使用commons-fileupload.jar进行文件上传源码

 public void uploadFile(HttpServletRequest requset, HttpServletResponse response) throws Exception {
      response.setHeader("Access-Control-Allow-Origin", "*"); 
      response.setHeader("Access-Control-Allow-Methods", "POST");
  DiskFileItemFactory factory = new DiskFileItemFactory();
      ServletFileUpload up = new ServletFileUpload(factory);
      PrintWriter out = response.getWriter();
      //文件保存地址
      String savePath = requset.getServletContext().getRealPath("/picture");
      File file = new File(savePath);
  // 如果文件夹不存在则创建
  if (!file.exists() && !file.isDirectory()) {
  file.mkdir();
  }
  List fileItemList = up.parseRequest(requset);
  for (FileItem fileItem : fileItemList) {
  if (!fileItem.isFormField()) {
  String saveName = savePath+File.separator+fileItem.getName();
  String lastName = saveName.substring(saveName.lastIndexOf(".")+1);
  if(!(lastName.equals("jpg")||lastName.equals("BMP")||lastName.equals("gif")||lastName.equals("JPEG"))) {
  Map reMap = new HashMap();
  reMap.put("resultCode","999999");
  reMap.put("resultMsg", "文件格式不正确,上传失败");
  out = response.getWriter();
  out.println(reMap.toString());
  out.flush();
  out.close();
  }else {
  Long big = System.currentTimeMillis();
  File fileName = new File(savePath+File.separator+big+".jpg");
  fileName.createNewFile();
  fileItem.write(fileName);
  }
  }
  }
     }