Java realizes file upload, download and image preview

Time:2020-11-19

This article mainly introduces the Java implementation of file upload, download, image preview, the article through the example code is very detailed, for everyone’s study or work has a certain reference learning value, need friends can refer to

Save multiple files locally:


@ResponseBody
  @RequestMapping(value = "/uploadApp",produces = { "application/json;charset=UTF-8" },method= RequestMethod.POST)
  public String uploadApp( HttpServletRequest request,@RequestParam("file") MultipartFile[] file) throws IOException {
    try {
      if(file.length > 0) {
        String name = file[0].getOriginalFilename().split(";")[0];
        String fileUrlName = CommonEnum.FILEPATH+"/"+name;
        for (int i = 0; i < file.length; i++) {
          FileUtils.copyInputStreamToFile(file[i].getInputStream(), new File(fileUrlName, file[i].getOriginalFilename().split(";")[1]));
        }
        return "success";
      }else{
        return "null";
      }
    }catch (Exception e){
      e.printStackTrace();
      return "error";
    }
  }

Download File:

@RequestMapping(value = "/download", method = RequestMethod.GET)
  @ResponseBody
  public void download(@RequestParam Map<String, Object> data, HttpServletRequest request,HttpServletResponse response) throws FileNotFoundException {
    String time = DateUtil.formatFromDate("yyyyMMddHHmmss", new Date());
    List<Map<String, Object>> urllist = companyService.findByIMG(data);
    String path = (String) urllist.get(0).get("imgurl");
    String docx = StringUtils.substringAfterLast(path, ".");
    String filename = time + ". + docx; // the default save name of the file
    InputStream instream = new FileInputStream (path); // file storage path
    response.reset();
    response.setContentType("bin");
    response.addHeader("Content-Disposition", "attachment; filename=\"" + fileName + "\"");
    byte[] b = new byte[100];
    int len;
    try {
      while ((len = inStream.read(b)) > 0)
        response.getOutputStream().write(b, 0, len);
      inStream.close();
    } catch (IOException e) {
      e.printStackTrace();
    }

  }

 

  /**
   *Read picture
   */
  @RequestMapping(value = "/iomoreimgcom", produces = {
      "application/json;charset=UTF-8" }, method = RequestMethod.GET)
  @ResponseBody
  public synchronized void iomoreimgcom(HttpServletRequest request, HttpServletResponse response) throws Exception {
    String url = request.getParameter("url");
    File file = new File(url);
    BufferedInputStream bis = new BufferedInputStream(new FileInputStream(file));
    BufferedOutputStream bos = new BufferedOutputStream(response.getOutputStream());
    response.setHeader("Content-Type", "image/jpeg");
    byte b[] = new byte[1024];
    int read;
    try {
      while ((read = bis.read(b)) != -1) {
        bos.write(b, 0, read);
      }
      //request.getRequestDispatcher("/components/hazard/yscchird.html").forward(request, response);
    } catch (Exception e) {
      // TODO: handle exception
    } finally {
      if (bos != null) {
        bos.close();
      }
      if (bis != null) {
        bis.close();
      }
    }
  }

The front-end request directly stitches the picture path.

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