Java基础-SSM之Spring的AOP编程

　　　　　　　　　　　　Java基础-SSM之Spring的AOP编程

　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　作者：尹正杰

版权声明：原创作品，谢绝转载！否则将追究法律责任。

　　  Spring的本质说白了就是动态代理，接下来我们会体验AOP的用法。它是对OOP的增强，适用于系统级功能。

 一.MethodBeforeAdvice接口的应用

1>.引入新的依赖

 <?xml version="1.0" encoding="UTF-8"?>
 <project xmlns="http://maven.apache.org/POM/4.0.0"
          xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
          xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
     <modelVersion>4.0.0</modelVersion>

     <groupId>cn.org.yinzhengjie</groupId>
     <artifactId>MySpring</artifactId>
     <version>1.0-SNAPSHOT</version>

     <dependencies>
         <dependency>
             <groupId>junit</groupId>
             <artifactId>junit</artifactId>
             <version>4.11</version>
         </dependency>
         <dependency>
             <groupId>org.springframework</groupId>
             <artifactId>spring-context-support</artifactId>
             <version>4.3.5.RELEASE</version>
         </dependency>

         <dependency>
             <groupId>aopalliance</groupId>
             <artifactId>aopalliance</artifactId>
             <version>1.0</version>
         </dependency>
     </dependencies>

 </project>

2>.定义通知类

 /*
 @author :yinzhengjie
 Blog:http://www.cnblogs.com/yinzhengjie/tag/Java%E5%9F%BA%E7%A1%80/
 EMAIL:y1053419035@qq.com
 */
 package cn.org.yinzhengjie.spring.aop.advice;

 import org.springframework.aop.MethodBeforeAdvice;

 import java.lang.reflect.Method;

 /**
  * 前置通知
  */
 public class MyMethodBeforeAdvice implements MethodBeforeAdvice {
     public void before(Method method, Object[] args, Object target) throws Throwable {
         String mname = method.getName() ;
         System.out.printf("当前处理的对象 : %s\n调用对象的方法 : %s\n调用参数 : %s\n" , target.toString(),mname.toString(),args.toString());
         System.out.println("============= MyMethodBeforeAdvice代码执行完毕 =============");
     }
 }

3>.编写实现WelcomeService和WelcomeService2两个接口的类

 /*
 @author :yinzhengjie
 Blog:http://www.cnblogs.com/yinzhengjie/tag/Java%E5%9F%BA%E7%A1%80/
 EMAIL:y1053419035@qq.com
 */
 package cn.org.yinzhengjie.spring.aop.advice;

 public interface WelcomeService {
     public abstract void sayHello();
 }

WelcomeService.java 文件内容

 /*
 @author :yinzhengjie
 Blog:http://www.cnblogs.com/yinzhengjie/tag/Java%E5%9F%BA%E7%A1%80/
 EMAIL:y1053419035@qq.com
 */
 package cn.org.yinzhengjie.spring.aop.advice;

 public interface WelcomeService2 {
     public abstract void sayHello2();
 }

WelcomeService2.java 文件内容

 /*
 @author :yinzhengjie
 Blog:http://www.cnblogs.com/yinzhengjie/tag/Java%E5%9F%BA%E7%A1%80/
 EMAIL:y1053419035@qq.com
 */
 package cn.org.yinzhengjie.spring.aop.advice;

 public class WelcomeServiceImpl implements WelcomeService,WelcomeService2{
     private String name ;

