1

I have this endpoint:

@GetMapping("/thumbnail/{imageName}")
@PreAuthorize("hasRole('BASIC')")
public ResponseEntity<InputStreamResource> natalChartThumbnail() throws IOException {

    ByteArrayOutputStream os = new ByteArrayOutputStream();

    // 🔹 Generate thumbnail
    BufferedImage bufferedImage = Thumbnails.of(new File("/usr/local/bin/tmp/scaled_sun_in_cancer_moon_in_aquarius.jpg"))
            .scale(1.0)
            .asBufferedImage();

    ImageIO.write(bufferedImage, "jpg", os);
    InputStream is = new ByteArrayInputStream(os.toByteArray());

    return ResponseEntity.ok()
            .contentType(MediaType.parseMediaType("image/jpg"))
            .body(new InputStreamResource(is));

}

But in Postman, I see this:

enter image description here

and imageExtension: jpg

I also tried with:

 return ResponseEntity.ok()
                .contentType(MediaType.parseMediaType("image/jpeg"))
                .body(new InputStreamResource(is));

with the same result

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5
  • 2
    Did you check the received Content-Type? Commented Mar 8, 2025 at 11:56
  • 2
    Your edit with image/jpeg is equivalent to the answer that suggests setting the produces attribute of the @GetMapping annotation. Are you sure it didn't work? As ^^ Olivier asks, what did you receive as a content-type response header? Commented Mar 14, 2025 at 13:42
  • 1
    Also, you don't need to parse that string. There's a MediaType constant for it already, in MediaType.IMAGE_JPEG. Commented Mar 14, 2025 at 13:45
  • 1
    Agree with @SotiriosDelimanolis. Setting the Content-Type using produces or contentType leads to the same result. The issue persisted even after applying Olivier’s suggestion due to Postman caching. I've managed to reproduce it. And I guess you can as well Commented Mar 14, 2025 at 13:53
  • This question is linked on meta Commented Mar 25, 2025 at 13:21

3 Answers 3

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4
How to resolve the issue

The following 2 steps have to resolve your issue:

  1. Set the correct Content-Type by contentType(MediaType.IMAGE_JPEG)
  2. Make Postman to forget incorrect Content-Type.
    Perform any of the following. No need to do all of them:
    • run Clear Response enter image description here
    • run Menu Bar -> Help -> Clear Cache and Reload enter image description here
    • make a request in a new tab in Postman
    • completely close and open Postman
Why is setting the correct header not enough?

The issue persists after just changing Content-Type due to Postman caching.
There were similar GitHub issues:

How to reproduce the problem and fix:
  1. Set incorrect Content-Type (image/jpg), the preview fails
  2. Set correct Content-Type (image/jpeg), the preview still fails
  3. Open a new tab in Postman and make the same request, the preview successfully displays the requested picture
Additional notes:

The SO question regarding the correct header - Is the MIME type 'image/jpg' the same as 'image/jpeg'?.

To set the header Content-Type: image/jpeg, you can use any of the following options, as they all lead to the same result:

  • ResponseEntity.ok().contentType(MediaType.parseMediaType("image/jpeg"))
  • ResponseEntity.ok().contentType(MediaType.IMAGE_JPEG)
  • Setting produces = MediaType.IMAGE_JPEG_VALUE in an annotation for mapping HTTP requests

You can test this by looking to returned headers using:

curl -i http://localhost:8080/thumbnail/imageName
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Comments

2
+300

I found the issue. You didn't try this option given below:

produces = MediaType.IMAGE_JPEG_VALUE

Please try the above option. I have cleaned up your code a little bit. So, modify your code based on the code given below:

package com.example;

import java.awt.image.BufferedImage;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.IOException;
import java.io.InputStream;

import javax.imageio.ImageIO;

import org.springframework.core.io.InputStreamResource;
import org.springframework.http.MediaType;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RestController;

import net.coobird.thumbnailator.Thumbnails;

@RestController
public class SampleController {
    
    @GetMapping(value = "/thumbnail/{imageName}", produces = MediaType.IMAGE_JPEG_VALUE)
    public ResponseEntity<InputStreamResource> natalChartThumbnail(@PathVariable String imageName) throws IOException {

        ByteArrayOutputStream os = new ByteArrayOutputStream();

        // 🔹 Generate thumbnail
        BufferedImage bufferedImage = Thumbnails.of(new File("/Users/anisb/" + imageName + ".jpg"))
                .scale(1.0)
                .asBufferedImage();

        ImageIO.write(bufferedImage, "jpg", os);
        InputStream in = new ByteArrayInputStream(os.toByteArray());

        return ResponseEntity.ok().body(new InputStreamResource(in));

    }
}

This works.

Postman Screenshot:

enter image description here

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Comments

2

Did you try to change image/jpg to image/jpeg. image/jpg is not a valid Content-Type.

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