finally {
afterPrototypeCreation(beanName);//原型创建后，与当前线程解除绑定
}
bean = getObjectForBeanInstance(prototypeInstance, name, beanName, mbd);
}
else {//既不是单例又不是原型的情况
String scopeName = mbd.getScope();
final Scope scope = this.scopes.get(scopeName);//得到范围
if (scope == null) {
throw new IllegalStateException("No Scope registered for scope '" + scopeName + "'");
}
try {//根据范围创建实例
Object scopedInstance = scope.get(beanName, new ObjectFactory<Object>() {
public Object getObject() throws BeansException {
beforePrototypeCreation(beanName);
try {
return createBean(beanName, mbd, args);//原型创建前，与当前线程绑定
}
finally {
////原型创建后，与当前线程解除绑定
afterPrototypeCreation(beanName);
}
}
});
//根据给定的实例是否为工厂Bean，返回它自己或工厂Bean创建的实例
bean = getObjectForBeanInstance(scopedInstance, name, beanName, mbd);
}
catch (IllegalStateException ex) {
throw new BeanCreationException(beanName,
"Scope '" + scopeName + "' is not active for the current thread; " +
"consider defining a scoped proxy for this bean if you intend to refer to it from a singleton",
ex);
}
}
}
//判断要求的类型是否和Bean实例的类型正在匹配
if (requiredType != null && bean != null && !requiredType.isAssignableFrom(bean.getClass())) {
try {
return getTypeConverter().convertIfNecessary(bean, requiredType);//转换类型，不抛出异常就说明类型匹配
}
catch (TypeMismatchException ex) {
if (logger.isDebugEnabled()) {
logger.debug("Failed to convert bean '" + name + "' to required type [" +
ClassUtils.getQualifiedName(requiredType) + "]", ex);
}
throw new BeanNotOfRequiredTypeException(name, requiredType, bean.getClass());
}
}
return (T) bean;
}
下面对这个方法进行简要的解释：
<1>、这个方法形参为final String name, final Class<T> requiredType, final Object[] args, boolean typeCheckOnly，分别表示Bean的名称、要求返回的Bean的类型、取Bean时提供的参数数组 以及 是否需要类型检查。哦
<2>、final String beanName = transformedBeanName(name); 这个方法是从aliasMap中取得对应的标准名。方法实现是，首先去掉name的 FACTORY_BEAN_PREFIX 前缀（如果是工厂Bean本身，那么Bean名有这个前缀），然后调用SimpleAliasRegistry的canonicalName方法。上篇博客已经介绍过SimpleAliasRegistry了，这里贴一下这个方法的源码：
/*
* 根据name这个Key，在aliasMap中不断循环的取对应的value，如果取得到，就继续根据这个value取值，不断循环继续。
* 直到取不到，就把这个在aliasMap中无对应值的key返回。这个动作，叫规范名
*/
public String canonicalName(String name) {
String canonicalName = name; //规范名
// Handle aliasing...
String resolvedName;//已解析名
do {
resolvedName = this.aliasMap.get(canonicalName);//aliasMap中规范名对应的值赋值给已解析名
if (resolvedName != null) {//如果已解析名存在（即规范名在aliasMap中有对应的值）
canonicalName = resolvedName; // 这个已解析名赋值给标准名
}
} while (resolvedName != null);//不断循环，直到已解析名不存在
return canonicalName;
}
<3>、首先根据标准名beanName，在单例缓存中取对应的Bean：Object sharedInstance = getSingleton(beanName);
<4>、如果取得到，且args为空，根据给定的实例是否为工厂Bean，返回它自己或工厂Bean创建的实例：bean = getObjectForBeanInstance(sharedInstance, name, beanName, null);然后结束整个方法。这个方法源码如下：
//根据给定的实例是否为工厂Bean，返回它自己或工厂Bean创建的实例
protected Object getObjectForBeanInstance(
Object beanInstance, String name, String beanName, RootBeanDefinition mbd) { //如果这个Bean是工厂Bean创建的 且 这个Bean实例并不是FactoryBean实例，抛异常
if (BeanFactoryUtils.isFactoryDereference(name) && !(beanInstance instanceof FactoryBean)) {
throw new BeanIsNotAFactoryException(transformedBeanName(name), beanInstance.getClass());
} //如果这个Bean实例并不是FactoryBean实例 或 这个Bean是工厂Bean创建的，直接返回
if (!(beanInstance instanceof FactoryBean) || BeanFactoryUtils.isFactoryDereference(name)) {
return beanInstance;
} //——————————以下都是 这个Bean实例是FactoryBean实例的情况
Object object = null;
if (mbd == null) {//若根Bean定义为空，取这个BeanFactory所生产的实例
object = getCachedObjectForFactoryBean(beanName);
}
if (object == null) {//若取不到，那么手动取
FactoryBean<?> factory = (FactoryBean<?>) beanInstance;//把这个实例转化成一个FactoryBean
// Caches object obtained from FactoryBean if it is a singleton.
if (mbd == null && containsBeanDefinition(beanName)) {//若根Bean定义为空，但是容器内有Bean定义
mbd = getMergedLocalBeanDefinition(beanName);//返回合并后的Bean定义
}
boolean synthetic = (mbd != null && mbd.isSynthetic());//标记这个Bean定义是合并的
object = getObjectFromFactoryBean(factory, beanName, !synthetic);//从工厂Bean中取
}
return object;
<5>、如果取不到、或 args 不为空（下面都是基于这个条件）：
（如果对应的Bean正在被创建，就抛出异常）首先用父容器（如果本容器有的话）根据给出的形参取对应的Bean。
<6>、此时，判断，如果不需要类型检查，标记其已经被创建。
<7>、根据beanName取本地合并后的RootBeanDefinition（这个方法getMergedLocalBeanDefinition涉及到多层BeanDefinition相关的调用），然后检查一下。然后根据这个RootBeanDefinition，注册这个Bean和它的所有依赖。
<8>、如果这个RootBeanDefinition是单例，先根据beanName从单例缓存中取，取不到就创建一个匿名内部Bean工厂，创建一个单例，直接结束方法。
<9>、如果这个RootBeanDefinition是原型，就直接创建一个Bean返回，并在创建前把beanName与当前线程绑定，创建后解绑。
<10>、如果这个RootBeanDefinition既不是单例，又不是原型，那么根据这个RootBeanDefinition定义的范围Scope，直接创建一个scopedInstance。
<11>、若这个scopedInstance为工厂Bean，就得到它创建的实例，否则得到它自身。
<12>、对<9>或<11>中最后产生的Bean就进行一次检查，要求这个产生的Bean的类型是否和Bean实例的类型匹配，不匹配就抛出异常。
以上就是这个doGetBean方法了。其他的方法分析可参照上文的源码。
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