Logging with Retrofit 2

Here is an Interceptor that logs both the request and response bodies (using Timber, based on an example from the OkHttp docs and some other SO answers):

public class TimberLoggingInterceptor implements Interceptor {
    @Override
    public Response intercept(Chain chain) throws IOException {
        Request request = chain.request();

        long t1 = System.nanoTime();
        Timber.i("Sending request %s on %s%n%s", request.url(), chain.connection(), request.headers());
        Timber.v("REQUEST BODY BEGIN\n%s\nREQUEST BODY END", bodyToString(request));

        Response response = chain.proceed(request);

        ResponseBody responseBody = response.body();
        String responseBodyString = response.body().string();

        // now we have extracted the response body but in the process
        // we have consumed the original reponse and can't read it again
        // so we need to build a new one to return from this method

        Response newResponse = response.newBuilder().body(ResponseBody.create(responseBody.contentType(), responseBodyString.getBytes())).build();

        long t2 = System.nanoTime();
        Timber.i("Received response for %s in %.1fms%n%s", response.request().url(), (t2 - t1) / 1e6d, response.headers());
        Timber.v("RESPONSE BODY BEGIN:\n%s\nRESPONSE BODY END", responseBodyString);

        return newResponse;
    }

    private static String bodyToString(final Request request){

        try {
            final Request copy = request.newBuilder().build();
            final Buffer buffer = new Buffer();
            copy.body().writeTo(buffer);
            return buffer.readUtf8();
        } catch (final IOException e) {
            return "did not work";
        }
    }
}

I met the thing as you and I tried to ask the author of the book Retrofit: Love working with APIs on Android (here is the link) (nope! I am not making some ads for them....but they are really nice guys :) And the author replied to me very soon, with both Log method on Retrofit 1.9 and Retrofit 2.0-beta.

And here is the code of Retrofit 2.0-beta:

HttpLoggingInterceptor logging = new HttpLoggingInterceptor();  
// set your desired log level
logging.setLevel(Level.BODY);

OkHttpClient httpClient = new OkHttpClient();  
// add your other interceptors …

// add logging as last interceptor
httpClient.interceptors().add(logging);  // <-- this is the important line!

Retrofit retrofit = new Retrofit.Builder()  
   .baseUrl(API_BASE_URL)
   .addConverterFactory(GsonConverterFactory.create())
   .client(httpClient)
   .build();

This is how to add logging method with the help of HttpLoggingInterceptor. Also if you are the reader of that book I mentioned above, you may find that it says there is not log method with Retrofit 2.0 anymore -- which, I had asked the author, is not correct and they will update the book next year talking about it.

// In case you are not that familiar with the Log method in Retrofit, I would like to share something more.

Also should be noticed that there are some Logging Levels you could pick. I use the Level.BODY most of the time, which will give some thing like this:

You can find almost all the http staff inside the picture: the header, the content and response, etc.

And sometimes you really don't need all the guests to attend your party: I just want to know whether it's successfully connected, that internet call is successfully made within my Activiy & Fragmetn. Then you are free to use Level.BASIC, which will return something like this:

Can you find the status code 200 OK inside? That is it :)

Also there is another one, Level.HEADERS, which will only return the header of the network. Ya of course another picture here:

That's all of the Logging trick ;)

And I would like to share you with the tutorial I learned a lot there. They have a bunch of great post talking about almost everything related to Retrofit, and they are continuing updating the post, at the same time Retrofit 2.0 is coming. Please take a look at those work, which I think will save you lots of time.

In Retrofit 2 you should use HttpLoggingInterceptor.

Add dependency to build.gradle. Latest version as of October 2019 is:

implementation 'com.squareup.okhttp3:logging-interceptor:4.2.1'

Create a Retrofit object like the following:

HttpLoggingInterceptor interceptor = new HttpLoggingInterceptor();
interceptor.setLevel(HttpLoggingInterceptor.Level.BODY);
OkHttpClient client = new OkHttpClient.Builder().addInterceptor(interceptor).build();

Retrofit retrofit = new Retrofit.Builder()
        .baseUrl("https://backend.example.com")
        .client(client)
        .addConverterFactory(GsonConverterFactory.create())
        .build();

return retrofit.create(ApiClient.class);

In case of deprecation warnings, simply change setLevel to:

interceptor.level(HttpLoggingInterceptor.Level.BODY);

The above solution gives you logcat messages very similar to the old ones set by

setLogLevel(RestAdapter.LogLevel.FULL)

In case of java.lang.ClassNotFoundException:

Older Retrofit version might require an older logging-interceptor version. Take a look at comments sections for details.

The main problem which I faced was dynamical adding headers and logging them into debug logcat. I've tried to add two interceptors. One for logging and one for adding headers on-the-go (token authorization). The problem was that we may .addInterceptor or .addNetworkInterceptor. As Jake Wharton said to me: "Network interceptors always come after application interceptors. See https://github.com/square/okhttp/wiki/Interceptors". So here is working example with headers and logs:

OkHttpClient httpClient = new OkHttpClient.Builder()
            //here we can add Interceptor for dynamical adding headers
            .addNetworkInterceptor(new Interceptor() {
                @Override
                public Response intercept(Chain chain) throws IOException {
                    Request request = chain.request().newBuilder().addHeader("test", "test").build();
                    return chain.proceed(request);
                }
            })
            //here we adding Interceptor for full level logging
            .addNetworkInterceptor(new HttpLoggingInterceptor().setLevel(HttpLoggingInterceptor.Level.BODY))
            .build();

    Retrofit retrofit = new Retrofit.Builder()
            .addConverterFactory(GsonConverterFactory.create(gsonBuilder.create()))
            .addCallAdapterFactory(RxJavaCallAdapterFactory.create())
            .client(httpClient)
            .baseUrl(AppConstants.SERVER_ADDRESS)
            .build();