静态代理

第一种实现(基于接口)：

1》接口

public interface Hello { void say(String msg);}

2》目标类，至少实现一个接口

public class HelloImpl implements Hello { public void say(String msg) { System.out.println("Hi,"+msg); }}

3》代理类(与目标类实现相同接口，从而保证功能一致)

public class HelloProxy implements Hello{ private Hello hello; public HelloProxy(Hello hello){ this.hello = hello; } public void say(String msg){ before(); hello.say(msg); after(); } private void before(){ System.out.println("Before"); } private void after(){ System.out.println("After"); }}

3》测试

/** * @Author LZHL * @Create 2017-02-19 10:26 * @Description */public class Main { public static void main(String[] args) throws Exception { HelloImpl target = new HelloImpl(); HelloProxy proxy = new HelloProxy(target); proxy.say("LZHL"); }}

第二种实现(基于目标类)：

1>目标类

public class HelloTarget { public void sayHello(String name){ System.out.println("Hi,"+name); }}

2>代理类(通过继承目标类，保证功能一致)

public class HelloProxy extends HelloTarget{　　private HelloTarget target;　　public HelloProxy(HelloTarget target){　　　　this.target = target;　　} 　　@Override public void sayHello(String name) { this.before(); target.sayHello(name); this.after(); } private void before(){ System.out.println("Before"); } private void after(){ System.out.println("After"); }}

3>测试

public class Main { public static void main(String[] args) throws Exception { HelloTarget target = new HelloTarget(); 　　　　HelloProxy proxy= new HelloProxy(target); proxy.sayHello("LZHL"); }}

动态代理

动态代理的代理类是在程序运行期间动态生成的，也有两种实现，一种是JDK动态代理，一种是CGLib动态代理

1》JDK动态代理(基于接口实现，与目标类实现相同接口，从而保证功能一致)

/** * @Author LZHL * @Create 2017-02-19 12:46 * @Description */public class Main { public static void main(String[] args){ final HelloImpl target = new HelloImpl(); Object proxyInstance = Proxy.newProxyInstance(target.getClass().getClassLoader(), target.getClass().getInterfaces(), new InvocationHandler() { /* * proxy: 代理对象 * method: 目标对象的方法对象 * args: 目标对象方法的参数 * return: 目标对象方法的返回值 */ public Object invoke(Object proxy, Method method, Object[] args) throws Throwable { System.out.println("before"); Object retValue = method.invoke(target, args); System.out.println("after"); return retValue; } }); Hello proxy = (Hello) proxyInstance; proxy.say("LYX"); //可以把InvocationHandler提取出来，单独写一个类，为了方便大家看，这里我用内部类的形式 class JDKProxy implements InvocationHandler { private Object target; public JDKProxy(Object target){ this.target = target; } public Object invoke(Object proxy, Method method, Object[] args) throws Throwable { before(); Object result = method.invoke(target, args); after(); return result; } private void before(){ System.out.println("Before"); } private void after(){ System.out.println("After"); } } InvocationHandler ih = new JDKProxy(target); Object proxyInstance2 = Proxy.newProxyInstance(target.getClass().getClassLoader(), target.getClass().getInterfaces(), ih); Hello proxy2 = (Hello) proxyInstance2; proxy2.say("LZHL"); }}

2》CGLib动态代理(基于目标类，通过继承目标类，从而保证功能一致)，需要导入cglib-3.2.4.jar包

pom.xml

<dependencies> <!-- https://mvnrepository.com/artifact/cglib/cglib --> <dependency> <groupId>cglib</groupId> <artifactId>cglib</artifactId> <version>3.2.4</version> </dependency></dependencies>

1)目标类

public class Hi { public void sayHi(String msg){ System.out.println("Hi,"+msg); }}

2)测试

/** * @Author LZHL * @Create 2017-02-19 13:19 * @Description */public class Main { public static void main(String[] args) { Enhancer enhancer = new Enhancer(); //设置父类 enhancer.setSuperclass(Hi.class); //设置回调函数 enhancer.setCallback(new MethodInterceptor() { public Object intercept(Object target, Method method, Object[] args, MethodProxy methodProxy) throws Throwable { System.out.println("before"); Object retValue = methodProxy.invokeSuper(target, args); System.out.println("after"); return retValue; } }); Object proxy = enhancer.create(); Hi hi = (Hi) proxy; hi.sayHi("LXY"); //可以把MethodInterceptor提取出来，单独写一个类，为了方便大家看，这里我用内部类的形式 class CGLibProxy implements MethodInterceptor { public <T> T getProxy(Class<T> clazz){ return (T) Enhancer.create(clazz, this); } public Object intercept(Object target, Method method, Object[] args, MethodProxy proxy) throws Throwable { before(); Object result = proxy.invokeSuper(target, args); after(); return result; } private void before(){ System.out.println("Before"); } private void after(){ System.out.println("After"); } } CGLibProxy cgLibProxy = new CGLibProxy(); Hi hi2 = cgLibProxy.getProxy(Hi.class); hi2.sayHi("LZHL"); }}

以上所述是小编给大家介绍的Java静态代理和动态代理总结，希望对大家有所帮助，如果大家有任何疑问欢迎给我留言，小编会及时回复大家的！