下载时如何设置文件类型？

Question

I have this Spring endpoint which returns file:

@RequestMapping(value = "/files/{merchant_id}", method = RequestMethod.GET)
    public void getFile(@PathVariable("merchant_id") Integer merchant_id, HttpServletResponse response) {

        try {
          File initialFile = new File("/opt/1/Why_Brookfield_Callout_3x.png");
          InputStream is = FileUtils.openInputStream(initialFile);
          org.apache.commons.io.IOUtils.copy(is, response.getOutputStream());
          response.flushBuffer();
        } catch (IOException ex) {
          throw new RuntimeException("IOError writing file to output stream");
        }
    }

But when I download the file I get type text. How I can set the type of there file to .png file?

Answer 1

add produces = MediaType.IMAGE_PNG in your @RequestMapping

see https://docs.spring.io/spring/docs/current/javadoc-api/org/springframework/http/MediaType.html for more mediatypes

So the method definition becomes:

@RequestMapping(value = "/files/{merchant_id}", method = RequestMethod.GET, produces = org.springframework.http.MediaType.IMAGE_PNG)