EXTJS 文件上传 后台文件上传成功，前台页面提示传输失败？

这个是我的上传页面playerUpload.jsp：
<html>  
<head>  
<%@ page language="java" contentType="text/html; charset=utf-8"  pageEncoding="utf-8"%>  
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />  
<title>上传页面</title>  
 
<script type="text/javascript" src="../../scripts/ext/adapter/ext/ext-base.js"></script>
<script type="text/javascript" src="../../scripts/ext/ext-all.js"></script>
<link rel="stylesheet" type="text/css" href="../../scripts/ext/resources/css/ext-all.css" />


<link rel="stylesheet" type="text/css" href="../../UploadDialog/css/Ext.ux.UploadDialog.css" />
<script type="text/javascript" src="../../UploadDialog/Ext.ux.UploadDialog.js"></script>
<script type="text/javascript" src="../../UploadDialog/Ext.ux.UploadDialog.packed.js"></script>
   <script type="text/javascript" src="../../UploadDialog/locale/zh_CN.js"></script>
 
 <script type="text/javascript">  
 Ext.onReady(function() {   
    var dialog = new Ext.ux.UploadDialog.Dialog({   
        autoCreate: true,   
        closable: true,   
        collapsible: false,   
        draggable: true,   
        minWidth: 400,   
        minHeight: 200,   
        width: 400,   
        height: 350, 
       
        proxyDrag: true,    
        resizable: true,   
        constraintoviewport: true,   
        url: '/page/playerUpload/uploadJSPBack.jsp',   
        reset_on_hide: false,   
        allow_close_on_upload: true   
        });   
    dialog.show();    
 });   
    
</script>  
</head>  
<body>  
  
</body>  
</html>  这个是处理数据的页面：uploadJSPBack.jsp
<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%>  
<%@ page import="java.io.*" %>  
<%@ page import="boyce.cn.common.db.DbParamFields" %>  
<%@ page import="java.util.Enumeration" %>  
<%@ page import="com.hznovel.web.common.processor.SystemProcessor" %>  
<%@ page import="com.oreilly.servlet.MultipartRequest" %>  
<%@ page contentType="text/html;charset=utf-8" %>  
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">  <html>  
    <head>  
        <title>上传后台页面</title>  
        <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />  
<%   
           try {
            String path = request.getRealPath("/playerUpload");
          
SystemProcessor d = new SystemProcessor();
// 每个文件最大5m,最多3个,所以总文件大小为(以字节为单位)
int maxPostSize = 3 * 5 * 1024 * 1024;
// 保存文件 response的编码为utf-8,
MultipartRequest multi =new MultipartRequest(request, path, maxPostSize, "utf-8");
// 输出反馈信息
Enumeration files =multi.getFileNames();
while (files.hasMoreElements()) {
String name = (String) files.nextElement();
File f = multi.getFile(name);
if (f != null) {
String fileName = multi.getFilesystemName(name); // 获得文件名
String lastFileName = path + "\\" + fileName; // 显示保存路径
System.out.println(lastFileName);
String fileNamepath="playerUpload/"+fileName;
                    DbParamFields params = new DbParamFields();
params.addInString(fileName);
params.addInString(fileNamepath);
d.execProcedure("DeviceInfo.playerUpload",params);
d.disconnect();
d.commit();
out.close();
response.getWriter().print("上传的文件:" + lastFileName);
response.getWriter().print("<hr>");
}
}
System.out.println("上传成功");
response.setContentType("text/html;charset=utf-8");
response.getWriter().print(
"{'success':true,'message':'上传成功'}");
} catch (Exception e) {
 e.printStackTrace();
System.out.println("上传失败");
try {
response.getWriter().print(
"{'success':false,'message':'上传失败'}");
} catch (IOException e1) {
e1.printStackTrace();
}
}

%>  
    </head>  
  
    <body>           
    </body>  
</html>