GzipRequestInterceptor.java

package org.edx.mobile.http;

import java.io.IOException;

import okhttp3.Interceptor;
import okhttp3.MediaType;
import okhttp3.Request;
import okhttp3.RequestBody;
import okhttp3.Response;
import okio.BufferedSink;
import okio.GzipSink;
import okio.Okio;

/**
 * This interceptor compresses the HTTP request body. Many webservers can't handle this!
 * https://github.com/square/okhttp/wiki/Interceptors
 **/
public final class GzipRequestInterceptor implements Interceptor {
    @Override public Response intercept(Chain chain) throws IOException {
        Request originalRequest = chain.request();
        if (originalRequest.body() == null || originalRequest.header("Content-Encoding") != null) {
            return chain.proceed(originalRequest);
        }

        Request compressedRequest = originalRequest.newBuilder()
            .header("Content-Encoding", "gzip")
            .method(originalRequest.method(), gzip(originalRequest.body()))
            .build();
        return chain.proceed(compressedRequest);
    }

    private RequestBody gzip(final RequestBody body) {
        return new RequestBody() {
            @Override public MediaType contentType() {
                return body.contentType();
            }

            @Override public long contentLength() {
                return -1; // We don't know the compressed length in advance!
            }

            @Override public void writeTo(BufferedSink sink) throws IOException {
                BufferedSink gzipSink = Okio.buffer(new GzipSink(sink));
                body.writeTo(gzipSink);
                gzipSink.close();
            }
        };
    }
}