GoF23 代理模式学习笔记-优快云博客

本文链接：https://blog.youkuaiyun.com/Aetherzzz/article/details/115490455

本文介绍了Java中代理模式的两种实现方式：静态代理和动态代理。在静态代理中，通过创建一个代理类来扩展目标类的功能，如在租房业务中增加了看房、签约和收费的步骤。而在动态代理中，利用Java的反射机制，动态地生成代理类，同样实现了对目标类行为的增强。这两种代理模式在实际开发中常用于权限控制、日志记录等功能的添加。

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GoF23 代理模式学习笔记

静态代理

package proxy;

public interface Rent {
	void rent();
}

package proxy;

public class Host implements Rent{

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

}

package proxy;

public class Proxy {
	private Host host;

	public Proxy() {
	}

	public Proxy(Host host) {
		this.host = host;
	}
	
	public void rent() {
		viewHouse();
		host.rent();
		signContract();
		charge();
	}
	
	public void viewHouse() {
		System.out.println("view houses in advance");
	}
	
	public void signContract() {
		System.out.println("sign a contract");
	}
	
	public void charge() {
		System.out.println("charge");
	}
}

package proxy;

public class Client {
	public static void main(String[] args) {
		Proxy proxy = new Proxy(new Host());
		proxy.rent();
	}
}

动态代理

package proxy.dynamic_proxy;

public interface Rent {
	void rent();
}

package proxy.dynamic_proxy;

public class Host implements Rent{

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

}

package proxy.dynamic_proxy;

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

public class ProxyInvocationHandler implements InvocationHandler{
	
	// 被代理的接口
	private Object target;
	
	public void setTarget(Object target) {
		this.target = target;
	}
	
	// 生成得到代理类
	public Object getProxy() {
		return Proxy.newProxyInstance(this.getClass().getClassLoader(), target.getClass().getInterfaces(), this);
	}

	// 处理代理实例返回结果
	@Override
	public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
		Object result = method.invoke(target, args);
		return result;
	}
}

package proxy.dynamic_proxy;

public class Client {

	public static void main(String[] args) {
		Host host = new Host();
		ProxyInvocationHandler proxyInvocationHandler = new ProxyInvocationHandler();
		proxyInvocationHandler.setTarget(host);
		Rent proxy = (Rent)proxyInvocationHandler.getProxy();
		proxy.rent();
	}

}