java代理（proxy）

静态代理

public class StaticProxy implements Man {
    private Man man;

    public StaticProxy() {
        man = new ManImpl();
    }

    @Override
    public void look(String bookName) {
        before();
        man.look(bookName);
        after();
    }

    private void before(){
        System.out.println("before");
    }

    private void after(){
        System.out.println("after");
    }

    public static void main(String[] args){
        Man man = new StaticProxy();
        man.look("静态代理");
    }
}

JDK 动态代理

import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;

/**
 * Created by on 2017/12/9.
 * JDK 动态代理
 */
public class DynamicProxy implements InvocationHandler {
    private Object target;

    public DynamicProxy(Object target) {
        this.target = target;
    }

    public <T> T getProxy(){
        return (T) Proxy.newProxyInstance(target.getClass().getClassLoader(),target.getClass().getInterfaces(),this);
    }

    @Override
    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");
    }

    public static void main(String[] args){
        DynamicProxy dynamicProxy = new DynamicProxy(new ManImpl());
        Man man = dynamicProxy.getProxy();
        man.look("JDK 动态代理");
    }
}

CGLib 动态代理
1）引入maven依赖

<!-- CGLibproxy代理 -->
        <dependency>
            <groupId>cglib</groupId>
            <artifactId>cglib</artifactId>
            <version>3.1</version>
        </dependency>

2）代码实现

import net.sf.cglib.proxy.Enhancer;
import net.sf.cglib.proxy.MethodInterceptor;
import net.sf.cglib.proxy.MethodProxy;

import java.lang.reflect.Method;

/**
 * Created by on 2017/12/9.
 * CGLib 动态代理
 */
public class CGLibProxy implements MethodInterceptor {
    public <T> T getProxy(Class<T> cls){
        return (T) Enhancer.create(cls,this);
    }

    @Override
    public Object intercept(Object o, Method method, Object[] objects, MethodProxy methodProxy) throws Throwable {
        before();
        Object result = methodProxy.invokeSuper(o,objects);
        after();
        return result;
    }

    private void before(){
        System.out.println("before");
    }

    private void after(){
        System.out.println("after");
    }

    public static void main(String[] args){
        CGLibProxy cgLibproxy = new CGLibProxy();
        Man man = cgLibproxy.getProxy(ManImpl.class);
        man.look("CGLib 动态代理");
    }
}