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设计模式-代理模式
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‎DesignPattern/src/main/java/com/design/proxy/Media.java

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package com.design.proxy;
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/**
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* 媒体接口
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*/
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public interface Media {
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void play(String file);
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}

‎DesignPattern/src/main/java/com/design/proxy/MovieMedia.java

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package com.design.proxy;
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/**
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* 直接的电影媒体类
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*/
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public class MovieMedia {
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public void play(String file) {
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System.out.println("Play Movie: " + file);
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}
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}

‎DesignPattern/src/main/java/com/design/proxy/MusicMediaImpl.java

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package com.design.proxy;
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/**
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* 实现媒体接口 - 音乐媒体
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*/
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public class MusicMediaImpl implements Media {
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@Override
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public void play(String file) {
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System.out.println("Play Music: " + file);
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}
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}

‎DesignPattern/src/main/java/com/design/proxy/v1/Main.java

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package com.design.proxy.v1;
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import com.design.proxy.Media;
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import com.design.proxy.MusicMediaImpl;
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/**
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* 静态代理事先知道要代理的是什么，目标角色固定不灵活
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*
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* @author wliduo[i@dolyw.com]
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* @date 2023/1/31 16:41
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*/
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public class Main {
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public static void main(String[] args) {
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// 组合嵌套多个代理类
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Media musicMedia = new MusicMediaImpl();
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// musicMedia.play("音乐");
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Media proxyMedia = new ProxyMediaImpl(musicMedia);
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// proxyMedia.play("音乐");
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Media timeProxyMedia = new TimeProxyMediaImpl(proxyMedia);
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timeProxyMedia.play("音乐");
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}
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}

‎DesignPattern/src/main/java/com/design/proxy/v1/ProxyMediaImpl.java

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package com.design.proxy.v1;
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import com.design.proxy.Media;
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/**
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* 静态代理一
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*
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* @author wliduo[i@dolyw.com]
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* @date 2023/1/31 16:43
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*/
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public class ProxyMediaImpl implements Media {
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Media media;
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public ProxyMediaImpl(Media media) {
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this.media = media;
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}
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@Override
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public void play(String file) {
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System.out.println("Start");
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media.play(file);
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System.out.println("End");
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}
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}

‎DesignPattern/src/main/java/com/design/proxy/v1/TimeProxyMediaImpl.java

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package com.design.proxy.v1;
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import com.design.proxy.Media;
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/**
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* 静态代理二
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*
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* @author wliduo[i@dolyw.com]
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* @date 2023/1/31 16:43
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*/
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public class TimeProxyMediaImpl implements Media {
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Media media;
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public TimeProxyMediaImpl(Media media) {
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this.media = media;
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}
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@Override
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public void play(String file) {
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System.out.println(System.currentTimeMillis());
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media.play(file);
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System.out.println(System.currentTimeMillis());
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}
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}

‎DesignPattern/src/main/java/com/design/proxy/v2/CglibDynamicProxy.java

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package com.design.proxy.v2;
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import com.design.proxy.MovieMedia;
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import com.design.proxy.MusicMediaImpl;
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import org.springframework.cglib.proxy.Enhancer;
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import org.springframework.cglib.proxy.MethodInterceptor;
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import org.springframework.cglib.proxy.MethodProxy;
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import java.lang.reflect.Method;
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/**
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* CGLib必须依赖于CGLib的类库，需要满足以下要求
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* 1. 实现MethodInterceptor接口，重写intercept()
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* 2. 使用Enhancer对象.create()产生代理对象
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* 3. 因为是继承机制，不能代理final修饰的类
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*
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* CGLIB则使用的继承机制，针对类实现代理，被代理类和代理类是继承关系，所以代理类是可以赋值给被代理类的
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* CGLIB代理使用字节码处理框架asm，对代理对象类的class文件加载进来，通过修改字节码生成子类
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* CGLIB创建代理对象效率较低，执行效率高
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*
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* @author wliduo[i@dolyw.com]
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* @date 2023/1/31 16:52
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*/
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public class CglibDynamicProxy implements MethodInterceptor {
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/**
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* 代理的目标对象
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*/
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private Object object;
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public CglibDynamicProxy(Object object) {
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this.object = object;
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}
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public Object proxy() {
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Class<?> clazz = object.getClass();
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// 生成代理对象
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Enhancer enhancer = new Enhancer();
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enhancer.setSuperclass(clazz);
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enhancer.setCallback(this);
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return enhancer.create();
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}
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@Override
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public Object intercept(Object proxy, Method method, Object[] objects, MethodProxy methodProxy) throws Throwable {
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System.out.println(proxy.getClass().getSuperclass().getName());
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beforeMethod(object);
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Object result = methodProxy.invokeSuper(proxy, objects);
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afterMethod(object);
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return result;
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}
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private void beforeMethod(Object object) {
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if (object instanceof MusicMediaImpl) {
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System.out.println("MusicMediaImpl Start");
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} else if (object instanceof MovieMedia) {
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System.out.println("MovieMedia Start");
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} else {
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throw new RuntimeException("暂不支持代理" + object.getClass() + "类型");
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}
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}
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private void afterMethod(Object object) {
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if (object instanceof MusicMediaImpl) {
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System.out.println("MusicMediaImpl End");
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} else if (object instanceof MovieMedia) {
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System.out.println("MovieMedia End");
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} else {
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throw new RuntimeException("暂不支持代理" + object.getClass() + "类型");
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}
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}
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}

