java-动态代理

package com.amigo.study.DynamicProxyDemo;

/**
 * Created by moi on 2017/10/1.
 */
public interface IDbService {
    public String getDBName();

}

package com.amigo.study.DynamicProxyDemo;

/**
 * Created by moi on 2017/10/1.
 */
public class DBServiceImpl implements IDbService {

    @Override
    public String getDBName() {
        System.out.println("db name is amigo.");
        return "amigo";
    }
}

package com.amigo.study.DynamicProxyDemo;

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

/**
 * Created by moi on 2017/10/1.
 */
public class DBServiceInvokeHandler implements InvocationHandler {
    private Object target;

    DBServiceInvokeHandler() {
        super();
    }

    DBServiceInvokeHandler(Object target) {
        super();
        this.target = target;
    }
　　

      /**
      * 动态代理的目的往往是要增强被代理类，这里就是增强逻辑的放置位置。
      * @param proxy
      * @param method
      * @param args
      * @return
      * @throws Throwable
      */

    @Override
    public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
        if ("getDBName".equals(method.getName())) {
            System.out.println("++++++before " + method.getName() + "++++++");
            Object result = method.invoke(target, args);
            System.out.println("++++++after " + method.getName() + "++++++");
            return result;
        } else {
            Object result = method.invoke(target, args);
            return result;
        }
    }
}

package com.amigo.study.DynamicProxyDemo;

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

/**
 * Created by moi on 2017/10/1.
 */
public class DynamicProxyTest {
    public static void main(String[] args) {
        // 这里是保存下来生成的.class文件。 注意：要在工程根目录新建/com/sun/proxy的目录，要不会报错。
        System.getProperties().put("sun.misc.ProxyGenerator.saveGeneratedFiles", "true");
        JDKDynamicProxyTest();
    }

    public static void JDKDynamicProxyTest() {
        IDbService iDbService = new DBServiceImpl();
        InvocationHandler invocationHandler = new DBServiceInvokeHandler(iDbService);
        IDbService userServiceProxy = (IDbService) Proxy.newProxyInstance(iDbService.getClass().getClassLoader(),
                iDbService.getClass().getInterfaces(), invocationHandler);
        System.out.println(userServiceProxy.getDBName());
    }
}

package com.amigo.study.DynamicProxyDemo;

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

import java.lang.reflect.Method;

/**
 * Created by moi on 2017/10/1.
 */
public class DBServiceMethodInterceptor implements MethodInterceptor {

    @Override
    public Object intercept(Object o, Method method, Object[] objects, MethodProxy methodProxy) throws Throwable {
        System.out.println("Before:" + method);
        Object object = methodProxy.invokeSuper(o, objects);
        System.out.println("After:" + method);
        return object;
    }
}

package com.amigo.study.DynamicProxyDemo;

import net.sf.cglib.proxy.Enhancer;

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

/**
 * Created by moi on 2017/10/1.
 */
public class DynamicProxyTest {
    public static void main(String[] args) {
        //        JDKDynamicProxyTest();
        CglibDynamicProxyTest();
    }

    public static void JDKDynamicProxyTest() {
        IDbService iDbService = new DBServiceImpl();
        InvocationHandler invocationHandler = new DBServiceInvokeHandler(iDbService);
        IDbService userServiceProxy = (IDbService) Proxy.newProxyInstance(iDbService.getClass().getClassLoader(),
                iDbService.getClass().getInterfaces(), invocationHandler);
        System.out.println(userServiceProxy.getDBName());
    }

    public static void CglibDynamicProxyTest(){
        Enhancer enhancer = new Enhancer();
　　　　 // 设置被代理类
        enhancer.setSuperclass(DBServiceImpl.class);
　　　　  // 回调函数用于增强被代理类
        enhancer.setCallback(new DBServiceMethodInterceptor());
        DBServiceImpl dbService = (DBServiceImpl)enhancer.create();
        dbService.getDBName();
    }
}