代理模式

代理模式：为其他对象提供一种代理以控制对这个对象的访问。

1，静态代理

硬编码编写代理类，容易产生大量代理类（摘自网上）

//代理接口
public interface GiveGift
{
    void giveDolls();

    void giveFlowers();

    void giveChocolate();
}
//追求者类
public class Pursuit implements GiveGift
{
    SchoolGirl    mm;

    public Pursuit(SchoolGirl mm)
    {
        this.mm = mm;
    }

    public void giveDolls()
    {
        System.out.println(mm.name + " 送你洋娃娃");
    }

    public void giveFlowers()
    {
        System.out.println(mm.name + " 送你鲜花");
    }

    public void giveChocolate()
    {
        System.out.println(mm.name + " 送你巧克力");
    }
}
//代理类
public class Proxy implements GiveGift
{
    Pursuit    gg;

    public Proxy(SchoolGirl mm)
    {
        gg = new Pursuit(mm);
    }

    public void giveChocolate()
    {
        gg.giveChocolate();
    }

    public void giveDolls()
    {
        gg.giveDolls();
    }

    public void giveFlowers()
    {
        gg.giveFlowers();
    }
}
//客户端代码
public class Main
{
    public static void main(String[] args)
    {
        SchoolGirl jiaojiao = new SchoolGirl();
        jiaojiao.setName("李娇娇");

        Proxy daili = new Proxy(jiaojiao);
        daili.giveDolls();
        daili.giveFlowers();
        daili.giveChocolate();
    }
}

2，动态代理

java中有接口InvocationHandler（java.lang.reflect）

通过实现一个InvocationHandler，产生一个动态代理类。

编写一个接口如下：

public interface Subject {
	public void doSomething();
}

　实现接口：

public class RealSubject  implements Subject{

	@Override
	public void doSomething() {
		// TODO Auto-generated method stub
		System.out.println("call doSomething");
	}

　　编写动态代理类：

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

public class ProxyHandler implements InvocationHandler {

    private Object proxied;

    public ProxyHandler(Object proxied) {
            this.proxied=proxied;
    }

    @Override
    public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
        // TODO Auto-generated method stub
        
        System.out.println("开始执行");
        Object obj= method.invoke(proxied, args);
        System.out.println("结束执行");
        return obj;
    }

}

client调用：

import java.lang.reflect.Proxy;

public class DynamicProxy {

    public static void main(String[] args) {

        RealSubject real=new RealSubject();
        
        Subject proxySubject=(Subject)Proxy.newProxyInstance(Subject.class.getClassLoader(), new Class[]{Subject.class}, new ProxyHandler(new RealSubject()));
        
        proxySubject.doSomething();
        
        System.out.println(Proxy.isProxyClass(proxySubject.getClass()));    

    }

}