Retrofit 2 - Elegant way of adding headers in the api level

Question

My Retrofit 2 (2.0.2 currently) client needs to add custom headers to requests.

I\'m using an Interceptor to add these headers to all request

Answer 1

I came up with a very simple and elegant (in my opinion) solution to my problem, and probably for other scenarios.

I use the Headers annotation to pass my custom annotations, and since OkHttp requires that they follow the Name: Value format, I decided that my format will be: @: ANNOTATION_NAME.

So basically:

public interface MyApi {
    @POST("register")
    @HEADERS("@: NoAuth")
    Call register(@Body RegisterRequest data);

    @GET("user/{userId}")
    Call getUser(@Path("userId") String userId);
}

Then I can intercept the request, check whether I have an annotation with name @. If so, I get the value and remove the header from the request.
This works well even if you want to have more than one "custom annotation":

@HEADERS({
    "@: NoAuth",
    "@: LogResponseCode"
})

Here's how to extract all of these "custom annotations" and remove them from the request:

new OkHttpClient.Builder().addNetworkInterceptor(new Interceptor() {
    @Override
    public okhttp3.Response intercept(Chain chain) throws IOException {
        Request request = chain.request();

        List customAnnotations = request.headers().values("@");

        // do something with the "custom annotations"

        request = request.newBuilder().removeHeader("@").build();
        return chain.proceed(request);
    }
});