Question

I’m trying to serve an image in my application as a java.awt.BufferedImage object. When I attempt to perform a GET, here are the results:

• Accept:image/jpeg renders a valid picture
• Accept:*/* returns an HTTP 406

Here is the relevant part of my servlet-context.xml:

    <beans:bean id="messageAdapter"
    class="org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter">
    <beans:property name="order" value="1" />
    <beans:property name="messageConverters">
        <beans:array>
            <beans:bean class="org.springframework.http.converter.BufferedImageHttpMessageConverter"/>
        </beans:array>
    </beans:property>

</beans:bean>

And here is my Controller:

    @RequestMapping(value = "photo/{photoId:[0-9]+}", method = RequestMethod.GET, produces = MediaType.IMAGE_JPEG_VALUE)
    @ResponseBody
    public BufferedImage getPhoto(
        @PathVariable long photoId) {
        return photoService.getPhoto(photoId);
    }

MediaType.IMAGE_JPEG_VALUE is “image/jpeg”. It is my understanding that an accept header of */* would never generate a HTTP 406, which according to this page tells us that the caller doesn’t accept content of that type.

This is an issue because most browsers have “*/*” in their accept headers, and would not be able to view this image unless the user hard-coded the accept header.

Am I missing something here?

Thanks in advance.

Answer 1

Message converters are picky about the Accept header, and they have to be since they are applied to all handlers annotated with @ResponseBody.

A couple of ways you can get around this:

Option 1: Extend the BufferedImageHttpMessageConverter to handle */* as well, NOTE: this can have unintended consequences if you add other message-converters later on as all of a sudden, handlers you want to produce JSON starts producing images instead.

public class ExtendedBufferedImageHttpMessageConverter extends BufferedImageHttpMessageConverter {

    @Override
    public boolean canWrite(Class<?> clazz, MediaType mediaType) {
    if (mediaType.equals(MediaType.ALL)) {
        return super.canWrite(clazz, MediaType.IMAGE_JPEG);
    } else {
        return super.canWrite(clazz, mediaType);
    }
}

Then use this instead of the normal BufferedImageHttpMessageConverter in your spring config.

Option 2: Create a filter or interceptor that is applied to your image requests and wrap the request in such a way the Accept header looks like image/jpeg instead of */*. This will “trick” spring into thinking that the client accepts jpeg and trigger the BufferedImageHttpMessageConverter.