Android OkHttp3 Http Get Post Request Example

2 Comments / Android Tutorial

This example will show you how to use OkHttp3 to send get or post HTTP request to a web server and how to parse and display response text in an Android TextView.

1. OKHttp Characters.

  1. OkHttp3 is a third-party open-source library that is contributed by the square company. It has below characters.
  2. User-friendly API.
  3. Support http2, sharing the same socket for all requests from a machine.
  4. Built-in connection pool, support for connection reuse, and reduction of delay.
  5. Supports transparent gzip compression response.
  6. Avoid duplicate requests by caching.
  7. Automatically retry the host’s other IP and redirect automatically when the request fails.

2. Add OkHttp3 Library In build.gradle.

  1. Before you can use the OkHttp3 library, you need to add dependencies in the build.gradle file in android studio as below.
  2. You can get the most recent build library from https://github.com/square/okhttp.
  3. After adding the below code, you need to click the Sync Now link in the top right corner to sync the project. 
    dependencies {
    compile fileTree(include: ['*.jar'], dir: 'libs')
    androidTestCompile('com.android.support.test.espresso:espresso-core:2.2.2', {
        exclude group: 'com.android.support', module: 'support-annotations'
    })
    compile 'com.android.support:appcompat-v7:26.+'
    compile 'com.android.support.constraint:constraint-layout:1.0.2'
    compile 'com.android.support:design:26.+'
    compile 'com.android.support:percent:24.2.1'
    compile 'com.android.support:recyclerview-v7:26.+'
    compile 'com.google.android:flexbox:0.3.0'
    compile 'com.google.code.gson:gson:2.8.2'
    compile 'com.squareup.okhttp3:okhttp:3.10.0'
    testCompile 'junit:junit:4.12'
}

2. Use OkHttp3 To Create HTTP Get Request Method Call Object.

  1. The below source code snippet will use the OkHttp3 library to create an HTTP GET request. 
    // Create okhttp3 request builder.
Request.Builder builder = new Request.Builder();

// Set url.
builder = builder.url(url);

// Create request object.
Request request = builder.build();

// Create a new Call object.
Call call = okHttpClient.newCall(request);

3. Use OkHttp3 To Create HTTP Post Request Method Call Object.

  1. The below source code snippet will use the OkHttp3 library to create an HTTP POST request. 
    // Create okhttp3 form body builder.
FormBody.Builder formBodyBuilder = new FormBody.Builder();

// Add form parameters
formBodyBuilder.add("q", "trump");
formBodyBuilder.add("first", "2");

// Build form body.
FormBody formBody = formBodyBuilder.build();

// Create a http request object.
Request.Builder builder = new Request.Builder();
builder = builder.url(url);
builder = builder.post(formBody);
Request request = builder.build();

// Create a new Call object with the post method.
Call call = okHttpClient.newCall(request);

4. Send Http Request Synchronously And Asynchronously.

  1. You can send HTTP GET or POST requests with OkHttp3 synchronously or asynchronously.
  2. When you send the request synchronously, you need to run the code in a child thread because the process may take a long time. 
    // Execute the request and get the response synchronously.
Response response = call.execute();
  3. When you send the request asynchronously, the system will create a child thread and run OkHttp3 code in it automatically. 
    // Execute the request and get the response asynchronously.
call.enqueue(new Callback() {......});

5. OkHttp Get Post Request Example.

5.1 Main Activity.

  1. OkHttpActivity.java 
    package com.dev2qa.example.network;

import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.support.v7.app.AppCompatActivity;
import android.util.Log;
import android.view.View;
import android.webkit.URLUtil;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;

import com.dev2qa.example.R;

import java.io.IOException;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Set;

import okhttp3.Call;
import okhttp3.Callback;
import okhttp3.FormBody;
import okhttp3.Headers;
import okhttp3.OkHttpClient;
import okhttp3.Request;
import okhttp3.Response;

public class OkHttpActivity extends AppCompatActivity {

    private static final String TAG_OK_HTTP_ACTIVITY = "OK_HTTP_ACTIVITY";

    private EditText pageUrlEditor = null;

    private Button syncGetButton = null;

    private Button asyncGetButton = null;

    private Button syncPostButton = null;

    private Button asyncPostButton = null;

    // Display server response text.
    private TextView respTextView = null;

    private OkHttpClient okHttpClient = null;

