cglib动态代理

Posted 2021-12-29 linchongatfirst

cglib动态代理相比于JDK动态代理的的优秀之处在于它是够实现非接口的动态代理，且提供了多种回调方式，这里就将callbackFilter和MethodInterceptor两种

被代理类

package com.yangpeng.proxy;

public class BookPorxyImpl 
    public void addBook() 
        System.out.println("增加图书的普通放方法");
    
    public void addBall() 
        System.out.println("增加Ball的普通放方法");
    

 

 

提供统一的回调方式，cglib的主要回调是MethodInterceptor接口，和用于创建动态代理的Enhancer类

package com.yangpeng.proxy;

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 BookProxyLib implements MethodInterceptor
    private Object target;
//这一个方法你也可以不写在这里，这里只是采用Enhancer对传入的原对象做一个包装，返回一个代理类
    public Object getInstance(Object target) 
        this.target = target;
        Enhancer enhancer = new Enhancer();
        enhancer.setSuperclass(this.target.getClass());
        enhancer.setCallback(this);
        return enhancer.create();
    
   //接口实现
    public Object intercept(Object obj, Method method, Object[] args, MethodProxy proxy) throws Throwable 
        System.out.println("事务开始");
        proxy.invokeSuper(obj, args);
        System.out.println("事务结束");
        return null;
    
    

 

另外一种回调：

package com.yangpeng.proxy;

import java.lang.reflect.Method;

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

public class BookProxyLib2 implements MethodInterceptor

    public Object intercept(Object obj, Method method, Object[] args, MethodProxy proxy) throws Throwable 
        System.out.println("不错哦!");
        return null;
    

 

CallbackFilter：

package com.yangpeng.proxy;

import java.lang.reflect.Method;

import com.sun.xml.internal.ws.api.message.AttachmentEx.MimeHeader;

import net.sf.cglib.proxy.CallbackFilter;

public class BookCallBackFilter implements CallbackFilter 

    /**
     * 方法返回的值时和callback回调接口返回的数组一一对应的数组下标
     */
    public int accept(Method method) 
        String name =method.getName();
        if("addBook".equals(name)) 
            return 0;
        
        return 1;
    

 

测试：

 

import com.sun.org.apache.bcel.internal.generic.NEW;

import net.sf.cglib.proxy.Callback;
import net.sf.cglib.proxy.Enhancer;
import net.sf.cglib.proxy.NoOp;

public class TestLib 
    public static void main(String[] args) 
    
        proxy();
        callbackProxy();
    
    


    public static void proxy() 
        System.out.println("---------------统一采用MethodInterceptor，所有的业务都经过同一个intercept调用---------");
        BookProxyLib cglib = new BookProxyLib();
        BookPorxyImpl bookcglib = (BookPorxyImpl) cglib.getInstance(new BookPorxyImpl());
        bookcglib.addBook();
        bookcglib.addBall();
        System.out.println("-------------------------------------------------------------------------------");
    
//callback Proxy
    public  static  void callbackProxy() 
        System.out.println("----------------采用callbackFilter对不同方法实现不同代理逻辑------------------------------");
        BookPorxyImpl bookImpl = new BookPorxyImpl();
        Enhancer enhancer = new Enhancer();
//        设置代理目标
        enhancer.setSuperclass(bookImpl.getClass());
//这里声明一个Callback数组，此处对bookProxyImpl的两个方法分别做使用了两个回调，
       Callback[] callbacks = new Callback[] new BookProxyLib(),new BookProxyLib2(),NoOp.INSTANCE ;
        enhancer.setCallbacks(callbacks);
        enhancer.setCallbackFilter(new BookCallBackFilter());
        
        BookPorxyImpl impl = (BookPorxyImpl) enhancer.create();
        impl.addBall();
        impl.addBook();