Java反射(JDK)与动态代理(CGLIB)详解

import java.lang.reflect.InvocationHandler;

import java.lang.reflect.Method;

import java.lang.reflect.Proxy;

// 定义一个接口

interface MyInterface {

     void fun();

}

// 用一个类去实现这个接口

class Person implements MyInterface {

     @Override

     public void fun() {

         System.out.println( "Person实现接口方法" );

     }

}

// 用一个类实现InvocationHandler接口

class MyInvocationHandler<T> implements InvocationHandler {

     //InvocationHandler持有的被代理对象

     T target;

     public MyInvocationHandler(T target) {

         this .target = target;

     }

     /**

      * proxy:代表动态代理对象

      * method：代表正在执行的方法

      * args：代表调用目标方法时传入的实参

      */

     @Override

     public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {

         System.out.println( "代理执行" + method.getName() + "方法" ); // 在原方法的基础上添加其他逻辑

         Object result = method.invoke(target, args); // 通过invoke方法调用原方法

         return result;

     }

}

public class Main {

     public static void main(String[] args) {

         Person person = new Person();

         InvocationHandler invocationHandler = new MyInvocationHandler<>(person);

         MyInterface proxy = (MyInterface) Proxy.newProxyInstance(Person. class .getClassLoader(),

                 Person. class .getInterfaces(), invocationHandler);

         proxy.fun();

     }

}

public class Main {

     public static void main(String[] args) {

         Enhancer enhancer = new Enhancer();

         enhancer.setSuperclass(Car. class );

         enhancer.setCallback( new MethodInterceptor() {

             @Override

             public Object intercept(Object obj, Method method, Object[] args, MethodProxy methodProxy)

                     throws Throwable {

                 System.out.println( "before" );

                 Object res = methodProxy.invokeSuper(obj, args);

                 System.out.println( "after" );

                 return res;

             }

         });

         Car car = (Car) enhancer.create();

         car.print();

     }

}

class Car {

     void print() {

         System.out.println( "执行原方法" );

     }

}

< dependency >

     < groupId >org.sonatype.sisu.inject</ groupId >

     < artifactId >cglib</ artifactId >

     < version >3.1.1</ version >

</ dependency >