依赖配置中心实现注有@ConfigurationProperties的bean相关属性刷新

配置中心是什么

　　配置中心，通过key=value的形式存储环境变量。配置中心的属性做了修改，项目中可以通过配置中心的依赖（sdk）立即感知到。需要做的就是如何在属性发生变化时，改变带有@ConfigurationProperties的bean的相关属性。

配置中心原理

　　在读配置中心源码的时候发现，里面维护了一个Environment，以及ZookeeperPropertySource。当配置中心属性发生变化的时候，清空ZookeeperPropertySource，并放入最新的属性值。

　　

public class ZookeeperPropertySource extends EnumerablePropertySource<Properties>

　　

　　ZookeeperPropertySource重写了equals和hahscode方法，根据这两个方法可以判定配置中心是否修改了属性。

　　 

动态刷新bean属性原理

实现原理图

　　

动态刷新bean父类

public abstract class BaseConfigCenterBean implements InitializingBean {

    private static Logger LOGGER = LoggerFactory.getLogger(BaseConfigCenterBean.class);

    //配置中心是否生效
    protected boolean cfgCenterEffect = false;

    public boolean isCfgCenterEffect() {
        this.checkCfgCenterEffect();
        return cfgCenterEffect;
    }

    private void checkCfgCenterEffect() {
        boolean tmpCfgCenterEffect = !Objects.isNull(ConfigHelper.getEnvironment());
        if (tmpCfgCenterEffect) {// NOSONAR
            String value = (String) ConfigHelper.getZookeeperPropertySource().getProperty("cfg.center.effect");
            if (StringUtils.isBlank(value)) {
                tmpCfgCenterEffect = false;
            } else {
                tmpCfgCenterEffect = Boolean.valueOf(value);
            }
        }

        cfgCenterEffect = tmpCfgCenterEffect;

        if (cfgCenterEffect) {
            String prefix = this.getConfigPrefix();
            cfgCenterEffect = Arrays.stream(ConfigHelper.getZookeeperPropertySource().getPropertyNames())
                    .filter(keyName -> keyName.indexOf(prefix) == 0)
                    .count() > 0;
            if (!cfgCenterEffect) {
                LOGGER.info(String.format("配置中心没有发现模块=%s, prefix=%s的配置，将使用本地配置...", this.getModuleName(), prefix));
            }
        }
    }

    /**
     * 绑定自身目标
     **/
    protected void doBind() {
        Class<? extends BaseConfigCenterBean> clazz = this.getClass();
        if (AopUtils.isCglibProxy(this)) {
            clazz = (Class<? extends BaseConfigCenterBean>) AopUtils.getTargetClass(this);
        }
        BaseConfigCenterBean target = binding(isCfgCenterEffect(), clazz, this.getDefaultResourcePath());
        this.copyProperties(target);
    }

    private void copyProperties(BaseConfigCenterBean target) {
        ReflectionUtils.doWithFields(this.getClass(), field -> {
            field.setAccessible(true);
            field.set(this, field.get(target));
        }, field -> AnnotatedElementUtils.isAnnotated(field, ConfigField.class));
    }

    /**
     * 绑定其他目标
     *
     * @param clazz 目标类
     **/
    protected <T> T doBind(Class<T> clazz) {
        T target = binding(isCfgCenterEffect(), clazz, this.getDefaultResourcePath());
        if (target instanceof InitializingBean) {
            try {
                ((InitializingBean) target).afterPropertiesSet();
            } catch (Exception e) {
                LOGGER.error(String.format("属性初始化失败[afterPropertiesSet]， class=%s", ClassUtils.getSimpleName(clazz), e));
            }
        }
        return target;
    }

    private <T> T binding(boolean cfgCenterEffect, Class<T> clazz, String defaultResourcePath) {
        Optional<PropertySource> propertySource = Optional.empty();

