Okhttp 3 example in Android

The following code demonstrates using Okhttp 3 in Android for making network calls with username and password, Bearer token or without any credential.

1. Add the internet use permission in the manifest file.

<uses-permission android:name="android.permission.INTERNET"/>

2. Add the okhttp 3 dependencies in the gradle file, the second one is for logging.

compile 'com.squareup.okhttp3:okhttp:3.5.0'
compile 'com.squareup.okhttp3:logging-interceptor:3.5.0'

3. Create the network service interface, NetworkInterface.java

public interface NetworkInterface {
    /**
     * Get string by username password
     * @param endpoint rest url
     * @param username username
     * @param password password
     * @return String
     */
    String getString(String endpoint, String username, String password);


    /**
     * Get string by bear token
     * @param endpoint rest url
     * @param token bearer token
     * @return String
     */
    String getString(String endpoint, String token);

    /**
     * Search call
     * @param query search query
     * @return String
     */
    String search(String query);
}

4. The okhttp 3 network service implementation, NetworkService.java

import android.net.Uri;
import android.util.Base64;
import android.util.Log;

import java.io.IOException;
import java.net.MalformedURLException;
import java.net.SocketTimeoutException;
import java.net.URL;
import java.net.UnknownHostException;
import java.util.concurrent.TimeUnit;

import okhttp3.Interceptor;
import okhttp3.OkHttpClient;
import okhttp3.Request;
import okhttp3.Response;
import okhttp3.logging.HttpLoggingInterceptor;

public enum NetworkService implements NetworkInterface {
    INSTANCE;

    private static final long CONNECT_TIMEOUT = 20000;   // 2 seconds
    private static final long READ_TIMEOUT = 20000;      // 2 seconds
    private static OkHttpClient okHttpClient = null;
    private static final String SEARCH_URL = "https://api.myjson.com/bins/hoh4j/";


    /**
     * Method to build and return an OkHttpClient so we can set/get
     * headers quickly and efficiently.
     * @return OkHttpClient
     */
    private OkHttpClient buildClient() {
        if (okHttpClient != null) return okHttpClient;

        OkHttpClient.Builder okHttpClientBuilder = new OkHttpClient.Builder()
                .connectTimeout(CONNECT_TIMEOUT, TimeUnit.MILLISECONDS)
                .readTimeout(READ_TIMEOUT, TimeUnit.MILLISECONDS);

        // Logging interceptor
        HttpLoggingInterceptor httpLoggingInterceptor = new HttpLoggingInterceptor();
        httpLoggingInterceptor.setLevel(HttpLoggingInterceptor.Level.BODY);
        okHttpClientBuilder.addInterceptor(httpLoggingInterceptor);

        // custom interceptor for adding header and NetworkMonitor sliding window
        okHttpClientBuilder.addInterceptor(new Interceptor() {
            @Override
            public Response intercept(Chain chain) throws IOException {
                // Add whatever we want to our request headers.
                Request request = chain.request().newBuilder().addHeader("Accept", "application/json").build();
                Response response;
                try {
                    response = chain.proceed(request);
                } catch (SocketTimeoutException | UnknownHostException e) {
                    e.printStackTrace();
                    throw new IOException(e);
                }
                return response;
            }
        });

        return  okHttpClientBuilder.build();
    }

    private Request.Builder buildRequest(URL url) {
        return new Request.Builder()
                .url(url);
    }

    private Request.Builder buildRequest(URL url, String credential) {
        return buildRequest(url).header("Authorization", credential);
    }

    private URL buildURL(Uri builtUrl) {
        if (builtUrl == null) return null;
        try {
            String urlStr = builtUrl.toString();
            return new URL(urlStr);
        } catch (MalformedURLException e) {
            e.printStackTrace();
            return null;
        }
    }

    private URL buildURL(String url) {
        try {
            return new URL(url);
        } catch (MalformedURLException e) {
            e.printStackTrace();
            return null;
        }
    }

    private String getData(Request request) {
        OkHttpClient client = buildClient();
        try {
            Response response = client.newCall(request).execute();
            return response.body().string();
        } catch (IOException e) {
            e.printStackTrace();
            return null;
        }
    }


    @Override
    public String getString(String endpoint, String username, String password) {
        Log.d("NetworkService", "getString by username and password from " + endpoint);
        String credentials = username + ":" + password;
        final String basicAuth = "Basic " + Base64.encodeToString(credentials.getBytes(), Base64.NO_WRAP);

        Request request = buildRequest(buildURL(endpoint), basicAuth).build();
        return getData(request);
    }

    @Override
    public String getString(String endpoint, String token) {
        Log.d("NetworkService", "getString by Bearer token from " + endpoint);
        String credentials = "Bearer " + token;
        Request request = buildRequest(buildURL(endpoint), credentials).build();
        return getData(request);
    }

    @Override
    public String search(String query) {
        Uri uri = Uri.parse(SEARCH_URL)
                .buildUpon()
                .appendQueryParameter("name", query)
                .appendQueryParameter("category", "student")
                .build();
        URL url = buildURL(uri);

        Log.d("NetworkService","built search url: " + url.toString());

        Request request = buildRequest(url).build();

        return getData(request);
    }

}

5. Use it on a background thread.

public class MainActivity extends AppCompatActivity {
    TextView tvDisplay;
    Handler mHandler = new Handler();
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        tvDisplay = (TextView) findViewById(R.id.tv_display);
    }

    public void apiCall(View v) {
        new Thread(new Runnable() {
            @Override
            public void run() {
                searchCall();
            }
        }).start();
    }

    private void searchCall() {
        final String data = NetworkService.INSTANCE.search("hello");
        mHandler.post(new Runnable() {
            @Override
            public void run() {
                tvDisplay.setText(data);
            }
        });
    }
}

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