Java代理(二)

前面说到了java的静态代理,这次来看看动态代理。

假设有如下接口和实现方法:

package proxy;

public interface Subject {
    public void request();
    public void response();
}
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package proxy;

public class RealSubject implements Subject{

    public void request() {
        System.out.println("request...");
    }

    public void response() {
        System.out.println("response...");
    }

}
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然后,需求来了,希望在执行方法前后加某个其他的操作,那么动态代理会这么做:

package proxy.dynamicProxy;


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

public class ProxyHandle implements InvocationHandler{
    private Object target;//目标对象
    public ProxyHandle(Object target){
        this.target = target;
    }
    
    public Object invoke(Object proxy, Method method, Object[] args)
            throws Throwable {
        System.out.println("before...");
        Object retrunObj = method.invoke(target, args);
        System.out.println("afeter...");
        return retrunObj;
    }
}
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然后客户端的代码会这么写:

package proxy.dynamicProxy;

import java.lang.reflect.Proxy;

import proxy.RealSubject;
import proxy.Subject;

public class DynamicProxyTestMain {

    public static void main(String[] args) {
        RealSubject subject = new RealSubject();
        Subject proxySubject = (Subject) Proxy.newProxyInstance(subject
                .getClass().getClassLoader(), subject.getClass()
                .getInterfaces(), new ProxyHandle(subject));
        proxySubject.request();
        
        //proxySubject.response();
    }

}
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从上面的代码页可以看出,一旦接口变了,代理类是不需要做改变的~~

但是java的动态代理依赖于接口,如果现有代码中没有接口怎么办,岂不是不能使用java的动态代理了??

怎么破?使用cglib...

 

 

 

posted @ 2013-08-03 11:04  yejg1212  阅读(413)  评论(0编辑  收藏  举报