        if (cfgCenterEffect) {
            propertySource = Optional.ofNullable(ConfigHelper.getZookeeperPropertySource());
        } else {
            Optional<ResourcePropertySource> resourcePropertySource = ResourceUtils.getResourcePropertySource(defaultResourcePath);
            if (resourcePropertySource.isPresent()) {
                propertySource = Optional.ofNullable(resourcePropertySource.get());
            }
        }

        if (propertySource.isPresent()) {
            T target;
            try {
                target = RelaxedConfigurationBinder
                        .with(clazz)
                        .setPropertySources(propertySource.get())
                        .doBind();
            } catch (GeneralException e) {
                LOGGER.error(String.format("属性绑定失败， class=%s", ClassUtils.getSimpleName(clazz)), e);
                return null;
            }
            return target;
        }
        return null;
    }

    @Override
    public void afterPropertiesSet() {
        Class<?> target = this.getClass();
        if (AopUtils.isAopProxy(this)) {
            target = AopUtils.getTargetClass(this);
        }
        LOGGER.info(String.format("%s->%s模块引入配置中心%s...", this.getModuleName(), ClassUtils.getSimpleName(target), (isCfgCenterEffect() ? "生效" : "无效")));
    }

    public String getModuleName() {
        return StringUtils.EMPTY;
    }

    @Subscribe
    public void listenRefreshEvent(ConfigCenterUtils.ConfigRefreshEvent refreshEvent) {
        if (!refreshEvent.getModuleName().equals(this.getModuleName())) {
            this.refreshForEvent();
        }
    }

    //通过事件进行刷新
    public abstract void refreshForEvent();

    //获取本地配置默认路径
    public abstract String getDefaultResourcePath();

    //获取配置属性的公共前缀
    public abstract String getConfigPrefix();
}

　　1、isCfgCenterEffect方法主要判断项目是否接入了配置中心并且配置中心配有bean中相关的属性。

　　2、binding方法主要根据isCfgCenterEffect方法的返回值去加载配置中心的properties还是本地的properties。

　　3、getDefaultResourcePath是主要是获取本地资源的默认路径（在没有接入配置中心的情况下）。

　　4、getConfigPrefix方法返回bean中配置属性的公共前缀（等同于@ConfigurationProperties中的prefix属性）。

　　5、refreshForEvent方法主要是在某个bean感知到配置中心更新属性时异步通知其他bean进行属性的更新。

bean属性绑定工具类

　　动态将propertysource绑定到带有@ConfigurationProperties注解的bean中。

　　参考 org.springframework.boot.context.properties.ConfigurationPropertiesBindingPostProcessor

public class RelaxedConfigurationBinder<T> {
    private final PropertiesConfigurationFactory<T> factory;

    public RelaxedConfigurationBinder(T object) {
        this(new PropertiesConfigurationFactory<>(object));
    }

    public RelaxedConfigurationBinder(Class<?> type) {
        this(new PropertiesConfigurationFactory<>(type));
    }

    public static <T> RelaxedConfigurationBinder<T> with(T object) {
        return new RelaxedConfigurationBinder<>(object);
    }

    public static <T> RelaxedConfigurationBinder<T> with(Class<T> type) {
        return new RelaxedConfigurationBinder<>(type);
    }

    public RelaxedConfigurationBinder(PropertiesConfigurationFactory<T> factory) {
        this.factory = factory;
        ConfigurationProperties properties = getMergedAnnotation(factory.getObjectType(), ConfigurationProperties.class);
        javax.validation.Validator validator = Validation.buildDefaultValidatorFactory().getValidator();
        factory.setValidator(new SpringValidatorAdapter(validator));
        factory.setConversionService(new DefaultConversionService());
        if (!Objects.isNull(properties)) {//NOSONAR
            factory.setIgnoreNestedProperties(properties.ignoreNestedProperties());
            factory.setIgnoreInvalidFields(properties.ignoreInvalidFields());
            factory.setIgnoreUnknownFields(properties.ignoreUnknownFields());
            factory.setTargetName(properties.prefix());
            factory.setExceptionIfInvalid(properties.exceptionIfInvalid());
        }
    }

