java web上传文件和下载文件代码片段分享

本文实例为大家分享了java web上传文件和下载文件的具体代码，供大家参考，具体内容如下

 /**
  * Purpose：上传文档
  *
  * @param req
  * @param fileTitle
  * @param fileType
  * @param fileDesc
  * @return
  */
 @RequestMapping("upload")
 public ModelAndView upload(HttpServletRequest req, String fileType, String fileDesc, String share) {
  UserAllInfo userAll = (UserAllInfo) req.getSession().getAttribute("userAll");
  ModelAndView mav = new ModelAndView();
  // 获取文件的大小
  String fileSize = "";
  int length = req.getContentLength();
  //转换成KB
  double len1 = (double) (Math.round((length / 1024) * 100)) / 100;
  //转换成MB
  double len2 = (double) (Math.round((len1 / 1024) * 100)) / 100;
  if (len2 > 1) {
   fileSize = String.valueOf(len2) + "MB";
  } else {
   fileSize = String.valueOf(len1) + "KB";
  }
  //将请求转换成处理文件的请求
  MultipartRequest mreq = (MultipartRequest) req;
  //文件上传专用类
  MultipartFile mfile = mreq.getFile("uploadFile");

  // 得到上下文路径
  String root = req.getSession().getServletContext().getRealPath("/");
  File dir = new File(root);
  // 获取文件名和文件的mime类型
  String str = mfile.getOriginalFilename();
  String[] st = str.split("\\.");

  File savedFile = null;
  try {
   //在指定目录中创建一个新的空文件，文件名称加前缀"upload_"
   savedFile = File.createTempFile("upload_", mfile.getOriginalFilename(), dir);
   //将缓冲区的内容复制到新创建的文件中
   FileCopyUtils.copy(mfile.getInputStream(), new FileOutputStream(savedFile));
  } catch (Exception e) {
   e.printStackTrace();
  }
  String path = savedFile.getPath();

  // 将文件的信息封装在对象中
  FileInfo file = new FileInfo();
  if (userAll != null) {
   file.setUploadPersonId(userAll.getUser().getUserId());
  } else {
   mav.setViewName("login");
   return mav;
  }
  file.setFileName(st[0]);
  file.setFilePath(path);
  Date date = new Date();
  file.setUploadDate(date);
  file.setFileSize(fileSize);
  file.setFileType(fileType);
  file.setFileForm(st[1]);
  if ("superman".equals(userAll.getUser().getUserNumber())) {
   file.setFileShare("Y");
   file.setCheckFlag("Y");
  } else {
   file.setFileShare(share);
   file.setCheckFlag("N");
  }
  file.setDeleteFlag("N");
  file.setDownloadTimes(0);
  // 保存文件的信息
  boolean bool = fileSer.saveFile(file);
  String userNumber = userAll.getUser().getUserNumber();
  //设置跳转界面
  mav.setViewName("jsp/person/upload");
  logSer.saveLog("用户\"" + userNumber + "\"上传文件\"" + file.getFileName() + "\"");
  mav.getModel().put("bool", bool);
  return mav;
 }

 /**
  * Purpose：下载文档
  *
  * @param fileId 文件id
  * @return
  */
 @RequestMapping("download")
 public void download(Integer fileId, HttpServletResponse resp) {
  FileInfo file = new FileInfo();
  //通过文件id获取文件的基本信息
  file = fileSer.getFileById(fileId);

  // 根据文件后缀名设置文件的mime类型
  String mime = "application/";
  switch (file.getFileForm()) {
  case "doc":
   mime = mime + "msword";
   break;
  case "docx":
   mime = mime + "msword";
   break;
  case "pdf":
   mime = mime + "pdf";
   break;
  case "xls":
   mime = mime + "vnd.ms-excel";
  case "ppt":
   mime = mime + "vnd.ms-powerpoint";
   break;
  case "txt":
   mime = "text/plain";
   break;
  default:
   break;
  }
  resp.setContentType(mime);
  String fileName = file.getFileName();
  String name = "";
  try {
   // 将文件名使用utf-8编码格式编码，使其中的中文字符可以正常显示
   name = URLEncoder.encode(fileName, "utf-8");
  } catch (UnsupportedEncodingException e1) {
   e1.printStackTrace();
  }

  // 弹框选择保存路径
  resp.setHeader("content-disposition", "attachment;filename=" + name + "." + file.getFileForm()
    + ";filename*=utf-8''" + name + "." + file.getFileForm());

  String filePath = file.getFilePath();
  InputStream is = null;
  OutputStream os = null;
  try {
   is = new BufferedInputStream(new FileInputStream(filePath));
   os = new BufferedOutputStream(resp.getOutputStream());
   byte[] buff = new byte[1024];
   @SuppressWarnings("unused")
   int count;
   while ((count = is.read(buff)) != -1) {
    os.write(buff);
   }
   //修改下载次数
   fileSer.update(fileId);
  } catch (Exception e) {
   e.printStackTrace();
  } finally {
   //最后，要记得关闭输入流和输出流
   if (is != null) {
    try {
     is.close();
    } catch (IOException e) {
     e.printStackTrace();
    }
   }
   if (os != null) {
    try {
     os.close();
    } catch (IOException e) {
     e.printStackTrace();
    }
   }
  }
 }

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持我们。