The difference between Proxy and CGLIB

最新推荐文章于 2023-10-22 00:15:00 发布

原创最新推荐文章于 2023-10-22 00:15:00 发布 · 785 阅读

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文章标签：

#object #interceptor #class #import #string #jdk

本文介绍JAVA中使用JDK Proxy和CGLIB实现动态代理的方法，包括定义接口与类、设置回调类、创建动态代理工厂及单元测试等步骤。

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JAVA实现动态代理常用的有两种方式：

1， java.lang.reflect.Proxy (JDK)

2， net.sf.cglib.proxy.Enhancer（cglib）

两者之间的区别如图1-1 所示。

图1-1 jdk 和 cglib 概要图

jdk和cglib实现动态代理的原理是完全不同的，jdk是通过目标class所实现的接口，而cglib是通过目标对象的子类完成的。

他们二者互相补充，基本上能够满足所有的动态代理需求。

jdk和cglib实现动态代理的简单例子如下所示：

jdk：

****************************************************************************************************

1，定义接口

public interface SubInter {

   public abstract void display() ;

   public abstract void display2();

}

2，定义实现类

public class SonObject implements SubInter {

   @Override
   public void display() {
       System.out.println("This is a realy object !");
   }

   @Override
   public void display2() {
       System.out.println("This is a test2!");

   }

}

3，设置回调类

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

public class Dynamic implements InvocationHandler {

   private Object object;

   private String validateString;

   public Dynamic(Object object, String validateString) {
       this.object = object;
       this.validateString = validateString;
   }

   @Override
   public Object invoke(Object arg0, Method arg1, Object[] arg2)
           throws Throwable {
       boolean b = validateMehod(arg1.getName());
       Object object = null;
       if (b) {
           before();
           object = arg1.invoke(this.object, arg2);
           after();
       }else {
           object = arg1.invoke(this.object, arg2);
       }
       return object;
   }

   public boolean validateMehod(String methodName) {
       boolean b = false;
       String methodNames[] = validateString.split("&");
       for (String name : methodNames) {
           if (methodName.contains(name)) {
               b = true;
               return b;
           }
       }
       return b;
   }

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

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

}

4，动态代理工厂

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

/**
*
* @author gyf
*
*         We can get a proxy instance for the target object by the specify
*         InvocationHandler.
*
*/
public class DynamicProxyFactory {

   public static Object createProxyInstance(Object targetObject,
           InvocationHandler handler) {
       return Proxy.newProxyInstance(targetObject.getClass().getClassLoader(),
               targetObject.getClass().getInterfaces(), handler);
   }

}

5，单元测试

public class Junit {

   @Test
   public void testJDK() {
       SubInter targetObject = new SonObject();
       InvocationHandler handler = new Dynamic(targetObject, "2&3");
       SubInter object = (SubInter)DynamicProxyFactory.createProxyInstance(targetObject, handler);
       object.display2();
   }

}

cglib

*************************************************************************************************

1，定义目标类

public class TargetObject {

   public void display() {
       System.out.println("This is a test");
   }

   public void display2() {
       System.out.println("This is a test2");
   }

}

2，定义回调类

import java.lang.reflect.Method;

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

public class CglibDynamic implements MethodInterceptor{

   private Object targetObject;

   public CglibDynamic(){}

   public CglibDynamic(Object object) {
       this.targetObject = object;
   }

   @Override
   public Object intercept(Object arg0, Method arg1, Object[] arg2,
           MethodProxy arg3) throws Throwable {

       Object object = arg3.invoke(targetObject, arg2);

       return object;
   }

}

3，定义动态代理工厂

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

public class CglibDynamicFactory {

   public static Object getProxyInstance(Object targetObject,
           MethodInterceptor methodInterceptor) {

       Enhancer enhancer = new Enhancer();
       enhancer.setSuperclass(targetObject.getClass());
       enhancer.setCallback(methodInterceptor);

       return enhancer.create();
   }

}

4，单元测试

import net.sf.cglib.proxy.MethodInterceptor;

import org.junit.Test;

import com.cglib.proxy.CglibDynamic;
import com.cglib.proxy.CglibDynamicFactory;
import com.cglib.proxy.TargetObject;

public class Junit {

   @Test
   public void testCglib() {
       TargetObject object = new TargetObject();
       MethodInterceptor interceptor = new CglibDynamic(object);

       TargetObject son = (TargetObject)CglibDynamicFactory.getProxyInstance(object, interceptor);
       son.display();
   }

}