    public RelaxedConfigurationBinder<T> setTargetName(String targetName) {
        factory.setTargetName(targetName);
        return this;
    }

    public RelaxedConfigurationBinder<T> setPropertySources(PropertySource<?>... propertySources) {
        MutablePropertySources sources = new MutablePropertySources();
        for (PropertySource<?> propertySource : propertySources) {
            sources.addLast(propertySource);
        }
        factory.setPropertySources(sources);
        return this;
    }

    public RelaxedConfigurationBinder<T> setPropertySources(Environment environment) {
        factory.setPropertySources(((ConfigurableEnvironment) environment).getPropertySources());
        return this;
    }

    public RelaxedConfigurationBinder<T> setPropertySources(PropertySources propertySources) {
        factory.setPropertySources(propertySources);
        return this;
    }

    public RelaxedConfigurationBinder<T> setConversionService(ConversionService conversionService) {
        factory.setConversionService(conversionService);
        return this;
    }

    public RelaxedConfigurationBinder<T> setValidator(Validator validator) {
        factory.setValidator(validator);
        return this;
    }

    public RelaxedConfigurationBinder<T> setResolvePlaceholders(boolean resolvePlaceholders) {
        factory.setResolvePlaceholders(resolvePlaceholders);
        return this;
    }

    public T doBind() throws GeneralException {
        try {
            return factory.getObject();
        } catch (Exception ex) {
            throw new GeneralException("配置绑定失败！", ex);
        }
    }
}

配置中心工具类

public class ConfigCenterUtils {
    private static Logger LOGGER = LoggerFactory.getLogger(ConfigCenterUtils.class);

    private static AsyncEventBus eventBus = new AsyncEventBus(Executors.newFixedThreadPool(8));//NOSONAR

    private static Properties cfgProperties;

    private static Environment environment;

    static {
        cfgProperties = new Properties();
        cfgProperties.putAll(ConfigHelper.getZookeeperPropertySource().getProperties());
    }

    public static void setEnvironment(Environment environment) {
        ConfigCenterUtils.environment = environment;
    }

    public static String getValue(String name) {
        try {
            return PropertiesUtil.getValue(name);
        } catch (Exception e) {
            LOGGER.info("配置中心无效， property name=" + name, e);
        }
        if (Objects.isNull(environment)) {
            LOGGER.info("environment无效，property name=" + name);
            return StringUtils.EMPTY;
        }
        if (!environment.containsProperty(name)) {
            LOGGER.info("environment无配置 property name=" + name);
            return StringUtils.EMPTY;
        }
        return environment.getProperty(name);
    }

    public synchronized static boolean propertySourceShouldRefresh(String moduleName, ZookeeperPropertySource newPropertySource) {
        if (!cfgProperties.equals(newPropertySource.getProperties())) {
            cfgProperties.clear();
            cfgProperties.putAll(newPropertySource.getProperties());
            eventBus.post(new ConfigRefreshEvent(moduleName));
            return true;
        }
        return false;
    }

    public static <T> T createToRefreshPropertiesBean(Class<T> clazz) {
        Enhancer enhancer = new Enhancer();
        // 设置代理对象父类
        enhancer.setSuperclass(clazz);
        // 标识Spring-generated proxies
        enhancer.setInterfaces(new Class[]{SpringProxy.class});
        // 设置增强
        enhancer.setCallback((MethodInterceptor) (target, method, args, methodProxy) -> {
            ToRefresh toRefresh = AnnotationUtils.findAnnotation(method, ToRefresh.class);
            if (Objects.isNull(toRefresh) || StringUtils.isBlank(toRefresh.method())) {
                return methodProxy.invokeSuper(target, args);
            }
            Method refreshMethod = ReflectionUtils.findMethod(target.getClass(), toRefresh.method());
            if (Objects.isNull(refreshMethod)) {
                return methodProxy.invokeSuper(target, args);
            }
            refreshMethod = BridgeMethodResolver.findBridgedMethod(refreshMethod);
            refreshMethod.setAccessible(true);
            refreshMethod.invoke(target, null);
            return methodProxy.invokeSuper(target, args);
        });

