How to force a cached or network response on Android with Retrofit + OkHttp

ForceCacheOrNetwork.java

OkHttpClient okHttpClient = new OkHttpClient();
try {
    int cacheSize = 10 * 1024 * 1024  // 10 MiB
    Cache cache = new Cache(getCacheDir(), cacheSize);
    okHttpClient.setCache(cache);
} catch (IOException e) {
    Log.e(TAG, "Could not set cache", e);
}

// Forces cache. Used for cache connection
RequestInterceptor cacheInterceptor = new RequestInterceptor() {
    @Override
    public void intercept(RequestFacade request) {
        request.addHeader("Cache-Control", "only-if-cached, max-stale=" + Integer.MAX_VALUE);
    }
};

// Skips cache and forces full refresh. Used for service connection
RequestInterceptor noCacheInterceptor = new RequestInterceptor() {
    @Override
    public void intercept(RequestFacade request) {
        request.addHeader("Cache-Control", "no-cache");
    }
};

// Build service connections
RestAdapter.Builder builder = new RestAdapter.Builder()
        .setEndpoint("http://yourserviceurl.com")
        .setClient(new OkClient(okHttpClient))
                // process request in the order they are called (e.g. cache first then service)
        .setExecutors(Executors.newSingleThreadExecutor(), new MainThreadExecutor());
        .setRequestInterceptor(noCacheInterceptor)
ServiceConnection serviceConnection = builder.build().create(ServiceConnection.class);

builder.setRequestInterceptor(cacheInterceptor);
ServiceConnection cacheConnection = builder.build().create(ServiceConnection.class);

/*
Now you can use the cacheConnection to show the user cached results immediately and 
then try to receive network results using the serviceConnection. 
*/