     public String getName() {
         return name;
     }

     public void setName(String name) {
         this.name = name;
     }

     public void sayHello() {
         System.out.println(name);
     }

     public void sayHello2() {
         System.out.println("Hello Wold");
     }
 }

4>.编写Spring的配置文件

 <?xml version="1.0"?>
 <beans xmlns="http://www.springframework.org/schema/beans"
        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
        xmlns:aop="http://www.springframework.org/schema/aop"
        xmlns:context="http://www.springframework.org/schema/context"
        xmlns:tx="http://www.springframework.org/schema/tx"
        xsi:schemaLocation="http://www.springframework.org/schema/beans
                                 http://www.springframework.org/schema/beans/spring-beans-4.3.xsd
                                 http://www.springframework.org/schema/aop
                                 http://www.springframework.org/schema/aop/spring-aop-4.3.xsd
                                 http://www.springframework.org/schema/context
                                 http://www.springframework.org/schema/context/spring-context-4.3.xsd
                                 http://www.springframework.org/schema/tx
                                 http://www.springframework.org/schema/tx/spring-tx-4.3.xsd">
     <!-- 前置通知 -->
     <bean id="beforeAdvice" class="cn.org.yinzhengjie.spring.aop.advice.MyMethodBeforeAdvice" />

     <!-- 目标对象 -->
     <bean id="wsTarget" class="cn.org.yinzhengjie.spring.aop.advice.WelcomeServiceImpl">
         <property name="name" value="I'm yinzhengjie !!!" />
     </bean>

     <!-- 代理对象 -->
     <bean id="wsProxy" class="org.springframework.aop.framework.ProxyFactoryBean">
         <!-- 代理接口集 -->
         <property name="proxyInterfaces">
             <list>
                 <value>cn.org.yinzhengjie.spring.aop.advice.WelcomeService</value>
                 <value>cn.org.yinzhengjie.spring.aop.advice.WelcomeService2</value>
             </list>
         </property>
         <!-- 拦截器名集合 -->
         <property name="interceptorNames">
             <list>
                 <value>beforeAdvice</value>
             </list>
         </property>

         <!-- 注意，目标类的名字为"target"关键字，而ref是真正需要被代理的对象连接。一个代理对象一次性只能代理一个类，如果想要代理多个类，需要重新单独定义bean标签哟！ -->
         <property name="target" ref="wsTarget" />

     </bean>
 </beans>

5>.编写单元测试类代码

 /*
 @author :yinzhengjie
 Blog:http://www.cnblogs.com/yinzhengjie/tag/Java%E5%9F%BA%E7%A1%80/
 EMAIL:y1053419035@qq.com
 */
 package cn.org.yinzhengjie.spring.aop.advice;

 import org.junit.Test;
 import org.springframework.context.ApplicationContext;
 import org.springframework.context.support.ClassPathXmlApplicationContext;

 public class TestAop {
     @Test
     public void testAOP1(){
         ApplicationContext ac = new ClassPathXmlApplicationContext("aop.xml") ;
         WelcomeService ws = (WelcomeService) ac.getBean("wsProxy");
         ws.sayHello();

         WelcomeService2 ws2 = (WelcomeService2)ws;
         ws2.sayHello2();

     }
 }

　　以上代码测试结果如下：

二.AOP的四个通知编程案例

　　上面我们已经介绍了Spring的AOP编程中的一个前置通知，其实除了前置通知还有后置通知，循环通知以及异常通知。其实配置文件的方法和上面类似，只不过他们有各自的优点，下面我简单的做个介绍：

　　　　前置通知：主要负责处理调用目标对象之前执行的代码；

　　　　后置通知：主要负责处理调用目标对象之后的执行代码；

　　　　环绕通知：它执行的优先级是在后置通知之前，在前置通知之后的执行的代码，它可以把方法包起来处理，比如在调用方法之前执行一段代码，在调用方法之后，还可以执行一段代码，另外，相比前置通知和通知通知，它还新增了一个返回值的功能；

　　　　异常通知：它执行的优先级暂时没法确定，而且不一定执行，顾名思义，它是在有异常的时候才会触发的代码！因此即使你写了这样的通知，有可能你看不到它的执行结果，除非你故意写一段可能出现异常的代码；

