如何使用java實(shí)現文件上傳、下載、圖片預覽功能

小編給大家分享一下如何使用java實(shí)現文件上傳、下載、圖片預覽功能，相信大部分人都還不怎么了解，因此分享這篇文章給大家參考一下，希望大家閱讀完這篇文章后大有收獲，下面讓我們一起去了解一下吧！

多文件保存到本地：

@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";    }  }

下載文件：

@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; // 文件的默認保存名    InputStream inStream = new FileInputStream(path);// 文件的存放路徑    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();    }  }   /**   * 讀取圖片   */  @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();      }    }  }

前端請求直接拼接圖片路徑即可。