求教一个简单的文件上传问题 表示困扰很久了

最近在做一个企业级java的上机实验

实现文件的上传

期间遇到了一个问题，也不知道是哪儿出错了 麻烦大神们给指点指点

xml代码

 <servlet>

    <description>This is the description of my J2EE component</description>

    <display-name>This is the display name of my J2EE component</display-name>

    <servlet-name>fileupload</servlet-name>

    <servlet-class>com.cugb.java.fileupload</servlet-class>

  </servlet>



  <servlet-mapping>

    <servlet-name>fileupload</servlet-name>

    <url-pattern>/fileupload</url-pattern>

  </servlet-mapping>

  <welcome-file-list>

    <welcome-file>index.jsp</welcome-file>

  </welcome-file-list>

然后是index.jsp里的代码

<%@ page language="java" import="java.util.*" pageEncoding="gbk"%>

<%

String path = request.getContextPath();

String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";

%>



<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">

<html>

  <head>

    <base href="<%=basePath%>">

    

    <title>My JSP 'index.jsp' starting page</title>

	<meta http-equiv="pragma" content="no-cache">

	<meta http-equiv="cache-control" content="no-cache">

	<meta http-equiv="expires" content="0">    

	<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">

	<meta http-equiv="description" content="This is my page">

	<!--

	<link rel="stylesheet" type="text/css" href="styles.css">

	-->

  </head>

  

  <body>

  

   <form action="fileupload" method="post" enctype="Multipart/form-data">

    username：<input type="text" name="usename"> <br/>  

   Choose a file:

   <input type="file" name="file1"><br>

   <input type="submit" value="submit">

   

   

   

   </form>

  </body>

</html>

Servlet里的代码 fileupload.java'

public void doPost(HttpServletRequest request, HttpServletResponse response)

			throws ServletException, IOException {



		DiskFileItemFactory dfu =new DiskFileItemFactory();

		

		String path=request.getRealPath("/upload");

		dfu.setRepository(new File(path));

		

		dfu.setSizeThreshold(1024*1024);

		

		ServletFileUpload upload=new ServletFileUpload(dfu);

		

		try{

			List<FileItem> list=(List<FileItem>)upload.parseRequest(request);

			for(FileItem item : list)  

			{

				String name=item.getFieldName();

				if(!item.isFormField());

				{

					String value=item.getName();

					int start=value.lastIndexOf("\\");

					

					String filename=value.substring(start+1);

					

					request.setAttribute(name, filename);

					item.write( new File(path,filename) );

				}

			}

		} catch (FileUploadException e) {  

            // TODO Auto-generated catch block  

            e.printStackTrace();  

        } 

		 catch (Exception e) {  

	            // TODO Auto-generated catch block  

	              

	            //e.printStackTrace();  

	        }

		 request.getRequestDispatcher("index.jsp").forward(request, response);  

	}

发布到tomcat上都是没问题的 就是点击提交的时候 报错 我也不知道是哪儿错了

exception 



javax.servlet.ServletException: Servlet execution threw an exception





root cause 



java.lang.NoClassDefFoundError: org/apache/commons/io/output/DeferredFileOutputStream

	org.apache.commons.fileupload.disk.DiskFileItemFactory.createItem(DiskFileItemFactory.java:191)

	org.apache.commons.fileupload.FileUploadBase.parseRequest(FileUploadBase.java:350)

	org.apache.commons.fileupload.servlet.ServletFileUpload.parseRequest(ServletFileUpload.java:126)

	com.cugb.java.fileupload.doPost(fileupload.java:88)

	javax.servlet.http.HttpServlet.service(HttpServlet.java:710)

	javax.servlet.http.HttpServlet.service(HttpServlet.java:803)





root cause 



java.lang.ClassNotFoundException: org.apache.commons.io.output.DeferredFileOutputStream

	org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1358)

	org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1204)

	java.lang.ClassLoader.loadClassInternal(ClassLoader.java:320)

	org.apache.commons.fileupload.disk.DiskFileItemFactory.createItem(DiskFileItemFactory.java:191)

	org.apache.commons.fileupload.FileUploadBase.parseRequest(FileUploadBase.java:350)

	org.apache.commons.fileupload.servlet.ServletFileUpload.parseRequest(ServletFileUpload.java:126)

	com.cugb.java.fileupload.doPost(fileupload.java:88)

	javax.servlet.http.HttpServlet.service(HttpServlet.java:710)

	javax.servlet.http.HttpServlet.service(HttpServlet.java:803)





note The full stack trace of the root cause is available in the Apache Tomcat/6.0.13 logs.

希望各位热心的大神给看看 困扰很久了