1>.编写测试代码

 /*
 @author :yinzhengjie
 Blog:http://www.cnblogs.com/yinzhengjie/tag/Java%E5%9F%BA%E7%A1%80/
 EMAIL:y1053419035@qq.com
 */
 package cn.org.yinzhengjie.spring.aop.advice;

 public interface WelcomeService {
     public abstract void sayHello();
 }

WelcomeService.java 文件内容

 /*
 @author :yinzhengjie
 Blog:http://www.cnblogs.com/yinzhengjie/tag/Java%E5%9F%BA%E7%A1%80/
 EMAIL:y1053419035@qq.com
 */
 package cn.org.yinzhengjie.spring.aop.advice;

 public interface WelcomeService2 {
     public abstract void sayHello2();
 }

WelcomeService2.java 文件内容

 /*
 @author :yinzhengjie
 Blog:http://www.cnblogs.com/yinzhengjie/tag/Java%E5%9F%BA%E7%A1%80/
 EMAIL:y1053419035@qq.com
 */
 package cn.org.yinzhengjie.spring.aop.advice;

 public class WelcomeServiceImpl implements WelcomeService,WelcomeService2{
     private String name ;

     public String getName() {
         return name;
     }

     public void setName(String name) {
         this.name = name;
     }

     public void sayHello() {
         System.out.println(name);
     }

     public void sayHello2() {
         System.out.println("Hello Wold");
     }
 }

WelcomeServiceImpl.java 文件内容

2>.编写通知类

 /*
 @author :yinzhengjie
 Blog:http://www.cnblogs.com/yinzhengjie/tag/Java%E5%9F%BA%E7%A1%80/
 EMAIL:y1053419035@qq.com
 */
 package cn.org.yinzhengjie.spring.aop.advice;

 import org.springframework.aop.MethodBeforeAdvice;

 import java.lang.reflect.Method;

 /**
  * 前置通知
  */
 public class MyMethodBeforeAdvice implements MethodBeforeAdvice {
     public void before(Method method, Object[] args, Object target) throws Throwable {
         String mname = method.getName() ;
         System.out.printf("当前处理的对象 : %s\n调用对象的方法 : %s\n调用参数 : %s\n" , target.toString(),mname.toString(),args.toString());
         System.out.println("============= MyMethodBeforeAdvice代码执行完毕 =============");
     }
 }

MyMethodBeforeAdvice.java 文件内容

 /*
 @author :yinzhengjie
 Blog:http://www.cnblogs.com/yinzhengjie/tag/Java%E5%9F%BA%E7%A1%80/
 EMAIL:y1053419035@qq.com
 */
 package cn.org.yinzhengjie.spring.aop.advice;

 import org.aopalliance.intercept.MethodInterceptor;
 import org.aopalliance.intercept.MethodInvocation;

 /**
  * 环绕通知,可以篡改行为
  */
 public class MyMethodInterceptor  implements MethodInterceptor {

     public Object invoke(MethodInvocation invocation) throws Throwable {
         System.out.println("begin");
         //调用目标对象方法的返回值
         Object tis = invocation.getThis();
         System.out.println(tis);
         Object ret = invocation.proceed() ;
         System.out.println("end");
         return ret;
     }
 }

MyMethodInterceptor.java 文件内容

 /*
 @author :yinzhengjie
 Blog:http://www.cnblogs.com/yinzhengjie/tag/Java%E5%9F%BA%E7%A1%80/
 EMAIL:y1053419035@qq.com
 */
 package cn.org.yinzhengjie.spring.aop.advice;

 import org.springframework.aop.AfterReturningAdvice;

 import java.lang.reflect.Method;

 public class MyAfterReturningAdvice  implements AfterReturningAdvice {
     public void afterReturning(Object returnValue, Method method, Object[] args, Object target) throws Throwable {
         System.out.println("over");
     }
 }

