在enctype =“multipart / form-data”请求不起作用之后

Question

<div id="apDiv12">
  <form id="form4" class="well" name="form4" method="post" action="product" enctype="multipart/form-data">
     <select name="catogory" id="catogory" >
        <option value="Select your catogory" selected="1">Select your catogory</option>
        <option value="Classical">Classical</option>
        <option value="Rock">Rock</option>
        <option value="R&B">R&B </option>
        <option value="Hio Hop">Hio Hop</option>
        <option value="Jazz">Jazz</option>
        <option value="Country">Country</option>
        <option value="Rap">Rap</option>
        <option value="Reggae">Reggae</option>>
     </select>

  <div id="apDiv17">
  <div id="apDiv18">Upload lyrics file..</div>
  <div id="apDiv19">Upload voice track..</div>
  <div id="apDiv20">Submit..</div>
  <div id="apDiv21"><input class="span3" name="lyrics" type="file" /></div>
  <div id="apDiv22"><input class="span3" name="voice" type="file" /></div>
  <div id="apDiv23"><input class="btn btn-primary" type="submit" name="upload" id="upload" value="Submit" /></div>
</div>
</form>

但是这个代码我得到null值.... 在这种情况下，值传递在doGet方法中工作。但文件上传无效。

私人决赛字符串UPLOAD_DIRECTORY =“/ media / shanaka / New Volume / munity”;

@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {

    PrintWriter writer = resp.getWriter();
    String catogary = req.getParameter("catogory");
    writer.print(catogary);
    //process only if its multipart content
    if (ServletFileUpload.isMultipartContent(req)) {
        try {

            List<FileItem> multiparts = new ServletFileUpload(
                    new DiskFileItemFactory()).parseRequest(req);

            for (FileItem item : multiparts) {
                if (!item.isFormField()) {
                    String name = new File(item.getName()).getName();
                    item.write(new File(UPLOAD_DIRECTORY + File.separator + name));

                }
            }

            //File uploaded successfully
            req.setAttribute("message", "File Uploaded Successfully");
        } catch (Exception ex) {
            req.setAttribute("message", "File Upload Failed due to " + ex);
        }

    } else {
        req.setAttribute("message",
                "Sorry this Servlet only handles file upload request");
    }


}

我已经尝试将@MultipartConfig放在servlet中，但是Category Field为null。