java后台返还参数给js页面问题

需要做一个网页上传图片保存本地,并上传给算法,算法再返回参数给后台,再由后台返回给页面显示,由于jsp页面是别人用js写的,现在参数返回给页面的时候貌似页面不会跳转.求解决方法.

这是后台

 public String plupload(@RequestParam MultipartFile file, HttpServletRequest request, HttpSession session) {
        try {
            String name = request.getParameter("name");
            Integer chunk = 0, chunks = 0;
            if(null != request.getParameter("chunk") && !request.getParameter("chunk").equals("")){
                chunk = Integer.valueOf(request.getParameter("chunk"));
            }
            if(null != request.getParameter("chunks") && !request.getParameter("chunks").equals("")){
                chunks = Integer.valueOf(request.getParameter("chunks"));
            }
            logger.info("chunk:[" + chunk + "] chunks:[" + chunks + "]");
            //检查文件目录，不存在则创建
            String relativePath = "E:\\Pic\\";
            //String realPath = session.getServletContext().getRealPath("");
            File folder = new File(relativePath);
            if (!folder.exists()) {
                folder.mkdirs();
            }

            //目标文件 
            File destFile = new File(folder, name);
            //文件已存在删除旧文件（上传了同名的文件） 
            if (chunk == 0 && destFile.exists()) {  
                destFile.delete();  
                destFile = new File(folder, name);
            }
            //合成文件
            appendFile(file.getInputStream(), destFile);  
            if (chunk == chunks - 1) {  
                logger.info("上传完成");
             // 预留启动socket传输地址,relativePath +name

                MD5=Client.Out(relativePath+name);

                request.setAttribute("MD5", MD5);

                return "index";


            }else {
                logger.info("还剩["+(chunks-1-chunk)+"]个块文件");
            }

        } catch (IOException e) {
            logger.error(e.getMessage());
        }
        return "";
    }

这是JSP代码

 <body>
    <div id="uploader">
        <p>Your browser doesn't have Flash, Silverlight or HTML5 support.</p>
    </div>
    <script type="text/javascript">

        $(function() {
            $("#uploader").plupload({
                runtimes : 'html5,flash,silverlight,html4',
                url : "plupload",
                // url : "pluploadservlet", //servlet版本
                // Maximum file size
                max_file_size : '1024mb',
                chunk_size : '10mb',
                // Resize images on clientside if we can
                resize : {
                    width : 200,
                    height : 200,
                    quality : 90,
                    crop : true
                },
                // Specify what files to browse for
                filters : [ {
                    title : "Image files",
                    extensions : "jpg,gif,png"
                }, {
                    title : "Zip files",
                    extensions : "zip,rar"
                } ],
                // Rename files by clicking on their titles
                rename : true,
                // Sort files
                sortable : true,
                // Enable ability to drag'n'drop files onto the widget (currently only HTML5 supports that)
                dragdrop : true,
                // Views to activate
                views : {
                    list : true,
                    thumbs : true, // Show thumbs
                    active : 'thumbs'
                },
                // Flash settings
                flash_swf_url : 'static/plupload/js/Moxie.swf',
                // Silverlight settings
                silverlight_xap_url : 'static/plupload/js/Moxie.xap'
            });
        });

    </script>
    <script type="text/javascript" src="static/plupload/js/jquery-ui.min.js" charset="UTF-8"></script>
    <script type="text/javascript" src="static/plupload/js/plupload.full.min.js" charset="UTF-8"></script>
    <script type="text/javascript" src="static/plupload/js/i18n/zh_CN.js"></script>
    <script type="text/javascript" src="static/plupload/js/jquery.ui.plupload/jquery.ui.plupload.min.js" charset="UTF-8"></script>
    <center>

        <h5>MD5计算结果：</h5>
        <%=MD5%>

    </center>


</body>

图片说明

如图上传完MD5并没有刷新,求解决方法

你可以在网上看看关于Plupload插件的api，看看有没有接受参数的方法