‎DesignPattern/src/main/java/com/design/proxy/v2/JdkDynamicProxy.java

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package com.design.proxy.v2;
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import com.design.proxy.MovieMedia;
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import com.design.proxy.MusicMediaImpl;
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import java.lang.reflect.InvocationHandler;
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import java.lang.reflect.Method;
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import java.lang.reflect.Proxy;
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/**
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* JDK代理是不需要依赖第三方的库，只要JDK环境就可以进行代理，需要满足以下要求
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* 1. 实现InvocationHandler接口，重写invoke()
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* 2. 使用Proxy.newProxyInstance()产生代理对象
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* 3. 被代理的对象必须要实现接口
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*
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* JDK动态代理机制是委托机制，只能对实现接口的类生成代理，通过反射动态实现接口类
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* JDK代理使用的是反射机制生成一个实现代理接口的匿名类，在调用具体方法前调用InvokeHandler来处理
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* JDK创建代理对象效率较高，执行效率较低
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*
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* @author wliduo[i@dolyw.com]
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* @date 2023/1/31 16:52
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*/
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public class JdkDynamicProxy implements InvocationHandler {
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/**
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* 代理的目标对象
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*/
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private Object object;
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public JdkDynamicProxy(Object object) {
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this.object = object;
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}
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public Object proxy() {
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Class<?> clazz = object.getClass();
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// 生成代理对象
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return Proxy.newProxyInstance(clazz.getClassLoader(), clazz.getInterfaces(), this);
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}
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@Override
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public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
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beforeMethod(object);
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Object result = method.invoke(object, args);
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afterMethod(object);
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return result;
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}
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private void beforeMethod(Object object) {
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if (object instanceof MusicMediaImpl) {
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System.out.println("MusicMediaImpl Start");
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} else if (object instanceof MovieMedia) {
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System.out.println("MovieMedia Start");
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} else {
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throw new RuntimeException("暂不支持代理" + object.getClass() + "类型");
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}
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}
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private void afterMethod(Object object) {
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if (object instanceof MusicMediaImpl) {
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System.out.println("MusicMediaImpl End");
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} else if (object instanceof MovieMedia) {
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System.out.println("MovieMedia End");
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} else {
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throw new RuntimeException("暂不支持代理" + object.getClass() + "类型");
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}
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}
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}

‎DesignPattern/src/main/java/com/design/proxy/v2/Main.java

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package com.design.proxy.v2;
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import com.design.proxy.Media;
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import com.design.proxy.MovieMedia;
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import com.design.proxy.MusicMediaImpl;
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/**
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* 相比于静态代理，动态代理在创建代理对象上更加的灵活
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*
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* 验证一，音乐媒体类实现接口都可以成功代理
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*
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* @author wliduo[i@dolyw.com]
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* @date 2023/1/31 16:55
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*/
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public class Main {
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public static void main(String[] args) {
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Media musicMedia = new MusicMediaImpl();
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// musicMedia.play("音乐");
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// 使用Jdk动态代理接口实现方式
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JdkDynamicProxy jdkDynamicProxy = new JdkDynamicProxy(musicMedia);
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Media jdkDynamicProxyMedia = (Media) jdkDynamicProxy.proxy();
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jdkDynamicProxyMedia.play("Jdk音乐");
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System.out.println("----------");
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// 使用Cglib动态代理接口实现方式
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CglibDynamicProxy cglibDynamicProxy = new CglibDynamicProxy(musicMedia);
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Media cglibDynamicProxyMedia = (Media) cglibDynamicProxy.proxy();
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cglibDynamicProxyMedia.play("Cglib音乐");
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}
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}

‎DesignPattern/src/main/java/com/design/proxy/v2/Main2.java

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package com.design.proxy.v2;
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import com.design.proxy.MovieMedia;
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/**
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* 相比于静态代理，动态代理在创建代理对象上更加的灵活
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*
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* 验证二，电影媒体类未实现接口只有Cglib可以代理
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*
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* @author wliduo[i@dolyw.com]
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* @date 2023/1/31 16:55
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*/
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public class Main2 {
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public static void main(String[] args) {
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MovieMedia movieMedia = new MovieMedia();
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// movieMedia.play("电影");
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// 使用Cglib动态代理Class类
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CglibDynamicProxy cglibDynamicProxy = new CglibDynamicProxy(movieMedia);
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MovieMedia cglibDynamicProxyMedia = (MovieMedia) cglibDynamicProxy.proxy();
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cglibDynamicProxyMedia.play("Cglib电影");
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System.out.println("----------");
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// 使用Jdk动态代理Class类，运行失败，Jdk必须实现接口才可以代理
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JdkDynamicProxy jdkDynamicProxy = new JdkDynamicProxy(movieMedia);
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MovieMedia jdkDynamicProxyMedia = (MovieMedia) jdkDynamicProxy.proxy();
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jdkDynamicProxyMedia.play("Jdk电影");
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}
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}

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