// 单文件上传
@RequestMapping(value = "/upload")
@ResponseBody
public String upload(@RequestParam("file") MultipartFile file) {try {if (file.isEmpty()) {return "文件为空";}// 获取文件名String fileName = file.getOriginalFilename();logger.info("上传的文件名为：" + fileName);// 获取文件的后缀名String suffixName = fileName.substring(fileName.lastIndexOf("."));logger.info("文件的后缀名为：" + suffixName);// 设置文件存储路径String filePath = "D://aim//";String path = filePath + fileName + suffixName;File dest = new File(path);// 检测是否存在目录if (!dest.getParentFile().exists()) {dest.getParentFile().mkdirs();// 新建文件夹
    }file.transferTo(dest);// 文件写入return "上传成功";} catch (IllegalStateException e) {e.printStackTrace();} catch (IOException e) {e.printStackTrace();}return "上传失败";
}

//多文件上传
@RequestMapping(value = "/uploadMore", method = RequestMethod.POST)
@ResponseBody
public String handleFileUpload(HttpServletRequest request) {List<MultipartFile> files = ((MultipartHttpServletRequest) request).getFiles("file");MultipartFile file = null;BufferedOutputStream stream = null;for (int i = 0; i < files.size(); ++i) {file = files.get(i);String filePath = "D://aim//";if (!file.isEmpty()) {try {byte[] bytes = file.getBytes();stream = new BufferedOutputStream(new FileOutputStream(new File(filePath + file.getOriginalFilename())));//设置文件路径及名字stream.write(bytes);// 写入
                stream.close();} catch (Exception e) {stream = null;return "第 " + i + " 个文件上传失败  ==> "+ e.getMessage();}} else {return "第 " + i+ " 个文件上传失败因为文件为空";}}return "上传成功";
}

//文件下载相关代码
@RequestMapping("/download")
public String downloadFile(HttpServletRequest request, HttpServletResponse response) {String fileName = "aim_test.txt";// 设置文件名，根据业务需要替换成要下载的文件名if (fileName != null) {//设置文件路径String realPath = "D://aim//"File file = new File(realPath , fileName);if (file.exists()) {response.setContentType("application/force-download");// 设置强制下载不打开response.addHeader("Content-Disposition", "attachment;fileName=" + fileName);// 设置文件名byte[] buffer = new byte[1024];FileInputStream fis = null;BufferedInputStream bis = null;try {fis = new FileInputStream(file);bis = new BufferedInputStream(fis);OutputStream os = response.getOutputStream();int i = bis.read(buffer);while (i != -1) {os.write(buffer, 0, i);i = bis.read(buffer);}System.out.println("success");} catch (Exception e) {e.printStackTrace();} finally {if (bis != null) {try {bis.close();} catch (IOException e) {e.printStackTrace();}}if (fis != null) {try {fis.close();} catch (IOException e) {e.printStackTrace();}}}}}return null;
}