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。