MyAfterReturningAdvice.java 文件内容

 /*
 @author :yinzhengjie
 Blog:http://www.cnblogs.com/yinzhengjie/tag/Java%E5%9F%BA%E7%A1%80/
 EMAIL:y1053419035@qq.com
 */
 package cn.org.yinzhengjie.spring.aop.advice;

 import org.springframework.aop.ThrowsAdvice;

 import java.lang.reflect.Method;

 /**
  * 异常通知
  */
 public class MyThrowableAdvice implements ThrowsAdvice {
     public void afterThrowing(Method method, Object[] args, Object target, Exception ex){
         System.out.println("出事了！！" + ex.toString());
     }
 }

MyThrowableAdvice.java 文件内容

3>.编写Spring的配置文件

 <?xml version="1.0"?>
 <beans xmlns="http://www.springframework.org/schema/beans"
        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
        xmlns:aop="http://www.springframework.org/schema/aop"
        xmlns:context="http://www.springframework.org/schema/context"
        xmlns:tx="http://www.springframework.org/schema/tx"
        xsi:schemaLocation="http://www.springframework.org/schema/beans
                         http://www.springframework.org/schema/beans/spring-beans-4.3.xsd
                         http://www.springframework.org/schema/aop
                         http://www.springframework.org/schema/aop/spring-aop-4.3.xsd
                         http://www.springframework.org/schema/context
                         http://www.springframework.org/schema/context/spring-context-4.3.xsd
                         http://www.springframework.org/schema/tx
                         http://www.springframework.org/schema/tx/spring-tx-4.3.xsd">
     <!-- 通知 -->
     <bean id="beforeAdvice" class="cn.org.yinzhengjie.spring.aop.advice.MyMethodBeforeAdvice" />
     <bean id="afterAdvice" class="cn.org.yinzhengjie.spring.aop.advice.MyAfterReturningAdvice" />
     <bean id="aroundAdvice" class="cn.org.yinzhengjie.spring.aop.advice.MyMethodInterceptor" />
     <bean id="throwableAdvice" class="cn.org.yinzhengjie.spring.aop.advice.MyThrowableAdvice" />

     <!-- 目标对象 -->
     <bean id="wsTarget" class="cn.org.yinzhengjie.spring.aop.advice.WelcomeServiceImpl">
         <property name="name" value="tom" />
     </bean>

     <!-- 代理对象 -->
     <bean id="wsProxy" class="org.springframework.aop.framework.ProxyFactoryBean">
         <!-- 代理接口集 -->
         <property name="proxyInterfaces">
             <list>
                 <value>cn.org.yinzhengjie.spring.aop.advice.WelcomeService</value>
                 <value>cn.org.yinzhengjie.spring.aop.advice.WelcomeService2</value>
             </list>
         </property>
         <!-- 拦截器名集合 -->
         <property name="interceptorNames">
             <list>
                 <value>beforeAdvice</value>
                 <value>afterAdvice</value>
                 <value>aroundAdvice</value>
                 <value>throwableAdvice</value>
             </list>
         </property>
         <property name="target" ref="wsTarget" />
     </bean>
 </beans>

4>.编写测试代码

 /*
 @author :yinzhengjie
 Blog:http://www.cnblogs.com/yinzhengjie/tag/Java%E5%9F%BA%E7%A1%80/
 EMAIL:y1053419035@qq.com
 */
 package cn.org.yinzhengjie.spring.aop.advice;

 import org.junit.Test;
 import org.springframework.context.ApplicationContext;
 import org.springframework.context.support.ClassPathXmlApplicationContext;

 public class TestAop {
     @Test
     public void testAOP1(){
         ApplicationContext ac = new ClassPathXmlApplicationContext("aop.xml") ;
         WelcomeService ws = (WelcomeService) ac.getBean("wsProxy");
         ws.sayHello();

         WelcomeService2 ws2 = (WelcomeService2)ws;
         ws2.sayHello2();

     }
 }

5>.运行以上代码执行结果如下：