apache fileupload 组件问题 在线等 急！！！

####  servlet:UploadImage.java #######package com.nic;
import javax.servlet.*;
import javax.servlet.http.*;
import java.io.*;
import java.util.*;
import java.util.regex.*;
import org.apache.commons.fileupload.*;public class UploadImage extends HttpServlet {
private static final String CONTENT_TYPE = "text/html;   charset=GB2312"; // Process the HTTP Post request
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
//PrintWriter out = response.getWriter();
try   {   
      String   file_name;   
      DiskFileUpload   upload   =   new   DiskFileUpload();   
      List   items   =   upload.parseRequest(request);   
      upload.setSizeMax(3*102400);   
      //maximum   size   that   will   be   stored   in   memory?   
      //   设置最多只允许在内存中存储的数据,单位:字节   
      //upload.setSizeThreshold(4096);   
      //   设置一旦文件大小超过getSizeThreshold()的值时数据存放在硬盘的目录   
      upload.setRepositoryPath("d:\\temp");   
      //开始读取上传信息   
    
      Iterator   iter   =   items.iterator();   
      FileItem   item;   
      while   (iter.hasNext())   {   
      item   =   (FileItem)   iter.next();   
      if   (item.isFormField())   {   
      //   
      }   else   {   
      //取文件本地路径加文件名   
      String   itemName   =   item.getName();   
      file_name   =   itemName.substring(itemName.lastIndexOf("\\")+1);   
      file_name   =   "D:\\"   +   file_name;   
    
     // out.println(file_name);   
    
      File   newFile   =   new   File(file_name);   
      if   (newFile.exists())   {   
                                      //   
      }   
      else   {   
                                            newFile.createNewFile();   
                                          item.write(newFile);   
      }   
      }   
      }   
  }   catch   (Exception   e)   {   
      System.out.println("上传出错:"+e);   
  }  }
}##### upload.html #####<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title here</title>
</head>
<body>
<h1>文件上传演示</h1><form name="uploadform" method="POST" action="Test1" enctype="multipart/form-data"><table border="1" width="450" cellpadding="4" cellspacing="2"
bordercolor="#9BD7FF"> <tr>
<td width="100%" colspan="2">文件1：<input name="x" size="40"
type="file"></td>
</tr> <tr>
<td width="100%" colspan="2">文件2：<input name="y" size="40"
type="file"></td>
</tr> <tr>
<td width="100%" colspan="2">文件3：<input name="z" size="40"
type="file"></td>
</tr></table><br />
<br /><table> <tr>
<td align="center"><input name="upload" type="submit"
value="开始上传" /></td>
</tr></table></form></body>
</html>
##### 错误提示：####java.lang.NoClassDefFoundError: org/apache/commons/io/output/DeferredFileOutputStream
org.apache.commons.fileupload.DefaultFileItemFactory.createItem(DefaultFileItemFactory.java:103)
org.apache.commons.fileupload.FileUploadBase.parseRequest(FileUploadBase.java:350)
org.apache.commons.fileupload.FileUploadBase.parseRequest(FileUploadBase.java:302)
com.nic.UploadImage.doPost(UploadImage.java:19)
javax.servlet.http.HttpServlet.service(HttpServlet.java:709)
javax.servlet.http.HttpServlet.service(HttpServlet.java:802)