        T target = (T) enhancer.create();// 创建代理对象

        MethodIntrospector.selectMethods(clazz, (ReflectionUtils.MethodFilter) method -> AnnotatedElementUtils.isAnnotated(method, ToInitial.class))
                .stream().findFirst().ifPresent(method -> {
            method.setAccessible(true);
            try {
                method.invoke(target, null);
            } catch (Exception e) {
                LOGGER.error(String.format("初始化异常，class=%s ...", ClassUtils.getSimpleName(clazz)), e);
            }
        });

        return target;
    }

    public static void registerListener(BaseConfigCenterBean refreshableBean) {
        eventBus.register(refreshableBean);
    }

    public static class ConfigRefreshEvent {
        private String moduleName;

        public ConfigRefreshEvent(String moduleName) {
            this.moduleName = moduleName;
        }

        public String getModuleName() {
            return moduleName;
        }

        public void setModuleName(String moduleName) {
            this.moduleName = moduleName;
        }
    }
}

　　这个工具主要作用：

　　1、判断配置中心的属性是否发生了变化

　　2、为BaseConfigCenterBean子类创建代理类，使属性在getter方法时检测属性是否应该刷新。

　　3、提供将BaseConfigCenterBean类型的对象的注册为guava eventbus的监听对象，使之具有根据刷新事件自动刷新自身属性。

bean后置处理器

public class ConfigCenterBeanPostProcessor implements BeanPostProcessor {
    @Override
    public Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException {
        if (AnnotatedElementUtils.isAnnotated(bean.getClass(), ConfigCenterBean.class)) {
            BaseConfigCenterBean refreshableBean = (BaseConfigCenterBean) ConfigCenterUtils.createToRefreshPropertiesBean(bean.getClass());
            ConfigCenterUtils.registerListener(refreshableBean);
            return refreshableBean;
        }
        return bean;
    }

    @Override
    public Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException {
        return bean;
    }
}

　　该后置处理器的作用是对所有BaseConfigCenterBean类型的bean进行处理，生成代理bean，并注册为guava eventbus相应的listener。

pojo属性绑定配置中心优雅方案1

@ConfigCenterBean
@ConfigurationProperties(prefix = "wx.temporary.qrcode")
@Component
public class QrcodeConstants extends BaseConfigCenterBean {

    private static Logger LOGGER = LoggerFactory.getLogger(QrcodeConstants.class);

    //渠道
    @ConfigField //标识该属性来自配置中心
    private List<Scene> channels;

    //业务
    @ConfigField
    private List<Scene> bizs;

    //业务和渠道映射关系
    @ConfigField
    private Map<String, String> biz2Channel;

    private Map<String, Scene> channelMap;

    private Map<String, Scene> bizMap;

    public List<Scene> getChannels() {
        return channels;
    }

    public void setChannels(List<Scene> channels) {
        this.channels = channels;
    }

    public List<Scene> getBizs() {
        return bizs;
    }

    public void setBizs(List<Scene> bizs) {
        this.bizs = bizs;
    }

    @ToRefresh(method = "toRefresh")
    public Map<String, Scene> getChannelMap() {
        return channelMap;
    }

    @ToRefresh(method = "toRefresh")
    public Map<String, Scene> getBizMap() {
        return bizMap;
    }

    @ToRefresh(method = "toRefresh")
    public Map<String, String> getBiz2Channel() {
        return biz2Channel;
    }

    public void setBiz2Channel(Map<String, String> biz2Channel) {
        this.biz2Channel = biz2Channel;
    }

