静态代理

在不破坏原有功能的情况下，进行升级改造。
使用场景，通常在旧项目改造和升级中，不能或者没有条件在源码的基础上升级和改造
所以用代理模式是一个不错的选择。

功能列表（接口）

public interface IDoing {public String doFirst();public void doSecond();
}

原有功能，功能的实现

@Slf4j
public class DoingImpl implements IDoing {@Overridepublic String doFirst() {String me = "Hi there,this is Michael";return me;}@Overridepublic void doSecond() {log.info("let's started now");}
}

在不破坏原功能的情况下Enhance

public class DoingProxy implements IDoing {private IDoing idoing;DoingProxy(){this.idoing = new DoingImpl();}@Overridepublic String doFirst() {return idoing.doFirst().toUpperCase();}@Overridepublic void doSecond() {idoing.doSecond();}
}

Test

@Slf4j
public class TestProxy {public static void main(String[] args) {IDoing idoing = new DoingImpl();IDoing idoing = new DoingProxy();log.info(idoing.doFirst());idoing.doSecond();}
}

Hi there,this is Michael
HI THERE,THIS IS MICHAEL
let’s started now

JDK 动态代理

在静态代理的基础上改造

@Slf4j
public class TestProxy {public static void main(String[] args) {IDoing target = new DoingImpl();IDoing proxyIdoing = (IDoing) Proxy.newProxyInstance(target.getClass().getClassLoader(), target.getClass().getInterfaces(),new InvocationHandler() {@Overridepublic Object invoke(Object proxy, Method method, Object[] args) throws Throwable {Object result = method.invoke(target, args);if (result!=null) {result = result.toString().toUpperCase();}return result;}} );String doFirst = proxyIdoing.doFirst();log.info(doFirst);proxyIdoing.doSecond();}
}

Cglib 代理模式

Callback的MethodInterceptor

public interface MethodInterceptor extends Callback

public class CglibProxyEnhancer implements MethodInterceptor {public DoingImpl getCglibCreator() {Enhancer enhancer = new Enhancer();enhancer.setSuperclass(DoingImpl.class);enhancer.setCallback(this);return (DoingImpl) enhancer.create();}@Overridepublic Object intercept(Object obj, Method method, Object[] args,MethodProxy proxy) throws Throwable {Object result = method.invoke(new DoingImpl(), args);if (result!=null) {result = result.toString().toUpperCase();}return result;}
}

test

@Slf4j
public class TestProxy {public static void main(String[] args) {CglibProxyEnhancer cglibProxyEnhancer = new CglibProxyEnhancer();DoingImpl proxyIdoing = cglibProxyEnhancer.getCglibCreator();String doFirst = proxyIdoing.doFirst();log.info(doFirst);proxyIdoing.doSecond();}
}