java file upload and download code example

In this article, we share the specific code of uploading and downloading java files for your reference. The specific contents are as follows

File upload

@RequestMapping(value="/uploadFile",method=RequestMethod.POST)
 public ResultObject uploadFiles(@RequestParam("file")MultipartFile file,HttpServletRequest request){
    ResultObject rs = null;// Return upload completion information 
    String uploadDir = "files";// Upload directory , Files are saved in webapp Under files In a file 
   if(!file.isEmpty()) {
     // Can be right user Do 1 Some operations such as storing in the database 
     // The following code is to set the file file Rename and save to Tomcat Adj. webapp Subdirectory of the project under the directory 
     String fileRealName = file.getOriginalFilename();          // Get the original file name ;
     /*int pointIndex = fileRealName.indexOf(".");            // Position of the dot 
     String fileSuffix = fileRealName.substring(pointIndex);       // Intercept file suffix 
     UUID FileId = UUID.randomUUID();            // The prefix of the generated file contains a hyphen 
     String savedFileName = FileId.toString().replace("-", "").concat(fileSuffix);    // File access name 
     */
     
     String savedDir = request.getSession().getServletContext().getRealPath(uploadDir); // Gets the file access path specified by the server 
     File savedFile = new File(savedDir, fileRealName);
     boolean isCreateSuccess;
     try {
       isCreateSuccess = savedFile.createNewFile();
       if (isCreateSuccess) {

         file.transferTo(savedFile); // Transfer document 
         rs = ResultObject.getSuccessResult(" Upload File Successfully ");
         Long size = file.getSize();// Get the file size 


         rs.setData(uploadDir+fileRealName);
       }else{
         rs = ResultObject.getFailResult(" Please modify the file name , Re-upload ");
       }
     } catch (IOException e) {
       e.printStackTrace();
     }
   }else{
     rs = ResultObject.getFailResult(" File cannot be empty ");
   }
   return rs;
 }

File download

@RequestMapping(value = "/filterPermission/appDownLoad", method = RequestMethod.GET)
  public void appDownLoad(HttpServletRequest request, HttpServletResponse response) {
    //url It was uploaded from the above file url
    download(url,request,response);
  }

public String download(String filePath, HttpServletRequest request, HttpServletResponse response) {
    BufferedInputStream bis = null;
    BufferedOutputStream bos = null;
    try {
      // Get the file name 
      String fileName = filePath.substring(filePath.lastIndexOf("/")+1);
      response.setCharacterEncoding("utf-8");
      response.setContentType("application/octet-stream");
      //response.setContentType("application/force-download");
      // Dealing with the encoding of download pop-up box names 
      response.setHeader("Content-Disposition", "attachment;fileName="
          + new String( fileName.getBytes("gb2312"), "ISO8859-1" ));
      // Get the download path of the file 
      String path = request.getSession().getServletContext().getRealPath(filePath);
      // Download files using input and output streams 
      InputStream inputStream = new FileInputStream(new File(path));
      // Set file size 
      response.setHeader("Content-Length", String.valueOf(inputStream.available()));

      bis = new BufferedInputStream(inputStream);// Construct a read stream 
      bos = new BufferedOutputStream(response.getOutputStream());// Construct output stream 
      byte[] buff = new byte[1024];
      int bytesRead;
      // Every time you read the cache size stream, write to the output stream 
      while (-1 != (bytesRead = bis.read(buff, 0, buff.length))) {
        bos.write(buff, 0, bytesRead);
      }
      response.flushBuffer();// Return all read streams to the client 

    } 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(" Failed to download file ,"+" File path :"+filePath+e);
        logger.error(" File download failed !", e);
      }
    }
    //  Pay attention to the return value, or the following error will appear! 
    //java+getOutputStream() has already been called for this response
    return null;
  }