Design Pattern—— Dynamic Proxy Pattern（三）动态代理模式

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done by myself

通过下面例子，进一步演示动态代理的强大特性，将会体会到相对于静态static代理，动态可实现一个proxy代理不同的真实对象。灵活多变。只需要在Client类调整要代理的角色，无需改动其他部分。使代理角色、真实角色的对应关系更松散了。

抽象角色：

package com.proxy.severalCase;public interface AbstractRole {void print();void sayHello();
}

两个真实角色：

package com.proxy.severalCase;public class RealRole1 implements AbstractRole{@Overridepublic void print() {System.out.println("Printed By RealRole One.");}@Overridepublic void sayHello() {System.out.println("Hello from RealRole One.");}
}

package com.proxy.severalCase;public class RealRole2 implements AbstractRole{@Overridepublic void print() {System.out.println("Printed By RealRole Two.");}@Overridepublic void sayHello() {System.out.println("Hello from RealRole Two.");}
}

实现InvocationHandler的类：

package com.proxy.severalCase;import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;public class InvocationClass implements InvocationHandler {private Object proxyRole;public InvocationClass(Object o) {this.proxyRole = o;}public InvocationClass() {}public void setProxyRole(Object o) {this.proxyRole = o;}@Overridepublic Object invoke(Object proxy, Method method, Object[] args)throws Throwable {return method.invoke(proxyRole, args);}}

Client类：

package com.proxy.severalCase;import java.lang.reflect.Proxy;public class Client {public static void main(String[] args) {AbstractRole proxyRole = null; //同一个代理proxy 代理不同的真实对象InvocationClass handler = new InvocationClass();handler.setProxyRole(new RealRole1());proxyRole = (AbstractRole) Proxy.newProxyInstance(InvocationClass.class.getClassLoader(),new Class[] { AbstractRole.class }, handler);proxyRole.print();proxyRole.sayHello();System.out.println("-------------------------------");handler.setProxyRole(new RealRole2());proxyRole = (AbstractRole) Proxy.newProxyInstance(handler.getClass().getClassLoader(), proxyRole.getClass().getInterfaces(),handler);proxyRole.print();proxyRole.sayHello();}
}

输出结果：