@RequestMapping("/addFile")
@ResponseBody
public String addFile(){
    MongoClient client = new MongoClient("127.0.0.1",27017);
    DB db = client.getDB("files");
    GridFS fs = new GridFS(db);
    try {
      GridFSInputFile gridFSInputFile = fs.createFile(new File("D://test.png"));
      gridFSInputFile.setFilename("db_test.png");
      gridFSInputFile.save();
    } catch (IOException e) {
      e.printStackTrace();
    }
    return "file over";
}

@RequestMapping("/downFile")
  public void downFile(HttpServletResponse response){
    String fileId = "5c0f7c374fc404123403d69e";//這里可以通過參數(shù)取代
    try {
      MongoClient client = new MongoClient("127.0.0.1",27017);
      DB db = client.getDB("files");
      GridFS fs = new GridFS(db);
      GridFSDBFile gridFSDBFile = fs.findOne(new ObjectId(fileId));
      OutputStream sos = response.getOutputStream();
      response.setContentType("application/octet-stream");
      // 獲取原文件名
      String name = (String) gridFSDBFile.get("filename");
      String fileName = new String(name.getBytes("GBK"), "ISO8859-1");
      // 設(shè)置下載文件名
      response.addHeader("Content-Disposition", "attachment; filename=\"" + fileName + "\"");
      // 向客戶端輸出文件
      gridFSDBFile.writeTo(sos);
      sos.flush();
      sos.close();
    } catch (IOException e) {
      e.printStackTrace();
    }
  }