Java实现的拦截器模型

/** 
* Created by IntelliJ IDEA. 
* User: leizhimin 
* Date: 2008-3-20 23:32:06 
* Company: LavaSoft([url]http://lavasoft.blog.51cto.com[/url]) 
* 业务组件接口 
*/ 
public  interface BusinessInterface { 
     public  void doSomething(); 
} 

/** 
* Created by IntelliJ IDEA. 
* User: leizhimin 
* Date: 2008-3-20 23:31:12 
* Company: LavaSoft([url]http://lavasoft.blog.51cto.com[/url]) 
* 业务组件 
*/ 
public  class BusinessClass  implements BusinessInterface{ 

     public  void doSomething() { 
        System.out.println( "业务组件BusinessClass方法调用:doSomething()"); 
    } 
}

import java.lang.reflect.InvocationHandler; 
import java.lang.reflect.Method; 
import java.lang.reflect.Proxy; 

/** 
* Created by IntelliJ IDEA. 
* User: leizhimin 
* Date: 2008-3-20 23:24:10 
* Company: LavaSoft([url]http://lavasoft.blog.51cto.com[/url]) 
* 动态代理处理器工具 
*/ 
public  class DynamicProxyHandler  implements InvocationHandler { 
     private Object business;     //被代理对象 
     private InterceptorClass interceptor =  new InterceptorClass();     //拦截器 

     /** 
     * 动态生成一个代理类对象,并绑定被代理类和代理处理器 
     * 
     * @param business 
     * @return 代理类对象 
     */ 
     public Object bind(Object business) { 
         this.business = business; 
         return Proxy.newProxyInstance( 
                 //被代理类的ClassLoader 
                business.getClass().getClassLoader(), 
                 //要被代理的接口,本方法返回对象会自动声称实现了这些接口 
                business.getClass().getInterfaces(), 
                 //代理处理器对象 
                 this); 
    } 

     /** 
     * 代理要调用的方法,并在方法调用前后调用连接器的方法. 
     * 
     * @param proxy  代理类对象 
     * @param method 被代理的接口方法 
     * @param args   被代理接口方法的参数 
     * @return 方法调用返回的结果 
     * @throws Throwable 
     */ 
     public Object invoke(Object proxy, Method method, Object[] args)  throws Throwable { 
        Object result =  null; 
        interceptor.before(); 
        result=method.invoke(business,args); 
        interceptor.after(); 
         return  null;   //To change body of implemented methods use File | Settings | File Templates. 
    } 
}

/** 
* Created by IntelliJ IDEA. 
* User: leizhimin 
* Date: 2008-3-20 23:26:31 
* Company: LavaSoft([url]http://lavasoft.blog.51cto.com[/url]) 
* 拦截器 
*/ 
public  class InterceptorClass { 
     public  void before(){ 
        System.out.println( "拦截器InterceptorClass方法调用:before()!"); 
    } 
     public  void after(){ 
        System.out.println( "拦截器InterceptorClass方法调用:after()!"); 
    } 
}

/** 
* Created by IntelliJ IDEA. 
* User: leizhimin 
* Date: 2008-3-21 0:32:55 
* Company: LavaSoft([url]http://lavasoft.blog.51cto.com[/url]) 
* 客户端 
*/ 
public  class Client { 
     public  static  void main(String args[]) { 
        DynamicProxyHandler handler =  new DynamicProxyHandler(); 
        BusinessInterface business =  new BusinessClass(); 
        BusinessInterface businessProxy = (BusinessInterface) handler.bind(business); 
        businessProxy.doSomething(); 
    } 
}