How to return an image in Spring Boot controller and serve like a file system

Question

I've tried the various ways given in Stackoverflow, maybe I missed something.

I have an Android client (whose code I can't change) which is currently getting an image like this:

HttpURLConnection connection = (HttpURLConnection) url.openConnection();
connection.setRequestMethod("GET");
connection.connect();

Where url is the location of the image (static resource on CDN). Now my Spring Boot API endpoint needs to behave like a file resource in the same way so that the same code can get images from the API (Spring boot version 1.3.3).

So I have this:

@ResponseBody
@RequestMapping(value = "/Image/{id:.+}", method = RequestMethod.GET, consumes = MediaType.ALL_VALUE, produces = MediaType.IMAGE_JPEG_VALUE)
public ResponseEntity<byte[]> getImage(@PathVariable("id")String id) {
    byte[] image = imageService.getImage(id);  //this just gets the data from a database
    return ResponseEntity.ok(image);
}

Now when the Android code tries to get http://someurl/image1.jpg I get this error in my logs:

Resolving exception from handler [public org.springframework.http.ResponseEntity com.myproject.MyController.getImage(java.lang.String)]: org.springframework.web.HttpMediaTypeNotAcceptableException: Could not find acceptable representation

Same error happens when I plug http://someurl/image1.jpg into a browser.

Oddly enough my tests check out ok:

Response response = given()
            .pathParam("id", "image1.jpg")
            .when()
            .get("MyController/Image/{id}");

assertEquals(HttpStatus.OK.value(), response.getStatusCode());
byte[] array = response.asByteArray(); //byte array is identical to test image

How do I get this to behave like an image being served up in the normal way? (Note I can't change the content-type header that the android code is sending)

EDIT

Code after comments (set content type, take out produces):

@RequestMapping(value = "/Image/{id:.+}", method = RequestMethod.GET, consumes = MediaType.ALL_VALUE)
public ResponseEntity<byte[]> getImage(@PathVariable("id")String id, HttpServletResponse response) {
    byte[] image = imageService.getImage(id);  //this just gets the data from a database
    response.setContentType(MediaType.IMAGE_JPEG_VALUE);
    return ResponseEntity.ok(image);
}

In a browser this just seems to give a stringified junk (byte to chars i guess). In Android it doesn't error, but the image doesn't show.

What does the client send as its Accept header? What happens when you remove the produces attribute, and just specify the content type in the response? — JB Nizet, Nov 11 '16 at 23:30
@JBNizet the Accept header is whatever the default is for HttpURLConnection (Android SDK). It's definitely not specifically set. I tried omitting `produces` but that seems to deliver plain text (in a browser). Setting content-type is same as `produces` anyway, no? — Manish Patel, Nov 12 '16 at 20:45
@JBNizet I tried setting the content type explicitly too, I get the same error in the log — Manish Patel, Nov 12 '16 at 21:15
this well prepared video tutorial step by step guide, to how to read image from spring boot backend, in hear front end working on Angular. — Manjitha Teshara, Apr 28 '20 at 17:28

score 24 · Answer 1 · answered Nov 18 '16 at 22:06

24

I believe this should work:

@RequestMapping(value = "/Image/{id:.+}", method = RequestMethod.GET)
public ResponseEntity<byte[]> getImage(@PathVariable("id") String id) {
    byte[] image = imageService.getImage(id);
    return ResponseEntity.ok().contentType(MediaType.IMAGE_JPEG).body(image);
}

Notice that the content-type is set for ResponseEntity, not for HttpServletResponse directly.

answered Nov 18 '16 at 22:06

Roman

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thanks, i did actually try this permutation but it did not work for me – Manish Patel Nov 21 '16 at 09:03
@user2393012 Strange, because I checked and it works for me. Did you notice I also removed `consumes`, `produces` and `@ResponseBody`? And what error did you get with this code? – Roman Nov 21 '16 at 11:59
1

yes, noticed the omissions. I didn't get any error actually, in the browser it just appeared as a empty frame – Manish Patel Nov 21 '16 at 12:28
@user2393012 Did you check the response headers? Empty frame could be an empty image. – Roman Nov 21 '16 at 12:33
no but the image from the database hasn't been touched - on Spring side i do output the `byte[]` length and it's fairly sizeable – Manish Patel Nov 21 '16 at 12:39
@user2393012 There is also a possibility that the request was handled by some other controller method. – Roman Nov 21 '16 at 12:45

score 12 · Accepted Answer · answered Nov 14 '16 at 09:50

Finally fixed this... I had to add a ByteArrayHttpMessageConverter to my WebMvcConfigurerAdapter subclass:

