@RequestMapping(value="/uploadFile",method=RequestMethod.POST)
 public ResultObject uploadFiles(@RequestParam("file")MultipartFile file,HttpServletRequest request){
    ResultObject rs = null;//返回上傳完成信息
    String uploadDir = "files";//上傳目錄,文件保存在webapp下的files文件中
   if(!file.isEmpty()) {
     //可以對user做一些操作如存入數據庫
     //以下的代碼是將文件file重新命名并存入Tomcat的webapp目錄下項目的下級目錄
     String fileRealName = file.getOriginalFilename();          //獲得原始文件名;
     /*int pointIndex = fileRealName.indexOf(".");            //點號的位置
     String fileSuffix = fileRealName.substring(pointIndex);       //截取文件后綴
     UUID FileId = UUID.randomUUID();            //生成文件的前綴包含連字符
     String savedFileName = FileId.toString().replace("-", "").concat(fileSuffix);    //文件存取名
     */
     
     String savedDir = request.getSession().getServletContext().getRealPath(uploadDir); //獲取服務器指定文件存取路徑
     File savedFile = new File(savedDir, fileRealName);
     boolean isCreateSuccess;
     try {
       isCreateSuccess = savedFile.createNewFile();
       if (isCreateSuccess) {

         file.transferTo(savedFile); //轉存文件
         rs = ResultObject.getSuccessResult("上傳文件成功");
         Long size = file.getSize();//獲取文件大小


         rs.setData(uploadDir+fileRealName);
       }else{
         rs = ResultObject.getFailResult("請修改文件名,重新上傳");
       }
     } catch (IOException e) {
       e.printStackTrace();
     }
   }else{
     rs = ResultObject.getFailResult("文件不能為空");
   }
   return rs;
 }

@RequestMapping(value = "/filterPermission/appDownLoad", method = RequestMethod.GET)
  public void appDownLoad(HttpServletRequest request, HttpServletResponse response) {
    //url是上面文件上傳的url
    download(url,request,response);
  }

public String download(String filePath, HttpServletRequest request, HttpServletResponse response) {
    BufferedInputStream bis = null;
    BufferedOutputStream bos = null;
    try {
      //獲取文件名
      String fileName = filePath.substring(filePath.lastIndexOf("/")+1);
      response.setCharacterEncoding("utf-8");
      response.setContentType("application/octet-stream");
      //response.setContentType("application/force-download");
      //處理下載彈出框名字的編碼問題
      response.setHeader("Content-Disposition", "attachment;fileName="
          + new String( fileName.getBytes("gb2312"), "ISO8859-1" ));
      //獲取文件的下載路徑
      String path = request.getSession().getServletContext().getRealPath(filePath);
      //利用輸入輸出流對文件進行下載
      InputStream inputStream = new FileInputStream(new File(path));
      //設置文件大小
      response.setHeader("Content-Length", String.valueOf(inputStream.available()));

      bis = new BufferedInputStream(inputStream);//構造讀取流
      bos = new BufferedOutputStream(response.getOutputStream());//構造輸出流
      byte[] buff = new byte[1024];
      int bytesRead;
      //每次讀取緩存大小的流，寫到輸出流
      while (-1 != (bytesRead = bis.read(buff, 0, buff.length))) {
        bos.write(buff, 0, bytesRead);
      }
      response.flushBuffer();//將所有的讀取的流返回給客戶端

    } catch (FileNotFoundException e) {
      e.printStackTrace();
    } catch (IOException e) {
      e.printStackTrace();
    }finally{
      try{
        if(null != bis){
          bis.close();
        }
        if(null != bos){
          bos.close();
        }
      }catch(IOException e){
        System.out.println("下載文件失敗,"+"文件路徑:"+filePath+e);
        logger.error("文件下載失敗!", e);
      }
    }
    // 返回值要注意，要不然就出現下面這句錯誤！
    //java+getOutputStream() has already been called for this response
    return null;
  }