• controller
  
• service
  

实例代码：

• controller

  @Controller
  @RequestMapping("download")
  public class FileDownloadController {
  
      @Autowired
      FileDownloadService fileDownloadService;
  
      @GetMapping("article/{id}")
      public ResponseEntity<byte[]> downloadArticle(@PathVariable String id) {
          ResponseEntity<byte[]> result = fileDownloadService.downloadArticle(id);
          return result;
      }
  }
  

• service

  public ResponseEntity<byte[]> downloadArticle(String articleId) {
      Article article = articleService.get(articleId);
      byte[] data = null;
      // 将 article 保存到硬盘
      File file = fileDownloadService.saveArticleInDisk(article.getTitle() , article.getContent());
      try {
          data = FileUtil.toByteArray(file.getAbsolutePath());
      } catch (IOException e) {
          e.printStackTrace();
      }
      String fileName = file.getName() ;
      HttpHeaders headers = new HttpHeaders();
      headers.setContentType(MediaType.APPLICATION_OCTET_STREAM);
      try {
          headers.setContentDispositionFormData("attachment", URLEncoder.encode(fileName,"utf-8"));
      } catch (UnsupportedEncodingException e) {
          e.printStackTrace();
      }
      return new ResponseEntity<byte[]>( data , headers , HttpStatus.CREATED);
  }