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

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{

@Override
public void print() {
System.out.println("Printed By RealRole One.");
}

@Override
public void sayHello() {
System.out.println("Hello from RealRole One.");
}
}

package com.proxy.severalCase;

public class RealRole2 implements AbstractRole{

@Override
public void print() {
System.out.println("Printed By RealRole Two.");
}

@Override
public 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;
}

@Override
public 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：