静态代理

public class ProxyDemo {    public static void main(String[] args) {        RealImage realImage = new RealImage();        ProxyImage proxyImage = new ProxyImage(realImage);        proxyImage.doSomething();    }}interface Image {    void doSomething();}class RealImage implements Image {    @Override    public void doSomething() {        System.out.println("Real image");    }}class ProxyImage implements Image {    private RealImage realImage;    public ProxyImage(RealImage realImage) {        this.realImage = realImage;    }    @Override    public void doSomething() {        System.out.println("proxy start");        realImage.doSomething();        System.out.println("proxy end");    }}

 

打印结果：

proxy startReal imageproxy end

 

JDK 动态代理（基于接口）

import java.lang.reflect.InvocationHandler;import java.lang.reflect.Method;import java.lang.reflect.Proxy;public class ProxyDemo {    public static void main(String[] args) {        Target target = new TargetImpl();        TargetIH targetIH = new TargetIH(target);        Class
      clazz = target.getClass();        Target proxyInstance = (Target) Proxy.newProxyInstance(clazz.getClassLoader(), clazz.getInterfaces(), targetIH);        proxyInstance.doSomething();        proxyInstance.doSomethingElse();    }}interface Target {    void doSomething();    void doSomethingElse();}class TargetImpl implements Target {    @Override    public void doSomething() {        System.out.println("TargetImpl doSomething");    }        @Override    public void doSomethingElse() {        System.out.println("TargetImpl doSomethingElse");    }}class TargetIH implements InvocationHandler {    private Object target;    public TargetIH(Object target) {        this.target = target;    }    @Override    public Object invoke(Object proxy, Method method, Object[] args) {        System.out.println("proxy start");        Object result = null;        try {            result = method.invoke(target, args);        } catch (Exception e) {            // do something        }        System.out.println("proxy end");        return result;    }}

 

打印：

proxy startTargetImpl doSomethingproxy endproxy startTargetImpl doSomethingElseproxy end

 

CGLIB

 （Byte Code Generation Library is high level API to generate and transform Java byte code. It is used by AOP, testing, data access frameworks to generate dynamic proxy objects and intercept field access）动态代理，不需要有接口

         
      
       cglib
          
      
       cglib
          
      
       3.2.5
      
     

 

import java.lang.reflect.Method;import net.sf.cglib.proxy.Enhancer;import net.sf.cglib.proxy.MethodInterceptor;import net.sf.cglib.proxy.MethodProxy;public class ProxyDemo {    public static void main(String[] args) {                TargetMI interceptor = new TargetMI();        Enhancer e = new Enhancer();        e.setSuperclass(Target.class);        e.setCallback(interceptor);        Target proxyInstance = (Target) e.create();        proxyInstance.doSomething();    }}class Target {    public void doSomething() {        System.out.println("doSomething");    }}class TargetMI implements MethodInterceptor {    @Override    public Object intercept(Object obj, Method method, Object[] args, MethodProxy proxy) throws Throwable {        System.out.println("proxy start");        Object retValFromSuper = proxy.invokeSuper(obj, args);        System.out.println("proxy end");        return retValFromSuper;    }}

打印：

proxy startdoSomethingproxy end

 

Spring AOP

         
              
       
        org.springframework
               
       
        spring-context
               
       
        4.3.3.RELEASE
           
          
              
       
        org.aspectj
               
       
        aspectjweaver
               
       
        1.8.10
           
      
     

package cn.zno.foo;import org.aspectj.lang.JoinPoint;import org.aspectj.lang.annotation.After;import org.aspectj.lang.annotation.Aspect;import org.aspectj.lang.annotation.Before;import org.aspectj.lang.annotation.Pointcut;import org.springframework.context.ApplicationContext;import org.springframework.context.support.ClassPathXmlApplicationContext;import org.springframework.stereotype.Component;public class ProxyDemo {    public static void main(String[] args) {        @SuppressWarnings("resource")        ApplicationContext ctx = new ClassPathXmlApplicationContext("beans.xml");        Target target = (Target) ctx.getBean(Target.class);        target.doSomething();        target.doSomethingElse();    }}interface Target {    public void doSomething();    public void doSomethingElse();}@Componentclass TargetImpl implements Target {    @Override    public void doSomething() {        System.out.println("doSomething");    }    @Override    public void doSomethingElse() {        System.out.println("doSomethingElse");    }}@Component // 需要注册到bean工厂，否则不会生效@Aspect // 需要配置Spring AOPclass TargetInterceptor {        @Pointcut("execution(* doSomething(..)) || execution(* doSomethingElse(..))") // the pointcut(target method) signature    private void anysdf() {        System.out.println("pointcut signature");    }    @Before(value = "anysdf()")    public void before(JoinPoint joinPoint) {        System.out.println("Before");    }    @After("anysdf()")    public void after() {        System.out.println("After");    }}

打印：

BeforedoSomethingAfterBeforedoSomethingElseAfter