，为什么这个FLEX和SERVLET上传图片总是出错！

<?xml version="1.0" encoding="utf-8"?>
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml" layout="absolute" xmlns="*" creationComplete="init();">
<mx:Script>
<![CDATA[
import flash.net.FileReference;
import mx.controls.Alert;
import mx.events.CloseEvent;
import flash.events.*;

private var file: FileReference;

private function init(): void{
Security.allowDomain("*");
file = new FileReference();
file.addEventListener(ProgressEvent.PROGRESS, onProgress);
file.addEventListener(Event.SELECT, onSelect);
}

private function upload(): void{
var imageTypes:FileFilter = new FileFilter("Images (*.jpg, *.jpeg, *.png)", "*.jpg;*.jpeg;*.png");
var allTypes:Array = new Array(imageTypes);
file.browse(allTypes);
file.browse();
}

private function onSelect(e: Event): void{
Alert.show("上传 " + file.name + " (共 "+Math.round(file.size)+" 字节)?",
"确认上传",
Alert.YES|Alert.NO,
null,
proceedWithUpload);
}

private function onProgress(e: ProgressEvent): void{
lbProgress.text = " 已上传 " + e.bytesLoaded 
+ " 字节，共 " + e.bytesTotal + " 字节";
var proc: uint = e.bytesLoaded / e.bytesTotal * 100;
bar.setProgress(proc, 100);
bar.label= "当前进度: " + " " + proc + "%";
}

private function proceedWithUpload(e: CloseEvent): void{
if (e.detail == Alert.YES){
var request: URLRequest = new URLRequest("http://pc2010032013pib:8080/Upload/servlet/FileUploadServlet");
try {
file.upload(request);
} catch (error:Error) {
trace("上传失败");
}

}
}
]]>
</mx:Script>

<mx:Canvas width="100%" height="100%" x="10" y="170" fontSize="15">
<mx:VBox width="100%" horizontalAlign="center">
<mx:Label id="lbProgress" text="上传"/>
<mx:ProgressBar id="bar" labelPlacement="bottom" themeColor="#F20D7A"
minimum="0" visible="true" maximum="100" label="当前进度: 0%" 
direction="right" mode="manual" width="200"/>

<mx:Button label="上传文件" click="upload();"/> 
</mx:VBox>
</mx:Canvas>
</mx:Application>

import java.io.*;
import java.util.*;


import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.commons.fileupload.FileItem;
import org.apache.commons.fileupload.FileUploadException;
import org.apache.commons.fileupload.disk.DiskFileItemFactory;
import org.apache.commons.fileupload.servlet.ServletFileUpload;

/**
 *
 * @author crystal
 */
public class FileUploadServlet extends HttpServlet {

    /** 
     * Processes requests for both HTTP <code>GET</code> and <code>POST</code> methods.
     * @param request servlet request
     * @param response servlet response
     */
    // 定义文件的上传路径
    private String uploadPath = "E:\\upload\\";

// 限制文件的上传大小
    private int maxPostSize = 1024 * 1024 * 1024;

    public FileUploadServlet() {
        super();
    }

    public void destroy() {
        super.destroy();
    }

    protected void processRequest(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        System.out.println("Access !");
        response.setContentType("text/html;charset=UTF-8");
        PrintWriter out = response.getWriter();

        DiskFileItemFactory factory = new DiskFileItemFactory();
        factory.setSizeThreshold(4096);
        ServletFileUpload upload = new ServletFileUpload(factory);
        upload.setSizeMax(maxPostSize);
        try {
         [color=#FF0000]   List fileItems = upload.parseRequest(request);[/color]
            Iterator iter = fileItems.iterator();
            while (iter.hasNext()) {
                FileItem item = (FileItem) iter.next();
                if (!item.isFormField()) {
                    String name = item.getName();
                    System.out.println(name);
                    try {
                        item.write(new File(uploadPath + name));
               [color=#00FF00]   //      SaveFile s = new SaveFile();
                  //      s.saveFile(name);[/color]                        
                    } catch (Exception e) {
                        e.printStackTrace();
                       
                    }
                }
            }
        } catch (FileUploadException e) {
            e.printStackTrace();
            System.out.println(e.getMessage() + "结束");
        }
    }

    // <editor-fold defaultstate="collapsed" desc="HttpServlet methods. Click on the + sign on the left to edit the code.">
    /** 
     * Handles the HTTP <code>GET</code> method.
     * @param request servlet request
     * @param response servlet response
     */
    protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        processRequest(request, response);
    }

    /** 
     * Handles the HTTP <code>POST</code> method.
     * @param request servlet request
     * @param response servlet response
     */
    protected void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        processRequest(request, response);
    }
}