java文件上传下载代码实例

@RequestMapping(value="/uploadFile",method=RequestMethod.POST)
 public ResultObject uploadFiles(@RequestParam("file")MultipartFile file,HttpServletRequest request){
    ResultObject rs = null;//返回上传完成信息
    String uploadDir = "files";//上传目录,文件保存在webapp下的files文件中
   if(!file.isEmpty()) {
     //可以对user做一些操作如存入数据库
     //以下的代码是将文件file重新命名并存入Tomcat的webapp目录下项目的下级目录
     String fileRealName = file.getOriginalFilename();          //获得原始文件名;
     /*int pointIndex = fileRealName.indexOf(".");            //点号的位置
     String fileSuffix = fileRealName.substring(pointIndex);       //截取文件后缀
     UUID FileId = UUID.randomUUID();            //生成文件的前缀包含连字符
     String savedFileName = FileId.toString().replace("-", "").concat(fileSuffix);    //文件存取名
     */
     
     String savedDir = request.getSession().getServletContext().getRealPath(uploadDir); //获取服务器指定文件存取路径
     File savedFile = new File(savedDir, fileRealName);
     boolean isCreateSuccess;
     try {
       isCreateSuccess = savedFile.createNewFile();
       if (isCreateSuccess) {

         file.transferTo(savedFile); //转存文件
         rs = ResultObject.getSuccessResult("上传文件成功");
         Long size = file.getSize();//获取文件大小


         rs.setData(uploadDir+fileRealName);
       }else{
         rs = ResultObject.getFailResult("请修改文件名,重新上传");
       }
     } catch (IOException e) {
       e.printStackTrace();
     }
   }else{
     rs = ResultObject.getFailResult("文件不能为空");
   }
   return rs;
 }

@RequestMapping(value = "/filterPermission/appDownLoad", method = RequestMethod.GET)
  public void appDownLoad(HttpServletRequest request, HttpServletResponse response) {
    //url是上面文件上传的url
    download(url,request,response);
  }

public String download(String filePath, HttpServletRequest request, HttpServletResponse response) {
    BufferedInputStream bis = null;
    BufferedOutputStream bos = null;
    try {
      //获取文件名
      String fileName = filePath.substring(filePath.lastIndexOf("/")+1);
      response.setCharacterEncoding("utf-8");
      response.setContentType("application/octet-stream");
      //response.setContentType("application/force-download");
      //处理下载弹出框名字的编码问题
      response.setHeader("Content-Disposition", "attachment;fileName="
          + new String( fileName.getBytes("gb2312"), "ISO8859-1" ));
      //获取文件的下载路径
      String path = request.getSession().getServletContext().getRealPath(filePath);
      //利用输入输出流对文件进行下载
      InputStream inputStream = new FileInputStream(new File(path));
      //设置文件大小
      response.setHeader("Content-Length", String.valueOf(inputStream.available()));

      bis = new BufferedInputStream(inputStream);//构造读取流
      bos = new BufferedOutputStream(response.getOutputStream());//构造输出流
      byte[] buff = new byte[1024];
      int bytesRead;
      //每次读取缓存大小的流，写到输出流
      while (-1 != (bytesRead = bis.read(buff, 0, buff.length))) {
        bos.write(buff, 0, bytesRead);
      }
      response.flushBuffer();//将所有的读取的流返回给客户端

    } catch (FileNotFoundException e) {
      e.printStackTrace();
    } catch (IOException e) {
      e.printStackTrace();
    }finally{
      try{
        if(null != bis){
          bis.close();
        }
        if(null != bos){
          bos.close();
        }
      }catch(IOException e){
        System.out.println("下载文件失败,"+"文件路径:"+filePath+e);
        logger.error("文件下载失败!", e);
      }
    }
    // 返回值要注意，要不然就出现下面这句错误！
    //java+getOutputStream() has already been called for this response
    return null;
  }