Jersey REST service to return both jpeg and png images

Question

I am trying to have a single Jersey REST service that could return an image of either a jpeg type or a png type , the reason is because the service only has access to and is returning binary data and cannot tell if its a jpeg image or a png image .

If I use the following declaration the browser displays binary data .

@Produces("image/*")

However if I use the following for jpeg images the correct image is displayed.

@Produces("image/jpeg").

I want to know how I could use a single declaration that would make the browser identify the right type of image(jpeg or png) to be rendered?

Answer 1

According to JAX-RS specification it is allowed to list multiple media types:

@Produces({"image/png", "image/jpeg", "image/gif"})

see: https://jax-rs-spec.java.net/nonav/2.0/apidocs/javax/ws/rs/Produces.html

Update: for more details see @forty-two 's answer too.

Answer 2

If the service doesn't know the type, it cannot be any more specific than image/*. But, you could inspect the first few bytes of the data to detect the type and add Content-Type header accordingly.

Note that the purpose for having more than one @Produces annotation is for content negotiation, where the user agent express the wanted resource representation and the server answers with an appropriate variant of the data, e.g. JPEG or PNG.