What is the correct way to serve image file from Blob in Spring MVC controller?

Question

I wrote a simple SpringMVC app and host on a Paas. I have created a table in Mysql and a column is the Blob. I can upload files through the Mysql admin. Right now, my server can serve html file or javascript files correctly in browser. However, when I serve a jpg file in http://myserver.com/File/ad.jpg, my browser showed a small icon and if I save it, the Windows Image software shows that the image is damaged.

Here are some of the code:

@RequestMapping(value="/File/**", //{name:.+}", 
    method = RequestMethod.GET)
public @ResponseBody void getContent(
//  @PathVariable("name") String name,
    HttpServletRequest request, 
    HttpServletResponse response) throws IOException {
    String name =   request.getPathInfo();
    ....
    IOUtils.copy(blob.getBinaryStream(), out);

I found that getServletContext() returns null, so I wasn't able to get contentType, so I saved contentType in Mysql as image/jpeg for the ad.jpg. I set the disposition to be inline. What else should I do to serve a jpg?

Try returning a `byte[]`. Never write directly to the output streams from a Spring MVC controller. — chrylis -cautiouslyoptimistic-, Sep 13 '14 at 19:59
@chrylis I set the contentType to be image/jpeg, and used write(blob.getBytes(0, length)), but now I got an empty page for ad.jpg — Splash, Sep 13 '14 at 21:00
What part of "don't write to the output stream" wasn't clear? — chrylis -cautiouslyoptimistic-, Sep 13 '14 at 21:30
@chrylis, I misunderstood, I thought not to use inputstream. So are you saying the void getContent() function should return a byte[]? BTW, the [solution](http://stackoverflow.com/questions/5673260/downloading-a-file-from-spring-controllers) to a similar problem is using outputStream but mine doesn't work for a jpg file — Splash, Sep 13 '14 at 22:06
@Bart, I am setting contentType using image/jpeg, is it good? — Splash, Sep 13 '14 at 22:11
That answer is more than three years old and completely out of date. — chrylis -cautiouslyoptimistic-, Sep 13 '14 at 22:21
@Splash -- You could do it the way shown in the link, but you'd have to remove your `@ResponseBody` annotation. — Dave L., Sep 14 '14 at 01:34
@chrylis, I tried return HttpEntity with the getBytes(1, length), same result of 55.5KB damaged file as the previous write byte to outputstream. Problem could exist somewhere else? — Splash, Sep 14 '14 at 17:44

score 1 · Accepted Answer · answered Sep 14 '14 at 23:39

I finally found that the original code has nothing wrong. The original Mysql admin web page uploaded the blob incorrectly. After I found the Paas has a secret new admin page and that can upload a correct blob with an binary option. I still appreciate all the replies in comments.

What is the correct way to serve image file from Blob in Spring MVC controller?

1 Answers1