@RequestMapping(value = "file_upload.do", method = RequestMethod.POST)
	public void fileUpload(HttpServletRequest  request,
			HttpServletResponse response) throws ServletException, IOException,
			FileUploadException {
		ServletContext application = request.getSession().getServletContext();
		String savePath = application.getRealPath("/") + "attached/";

		// 文件保存目录URL
		String saveUrl = request.getContextPath() + "/attached/";

		// 定义允许上传的文件扩展名
		HashMap<String, String> extMap = new HashMap<String, String>();
		extMap.put("image", "gif,jpg,jpeg,png,bmp");
		extMap.put("flash", "swf,flv");
		extMap.put("media", "swf,flv,mp3,wav,wma,wmv,mid,avi,mpg,asf,rm,rmvb");
		extMap.put("file", "doc,docx,xls,xlsx,ppt,htm,html,txt,zip,rar,gz,bz2");

		// 最大文件大小
		long maxSize = 1000000;

		response.reset();
        response.setCharacterEncoding("UTF-8");
        response.setContentType("text/html");
        writer = response.getWriter();
       // writer.println(json);  //想办法把map转成json
		
		if (!ServletFileUpload.isMultipartContent(request)) {
			writer.println(objectMapper.writeValueAsString(getError("请选择文件。")));
			return;
			
		}
		// 检查目录
		File uploadDir = new File(savePath);
		if (!uploadDir.isDirectory()) {
			writer.println(objectMapper.writeValueAsString(getError("上传目录不存在。")));
			return;
		}
		// 检查目录写权限
		if (!uploadDir.canWrite()) {
			writer.println(objectMapper.writeValueAsString(getError("上传目录没有写权限。")));
			return;
		}

		String dirName = request.getParameter("dir");
		if (dirName == null) {
			dirName = "image";
		}
		if (!extMap.containsKey(dirName)) {
			writer.println(objectMapper.writeValueAsString(getError("目录名不正确。")));
			return;
		}
		// 创建文件夹
		savePath += dirName + "/";
		saveUrl += dirName + "/";
		File saveDirFile = new File(savePath);
		if (!saveDirFile.exists()) {
			saveDirFile.mkdirs();
		}
		SimpleDateFormat sdf = new SimpleDateFormat("yyyyMMdd");
		String ymd = sdf.format(new Date());
		savePath += ymd + "/";
		saveUrl += ymd + "/";
		File dirFile = new File(savePath);
		if (!dirFile.exists()) {
			dirFile.mkdirs();
		}

		FileItemFactory factory = new DiskFileItemFactory();
		ServletFileUpload upload = new ServletFileUpload(factory);
		upload.setHeaderEncoding("UTF-8");
		List items = upload.parseRequest(request);
		Iterator itr = items.iterator();
		while (itr.hasNext()) {
			FileItem item = (FileItem) itr.next();
			String fileName = item.getName();
			if (!item.isFormField()) {
				// 检查文件大小
				if (item.getSize() > maxSize) {
					writer.println(objectMapper.writeValueAsString(getError("上传文件大小超过限制。")));
				}
				// 检查扩展名
				String fileExt = fileName.substring(
						fileName.lastIndexOf(".") + 1).toLowerCase();
				if (!Arrays.<String> asList(extMap.get(dirName).split(","))
						.contains(fileExt)) {
					writer.println(objectMapper.writeValueAsString(getError("上传文件扩展名是不允许的扩展名。\n只允许"+ extMap.get(dirName) + "格式。")));
					return;
				}

				SimpleDateFormat df = new SimpleDateFormat("yyyyMMddHHmmss");
				String newFileName = df.format(new Date()) + "_"
						+ new Random().nextInt(1000) + "." + fileExt;
				try {
					File uploadedFile = new File(savePath, newFileName);
					item.write(uploadedFile);
				} catch (Exception e) {
					writer.println(objectMapper.writeValueAsString(getError("上传文件失败。")));
				}

				Map<String, Object> msg = new HashMap<String, Object>();
				msg.put("error", 0);
				msg.put("url", saveUrl + newFileName);
				writer.println(objectMapper.writeValueAsString(msg));
				return;
			}
		}
		return;
	}