OkHttp Android

Initially Android had only two HTTP clients: HttpURLConnection and Apache HTTP Client; for sending and receiving data from the web. Each of these clients required a lot of boilerplate code to be written inside the AsyncTask or the background thread methods. Moreover, these clients have their own sets of limitations when it came to cancelling an HTTP request or connection-pooling.

OkHttp Android Advantages

1. Connection pooling
2. Gziping
3. Caching
4. Recovering from network problems
5. Redirects
6. Retries
7. Support for synchronous and asynchronous calls

Synchronous vs Asynchronous calls

• Synchronous calls require an AsyncTask wrapper around it. That means it doesn’t support cancelling a request. Also, AsyncTasks generally leak the Activity’s context, which is not preferred.
• Asynchronous Calling is the recommneded way since it supports native cancelling, tagging multiple requests and canceling them all with a single method call (by invoking the cancel on the Acitivty instance inside the onPause or onDestroy method).

compile 'com.squareup.okhttp3:okhttp:3.4.1'

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

OkHttp Android Example Code

package com.neo-istone.okhttp;

import android.os.AsyncTask;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;

import org.json.JSONException;
import org.json.JSONObject;

import java.io.IOException;

import okhttp3.Call;
import okhttp3.Callback;
import okhttp3.MediaType;
import okhttp3.OkHttpClient;
import okhttp3.Request;
import okhttp3.RequestBody;
import okhttp3.Response;

public class MainActivity extends AppCompatActivity {

    OkHttpClient client = new OkHttpClient();

    TextView txtString;

    public String url= "https://reqres.in/api/users/2";


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        txtString= (TextView)findViewById(R.id.txtString);

        OkHttpHandler okHttpHandler= new OkHttpHandler();
        okHttpHandler.execute(url);
    }

    public class OkHttpHandler extends AsyncTask {

        OkHttpClient client = new OkHttpClient();

        @Override
        protected String doInBackground(String...params) {

            Request.Builder builder = new Request.Builder();
            builder.url(params[0]);
            Request request = builder.build();

            try {
                Response response = client.newCall(request).execute();
                return response.body().string();
            }catch (Exception e){
                e.printStackTrace();
            }
            return null;
        }

        @Override
        protected void onPostExecute(String s) {
            super.onPostExecute(s);
            txtString.setText(s);
        }
    }

}

package com.neo-istone.okhttp;

import android.os.AsyncTask;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;

import org.json.JSONException;
import org.json.JSONObject;

import java.io.IOException;

import okhttp3.Call;
import okhttp3.Callback;
import okhttp3.MediaType;
import okhttp3.OkHttpClient;
import okhttp3.Request;
import okhttp3.RequestBody;
import okhttp3.Response;

public class MainActivity extends AppCompatActivity {
    
    TextView txtString;
    public String url= "https://reqres.in/api/users/2";

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        txtString= (TextView)findViewById(R.id.txtString);

        try {
            run();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    void run() throws IOException {

        OkHttpClient client = new OkHttpClient();

        Request request = new Request.Builder()
                .url(url)
                .build();

        client.newCall(request).enqueue(new Callback() {
            @Override
            public void onFailure(Call call, IOException e) {
                call.cancel();
            }

            @Override
            public void onResponse(Call call, Response response) throws IOException {

                final String myResponse = response.body().string();

                MainActivity.this.runOnUiThread(new Runnable() {
                    @Override
                    public void run() {
                        txtString.setText(myResponse);
                    }
                });

            }
        });
    }

}

OkHttp Query Parameters Example

HttpUrl.Builder urlBuilder = HttpUrl.parse("https://httpbin.org/get).newBuilder();
urlBuilder.addQueryParameter("website", "www.journaldev.com");
urlBuilder.addQueryParameter("tutorials", "android");
String url = urlBuilder.build().toString();

Request request = new Request.Builder()
                     .url(url)
                     .build();

OkHttp Android Headers Example

Request request = new Request.Builder()
    .header("Authorization", "replace this text with your token")
    .url("your api url")
    .build();

Processing the JSON Response

client.newCall(request).enqueue(new Callback() {
            @Override
            public void onFailure(Call call, IOException e) {
                call.cancel();
            }

            @Override
            public void onResponse(Call call, Response response) throws IOException {

                final String myResponse = response.body().string();

                MainActivity.this.runOnUiThread(new Runnable() {
                    @Override
                    public void run() {
                        try {

                            JSONObject json = new JSONObject(myResponse);
                            txtString.setText(json.getJSONObject("data").getString("first_name")+ " "+json.getJSONObject("data").getString("last_name"));
                        } catch (JSONException e) {
                            e.printStackTrace();
                        }
                    }
                });

            }
        });

OkHttp Android POST Example

public class MainActivity extends AppCompatActivity {

    public String postUrl= "https://reqres.in/api/users/";
    public String postBody="{\n" +
            "    \"name\": \"morpheus\",\n" +
            "    \"job\": \"leader\"\n" +
            "}";

    public static final MediaType JSON = MediaType.parse("application/json; charset=utf-8");

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        try {
            postRequest(postUrl,postBody);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    void postRequest(String postUrl,String postBody) throws IOException {

        OkHttpClient client = new OkHttpClient();

        RequestBody body = RequestBody.create(JSON, postBody);

        Request request = new Request.Builder()
                .url(postUrl)
                .post(body)
                .build();

        client.newCall(request).enqueue(new Callback() {
            @Override
            public void onFailure(Call call, IOException e) {
                call.cancel();
            }

            @Override
            public void onResponse(Call call, Response response) throws IOException {
                Log.d("TAG",response.body().string());
            }
        });
    }
}