    @ToInitial
    private void refreshQrcodeProperties() {
        try {
            super.doBind();

            //属性处理
            if (CollectionUtils.isEmpty(channels)) {
                this.channelMap = Maps.newHashMap();
            } else {
                this.channelMap = channels.stream()
                        .collect(Collectors.toMap(channel -> channel.getType(), Function.identity()));
            }

            if (CollectionUtils.isEmpty(bizs)) {
                this.bizMap = Maps.newHashMap();
            } else {
                this.bizMap = bizs.stream()
                        .collect(Collectors.toMap(biz -> biz.getType(), Function.identity()));
            }

            LOGGER.info(String.format("%s 刷新成功..., 当前配置=%s...", this.getModuleName(), this));
        } catch (Exception e) {
            LOGGER.error("QrcodeConstants 对象属性绑定失败...", e);
        }
    }

    private void toRefresh() {
        try {
            if (isCfgCenterEffect()) {
                ZookeeperPropertySource propertySource = ConfigHelper.getZookeeperPropertySource();
                if (ConfigCenterUtils.propertySourceShouldRefresh(this.getModuleName(), propertySource)) {
                    this.refreshQrcodeProperties();
                }
            }
        } catch (Exception e) {
            LOGGER.error("QrcodeConstants 对象属性刷新失败", e);
        }
    }

    //刷新事件调用
    @Override
    public void refreshForEvent() {
        this.refreshQrcodeProperties();
    }

  //本地资源文件
    @Override
    public String getDefaultResourcePath() {
        return "config/qrcode.properties";
    }

  //属性配置 公共前缀（和@ConfigurationProperties prefix 属性一致）
    @Override
    public String getConfigPrefix() {
        return "wx.temporary.qrcode";
    }

  //模块名称
    @Override
    public String getModuleName() {
        return "微信临时二维码配置";
    }

    @Override
    public String toString() {
        return ReflectionToStringBuilder.toString(this
                , ToStringStyle.JSON_STYLE
                , false
                , false
                , QrcodeConstants.class);
    }

    public static class Scene {
        private String type;
        private String desc;

        public String getType() {
            return type;
        }

        public void setType(String type) {
            this.type = type;
        }

        public String getDesc() {
            return desc;
        }

        public void setDesc(String desc) {
            this.desc = desc;
        }

        @Override
        public String toString() {
            return ReflectionToStringBuilder.toString(this
                    , ToStringStyle.JSON_STYLE
                    , false
                    , false
                    , Scene.class);
        }
    }
}

pojo属性绑定配置中心优雅方案2

@ConfigCenterBean
@Component
public class QrcodeConstants extends BaseConfigCenterBean {

    private static Logger LOGGER = LoggerFactory.getLogger(QrcodeConstants.class);

    //业务和渠道映射关系
    private Map<String, String> biz2Channel;

    //渠道
    private Map<String, Scene> channelMap;

    //业务
    private Map<String, Scene> bizMap;

    private QrcodeProperties qrcodeProperties;

    @ToRefresh(method = "toRefresh")
    public Map<String, Scene> getChannelMap() {
        return channelMap;
    }

    @ToRefresh(method = "toRefresh")
    public Map<String, Scene> getBizMap() {
        return bizMap;
    }

    @ToRefresh(method = "toRefresh")
    public Map<String, String> getBiz2Channel() {
        return biz2Channel;
    }

    public void setBiz2Channel(Map<String, String> biz2Channel) {
        this.biz2Channel = biz2Channel;
    }

    public QrcodeProperties getRawQrcodeProperties() {
        return qrcodeProperties;
    }

    @ToInitial
    private void refreshQrcodeProperties() {
        try {
            QrcodeProperties qrcodeProperties = super.doBind(QrcodeProperties.class);
            if (Objects.isNull(qrcodeProperties)) {
                LOGGER.error(String.format("没有加载到%s配置，请检查配置...", this.getModuleName()));
                return;
            }

            this.qrcodeProperties = qrcodeProperties;

