java代理【转载】

代理模式在Spring中，运用的淋漓精致，面向切面的编程，变得很有趣

 

假设有个实际书籍供应商，网上书籍供应商，而网上书籍供应商是代理商

 

 

package
 com.study.proxy;

public
 
interface
 Subject {
    public
 
void
 sailBook();
}

 package com.study.proxy;

 

//真实卖家，最初卖家
public
 
class
 RealSubject 
implements
 Subject {

    @Override
    public
 
void
 sailBook() {
        System.out.println("卖书"
);
    }

}

网上代理商代理类：

 

package
 com.study.proxy;

import
 java.lang.reflect.InvocationHandler;
import
 java.lang.reflect.Method;
import
 java.util.Date;
//代理商
public
 
class
 MyHandler 
implements
 InvocationHandler {

    private
 Object realSub = 
null
;
    public
 
void
 setSub(Object sub){
        this
.realSub = sub;
    }

    @Override
    public
 Object invoke(Object proxy, Method method, Object[] args)
            throws
 Throwable {
        if
(
this
.realSub==
null
){
            System.out.println("你无权操作"
);
//判断权限
            return
 
null
;
        }else
{
            String dazhe = DaZhe();
            System.out.println(dazhe);
            Object rtObj = method.invoke(realSub, args);
            String give = Give();
            System.out.println(give);
            String log = dazhe+give+new
 Date();
            System.out.println(log);
            return
 rtObj;
        }

    }
    private
 String DaZhe(){
        return
 
"打折信息"
;
    }

    private
 String Give(){
        return
 
"送代金券"
;
    }

}

 

 客户端，测试类

 

package
 com.study.proxy;

import
 java.lang.reflect.Proxy;

public
 
class
 Client {

    public
 
static
 
void
 main(String[] args) {
        Subject sub = new
 RealSubject();
        MyHandler handler1 = new
 MyHandler();
        MyHandler handler2 = new
 MyHandler();
        handler1.setSub(sub);
        Subject proxySub1 = (Subject) Proxy.newProxyInstance(
                RealSubject.class
.getClassLoader(),
                RealSubject.class
.getInterfaces(), handler1);
        Subject proxySub2 = (Subject) Proxy.newProxyInstance(
                RealSubject.class
.getClassLoader(),
                RealSubject.class
.getInterfaces(), handler2);
        proxySub1.sailBook();
        proxySub2.sailBook();
    }

}