springMVC 实现上传文件和下载文件

第一步：在applicationContext.xml中添加支持<!-- 支持文件上传 --><bean id="multipartResolver" class="org.springframework.web.multipart.commons.CommonsMultipartResolver"></bean>

第二步:

/**     * 上传文件     *     * @param file     * @param request     * @param model     * @return     */    @RequestMapping(value = "/upload")    public String upload(@RequestParam(value = "file", required = false) MultipartFile file, HttpServletRequest request, ModelMap model) {        //如果文件为空则返回uploadTxt.jsp        if (file.isEmpty()) {            return "uploadTxt";        }        System.out.println("start upload file");        String path = request.getSession().getServletContext().getRealPath("upload");        String fileName = file.getOriginalFilename();//        //如果文件格式不是txt，返回uploadTxt.jsp//        if (!fileName.endsWith("txt")) {//            return "uploadTxt";//        }        System.out.println("fileName====>  " + fileName);//        String fileName = new Date().getTime()+".jpg";        System.out.println("file path:" + path);        File targetFile = new File(path, fileName);        if (!targetFile.exists()) {            //创建目录            targetFile.mkdirs();        }        try {            file.transferTo(targetFile);        } catch (Exception e) {            e.printStackTrace();        }        model.addAttribute("fileUrl", request.getContextPath() + "/upload/" + fileName);        return "forward:/list";    }

/**     * 获取上传路径上的所有文件     *     * @param request     * @return     */    @RequestMapping("/listFile")    public ModelAndView list(HttpServletRequest request) {        String filePath = request.getSession().getServletContext().getRealPath("/") + "upload/";        ModelAndView modelAndView = new ModelAndView();        File uploadDest = new File(filePath);        String[] fileNames = uploadDest.list();//        for (int i = 0; i < fileNames.length; i++) {//            //输出所有文件名//            System.out.println(fileNames[i]);//        }        String jsonString = JSON.toJSONString(fileNames);        modelAndView.addObject("fileNamesJsonString", jsonString);        System.out.println(jsonString);        modelAndView.setViewName("listFile");        return modelAndView;    }

/** * download File * * @param request * @param fileName * @return * @throws IOException */@RequestMapping("/download")public ResponseEntity<byte[]> download(HttpServletRequest request, @RequestParam("fileName") String fileName) throws IOException {    String path = request.getServletContext().getRealPath("/upload/");    File dwFile = new File(path + File.separator + fileName);    HttpHeaders headers = new HttpHeaders();    //下载显示的中文名，解决中文名称乱码问题    String downloadFileName = new String(fileName.getBytes("UTF-8"), "ISO-8859-1");    //application/octet-stream:二进制流数据    headers.setContentDispositionFormData("attachment", downloadFileName);    headers.setContentType(MediaType.APPLICATION_OCTET_STREAM);    return new ResponseEntity<byte[]>(FileUtils.readFileToByteArray(dwFile), headers, HttpStatus.CREATED);}