@Override
public void configureMessageConverters(List<HttpMessageConverter<?>> converters) {
    final ByteArrayHttpMessageConverter arrayHttpMessageConverter = new ByteArrayHttpMessageConverter();
    final List<MediaType> list = new ArrayList<>();
    list.add(MediaType.IMAGE_JPEG);
    list.add(MediaType.APPLICATION_OCTET_STREAM);
    arrayHttpMessageConverter.setSupportedMediaTypes(list);
    converters.add(arrayHttpMessageConverter);

    super.configureMessageConverters(converters);
}

this answer seems incomplete. Do you have a complete solution that looks like @Roman's answer? — Robert Beltran, Jul 18 '17 at 16:36

mavriksc · Answer 3 · 2019-03-27T16:46:40.367

8

In case you don't know the file/mime type you can do this.... I've done this where i take an uploaded file and replace the file name with a guid and no extension and browsers / smart phones are able to load the image no issues. the second is to serve a file to be downloaded.

@RestController
@RequestMapping("img")
public class ImageController {

@GetMapping("showme")
public ResponseEntity<byte[]> getImage() throws IOException{
    File img = new File("src/main/resources/static/test.jpg");
    return ResponseEntity.ok().contentType(MediaType.valueOf(FileTypeMap.getDefaultFileTypeMap().getContentType(img))).body(Files.readAllBytes(img.toPath()));
}
@GetMapping("thing")
public ResponseEntity<byte[]> what() throws IOException{
    File file = new File("src/main/resources/static/thing.pdf");
    return ResponseEntity.ok()
            .header("Content-Disposition", "attachment; filename=" +file.getName())
            .contentType(MediaType.valueOf(FileTypeMap.getDefaultFileTypeMap().getContentType(file)))
            .body(Files.readAllBytes(file.toPath()));
}


}

UPDATE in java 9+ you need to add compile 'com.sun.activation:javax.activation:1.2.0' to your dependencies this has also been moved or picked up by jakarta.see this post

edited Mar 27 '19 at 16:46

answered Jun 28 '17 at 22:04

mavriksc

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For some files (apple pass/wallet ) to work properly you have to include content length. – mavriksc Jun 29 '17 at 14:41
Thank you, `getImage()` method worked for me. But I had a `java.lang.ClassNotFoundException: com.sun.activation.registries.LogSupport` while setting `contentType()`. Finally I just used `contentType(MediaType.IMAGE_JPEG)` instead of dynamic content type creation and exception is gone. My way works not only for JPEG, but also for PNG. – Yamashiro Rion Mar 25 '19 at 12:30
i think this is an issue with java 9+. i may take a look at how to keep it dynamic and post an update. – mavriksc Mar 26 '19 at 17:20
Yes, you are right, I use Java 10. I hope you'll find a way. :) – Yamashiro Rion Mar 27 '19 at 06:31
2

Thank you, I have checked this solution and it really works! – Yamashiro Rion Mar 28 '19 at 05:15

score 0 · Answer 4 · answered Mar 28 '19 at 21:55

Using Apache Commons, you can do this and expose the image on an endpoint

@RequestMapping(value = "/image/{imageid}",method= RequestMethod.GET,produces = MediaType.IMAGE_JPEG_VALUE)
public @ResponseBody byte[] getImageWithMediaType(@PathVariable int imageid) throws IOException {
    InputStream in = new ByteArrayInputStream(getImage(imageid));
    return IOUtils.toByteArray(in);
    }

All images will be served at endpoint /image/{imageid}

How to return an image in Spring Boot controller and serve like a file system

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