动态代理使用

落日映苍穹つ 2022-08-05 08:48 128阅读 0赞

## 动态代理使用 ##

java动态代理机制以巧妙的方式实现了代理模式的设计理念。![动态代理类图][javaproxyclass.jpg]

代理模式示例代码

![复制代码][copycode.gif]

public interface Subject   
    {   
      public void doSomething();   
    }   
    public class RealSubject implements Subject   
    {   
      public void doSomething()   
      {   
        System.out.println( "call doSomething()" );   
      }   
    }   
    public class ProxyHandler implements InvocationHandler   
    {   
      private Object proxied;   
         
      public ProxyHandler( Object proxied )   
      {   
        this.proxied = proxied;   
      }   
         
      public Object invoke( Object proxy, Method method, Object[] args ) throws Throwable   
      {   
        //在转调具体目标对象之前，可以执行一些功能处理
    
        //转调具体目标对象的方法
        return method.invoke( proxied, args);  
        
        //在转调具体目标对象之后，可以执行一些功能处理
      }    
    }

![复制代码][copycode.gif]

import java.lang.reflect.InvocationHandler;   
    import java.lang.reflect.Method;   
    import java.lang.reflect.Proxy;   
    import sun.misc.ProxyGenerator;   
    import java.io.*;   
    public class DynamicProxy   
    {   
      public static void main( String args[] )   
      {   
        RealSubject real = new RealSubject();   
        Subject proxySubject = (Subject)Proxy.newProxyInstance(Subject.class.getClassLoader(), 
         new Class[]{Subject.class}, 
         new ProxyHandler(real));
             
        proxySubject.doSomething();
       
        //write proxySubject class binary data to file   
        createProxyClassFile();   
      }   
         
      public static void createProxyClassFile()   
      {   
        String name = "ProxySubject";   
        byte[] data = ProxyGenerator.generateProxyClass( name, new Class[] { Subject.class } );   
        try  
        {   
          FileOutputStream out = new FileOutputStream( name + ".class" );   
          out.write( data );   
          out.close();   
        }   
        catch( Exception e )   
        {   
          e.printStackTrace();   
        }   
      }   
    }

![复制代码][copycode.gif]

[javaproxyclass.jpg]: http://www.flyoung.me/assets/images/javaproxyclass.jpg
[copycode.gif]: /images/20220731/6e09c06a60d14069829529d0bd2af43c.png