Spring AOP 本质(1)

/** 
* 被代理类 
*/ 
public  class MessageWriter{ 
     /** 
     * 业务方法 
     */ 
     public  void writeMessage() { 
        System.out.print( "World"); 
    } 
}

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

/** 
* 实现包围通知,实际就是方法拦截器,MethodInterceptor是AOP联盟定义的接口. 
*/ 
public  class MessageDecorator  implements MethodInterceptor { 

     public Object invoke(MethodInvocation invocation)  throws Throwable { 
        System.out.print( "Hello "); 
        Object retVal = invocation.proceed(); 
        System.out.println( "!"); 
         return retVal; 
    } 
}

import org.springframework.aop.framework.ProxyFactory; 

/** 
* AOP测试 
*/ 
public  class HelloWorldAOPExample { 

     public  static  void main(String[] args) { 
         //目标对象（被代理的对象） 
        MessageWriter target =  new MessageWriter(); 
         
         //产生一个代理工厂 
        ProxyFactory pf =  new ProxyFactory(); 
         //添加代理工厂的拦截器 
        pf.addAdvice( new MessageDecorator()); 
         //设置被代理对象 
        pf.setTarget(target); 

         //获取一个代理实例 
        MessageWriter proxy = (MessageWriter) pf.getProxy(); 
         
         //从目标对象直接输出信息 
        target.writeMessage(); 
        System.out.println( "\n------------"); 
         //从代理对象输出信息 
        proxy.writeMessage(); 
    } 
}

- Using JDK 1.4 collections 
World 
------------ 
Hello World! 

Process finished with exit code 0