• 使用 ResponseEntity 返回結果，設定HttpHeader中的content-type，如：image/png

    @RequestMapping(method = RequestMethod.GET)
    public ResponseEntity getFile(@RequestParam long id) {
        Result result = fileService.getFile(id);
        if (result.getCode() == 1) {
            MediaType mediaType = MediaType.parseMediaType(result.getMsg());
            HttpHeaders headers = new HttpHeaders();
            headers.setContentType(mediaType);
            ResponseEntity e = new ResponseEntity(result.getData(), headers, HttpStatus.OK);
            return e;
        }
        return ResponseEntity.status(404).body(result.getMsg());
    }
 

• 第二種方法：在@RequestMapping中加上 produces 來設定圖片型別, 不需要單獨設定HttpHeaders

@RequestMapping(method = RequestMethod.GET, produces = "image/png")