retryproxy.java

《精通RMI：Java与EJB企业级应用开发》书籍的源代码. 本书是讲述RMI技术的经典著作

/*
 * Copyright 1999 by dreamBean Software,
 * All rights reserved.
 */
package smartproxy.proxies;

import java.lang.reflect.Proxy;
import java.lang.reflect.Method;
import java.lang.reflect.InvocationHandler;
import java.lang.reflect.InvocationTargetException;
import java.rmi.Remote;
import java.rmi.RemoteException;
import java.rmi.ServerException;
import java.rmi.Naming;

/**
 *    This is a smart proxy wrapper that retries calls
 *     
 *    Note that it is not tightly bound to the remote object interface,
 *    and can therefore be reused with any remote object(!)
 *
 *   @author Rickard 謆erg ([e-mail])
 *   @version $Revision:$
 */
public class RetryProxy
   implements InvocationHandler, java.io.Serializable, LinkedProxy
{
   Object next;
   int retryCount;
   long sleepTime;

   // Constructors --------------------------------------------------
   public RetryProxy(Object next)
   {
      this(next, 10, 3000); // Retry for 30 seconds
   }
   
   public RetryProxy(Object next, int retryCount,long sleepTime)
   {
      this.next = next;
      this.retryCount = retryCount;
      this.sleepTime = sleepTime;
   }
   
   // Public --------------------------------------------------------
   public Object invoke(Object proxy,
                        Method method,
                        Object[] args)
      throws Throwable
   {
      RemoteException ex = null;
      for (int i = 0; i < retryCount; i++)
      {
         try
         {
            return method.invoke(next, args);
         } catch (InvocationTargetException e)
         {
            try
            {
               throw e.getTargetException();
            } catch (java.rmi.ConnectException exc)
            {
               ex = exc;
               Thread.sleep(sleepTime);
            } catch (java.rmi.ConnectIOException exc)
            {
               ex = exc;
               Thread.sleep(sleepTime);
            }
         }
         //Retry
      }
      
      // Retry failed
      throw ex;
   }
   
   public Object getNext()
   {
      return next;
   }
   
   public void setNext(Object next)
   {
      this.next = next;
   }
}