            //属性处理
            if (CollectionUtils.isEmpty(qrcodeProperties.channels)) {
                this.channelMap = Maps.newHashMap();
            } else {
                this.channelMap = qrcodeProperties.channels.stream()
                        .collect(Collectors.toMap(channel -> channel.getType(), Function.identity()));
            }

            if (CollectionUtils.isEmpty(qrcodeProperties.bizs)) {
                this.bizMap = Maps.newHashMap();
            } else {
                this.bizMap = qrcodeProperties.bizs.stream()
                        .collect(Collectors.toMap(biz -> biz.getType(), Function.identity()));
            }

            if (CollectionUtils.isEmpty(qrcodeProperties.getBiz2Channel())) {
                this.biz2Channel = Maps.newHashMap();
            } else {
                this.biz2Channel = qrcodeProperties.getBiz2Channel();
            }

            LOGGER.info(String.format("%s 刷新成功..., 当前配置=%s...", this.getModuleName(), this));
        } catch (Exception e) {
            LOGGER.error("QrcodeConstants 对象属性绑定失败...", e);
        }
    }

    private void toRefresh() {
        try {
            if (isCfgCenterEffect()) {
                ZookeeperPropertySource propertySource = ConfigHelper.getZookeeperPropertySource();
                if (ConfigCenterUtils.propertySourceShouldRefresh(this.getModuleName(), propertySource)) {
                    this.refreshQrcodeProperties();
                }
            }
        } catch (Exception e) {
            LOGGER.error("QrcodeConstants 对象属性刷新失败", e);
        }
    }

    @Override
    public void refreshForEvent() {
        this.refreshQrcodeProperties();
    }

    @Override
    public String getDefaultResourcePath() {
        return "config/qrcode.properties";
    }

    @Override
    public String getConfigPrefix() {
        return "wx.temporary.qrcode";
    }

    @Override
    public String getModuleName() {
        return "微信临时二维码配置";
    }

    @Override
    public String toString() {
        return new ToStringBuilder(this)
                .append("biz2Channel", biz2Channel)
                .append("channelMap", channelMap)
                .append("bizMap", bizMap)
                .toString();
    }

    @ConfigurationProperties(prefix = "wx.temporary.qrcode")
    public static class QrcodeProperties {
        //渠道
        private List<Scene> channels;

        //业务
        private List<Scene> bizs;

        //业务和渠道映射关系
        private Map<String, String> biz2Channel;

        public List<Scene> getChannels() {
            return channels;
        }

        public void setChannels(List<Scene> channels) {
            this.channels = channels;
        }

        public List<Scene> getBizs() {
            return bizs;
        }

        public void setBizs(List<Scene> bizs) {
            this.bizs = bizs;
        }

        public Map<String, String> getBiz2Channel() {
            return biz2Channel;
        }

        public void setBiz2Channel(Map<String, String> biz2Channel) {
            this.biz2Channel = biz2Channel;
        }
    }

    public static class Scene {
        private String type;
        private String desc;

        public String getType() {
            return type;
        }

        public void setType(String type) {
            this.type = type;
        }

        public String getDesc() {
            return desc;
        }

        public void setDesc(String desc) {
            this.desc = desc;
        }

        @Override
        public String toString() {
            return ReflectionToStringBuilder.toString(this
                    , ToStringStyle.JSON_STYLE
                    , false
                    , false
                    , Scene.class);
        }
    }
}

　　方案1和方案2略有不同，针对一些属性，我们需要做一些逻辑处理。方案1中将源属性和逻辑之后的属性都放在了同一类中，方案二则是将源属性单独放到一个静态类中，最终处理过后的属性放在了目标类中。另外二者的doBind方法也是有区别的，仔细看一下BaseConfigCenterBean这个类就可以了。

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　 参考文章：算法和技术SHARING