    // Process child thread sent command to show server response text in activity main thread.
    private Handler displayRespTextHandler = null;

    private static final int COMMAND_DISPLAY_SERVER_RESPONSE = 1;

    private static final String KEY_SERVER_RESPONSE_OBJECT = "KEY_SERVER_RESPONSE_OBJECT";

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

        setTitle("dev2qa.com - Android OkHttpClient Example");

        // Init okhttp3 example controls.
        initControls();

        // Click this button to get url response synchronous.
        syncGetButton.setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View v) {

                String url = pageUrlEditor.getText().toString();
                if (!URLUtil.isHttpUrl(url) && !URLUtil.isHttpsUrl(url)) {
                    Toast.makeText(getApplicationContext(), "Please input a url start with http or https.", Toast.LENGTH_LONG).show();
                }else {

                    // For synchronous actions, it must start a child thread to process.
                    // Otherwise, the activity main thread will throw an exception.
                    Thread okHttpExecuteThread = new Thread() {
                        @Override
                        public void run() {

                            String url = pageUrlEditor.getText().toString();

                            try {

                                // Create okhttp3.Call object with the HTTP request GET method.
                                Call call = createHttpGetMethodCall(url);

                                // Execute the request and get the response synchronously.
                                Response response = call.execute();

                                // If request process success.
                                boolean respSuccess = response.isSuccessful();
                                if (respSuccess) {

                                    // Parse and get server response text data.
                                    String respData = parseResponseText(response);

                                    // Notify activity main thread to update UI display text with Handler.
                                    sendChildThreadMessageToMainThread(respData);
                                } else {
                                    sendChildThreadMessageToMainThread("Ok http get request failed.");
                                }
                            } catch (Exception ex) {
                                Log.e(TAG_OK_HTTP_ACTIVITY, ex.getMessage(), ex);
                                sendChildThreadMessageToMainThread(ex.getMessage());
                            }
                        }
                    };

                    // Start the child thread.
                    okHttpExecuteThread.start();
                }
            }
        });

        // Click this button to get url response asynchronous.
        asyncGetButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                String url = pageUrlEditor.getText().toString();
                if (!URLUtil.isHttpUrl(url) && !URLUtil.isHttpsUrl(url)) {
                    Toast.makeText(getApplicationContext(), "Please input a url start with http or https.", Toast.LENGTH_LONG).show();
                }else {

                    try {
                        // Create okhttp3.Call object with get http request method.
                        Call call = createHttpGetMethodCall(url);

                        // Execute the request and get the response asynchronously.
                        call.enqueue(new Callback() {
                            @Override
                            public void onFailure(Call call, IOException e) {
                                sendChildThreadMessageToMainThread("Asynchronous http get request failed.");
                            }

                            @Override
                            public void onResponse(Call call, Response response) throws IOException {
                                if (response.isSuccessful()) {
                                    // Parse and get server response text data.
                                    String respData = parseResponseText(response);

                                    // Notify activity main thread to update UI display text with Handler.
                                    sendChildThreadMessageToMainThread(respData);
                                }
                            }
                        });
                    }catch(Exception ex)
                    {
                        Log.e(TAG_OK_HTTP_ACTIVITY, ex.getMessage(), ex);
                        sendChildThreadMessageToMainThread(ex.getMessage());
                    }
                }
            }
        });

        // Click this button to post data to url synchronously.
        syncPostButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                String url = pageUrlEditor.getText().toString();
                if (!URLUtil.isHttpUrl(url) && !URLUtil.isHttpsUrl(url)) {
                    Toast.makeText(getApplicationContext(), "Please input a url start with http or https.", Toast.LENGTH_LONG).show();
                }else {

                    // For synchronous actions, it must start a child thread to process.
                    // Otherwise, the activity main thread will throw an exception.
                    Thread okHttpExecuteThread = new Thread() {
                        @Override
                        public void run() {

                            String url = pageUrlEditor.getText().toString();

                            try {

                                // Create okhttp3.Call object with the HTTP request POST method.
                                Call call = createHttpPostMethodCall(url);

                                // Execute the request and get the response synchronously.
                                Response response = call.execute();

                                // If request process success.
                                boolean respSuccess = response.isSuccessful();
                                if (respSuccess) {

                                    // Parse and get server response text data.
                                    String respData = parseResponseText(response);

                                    // Notify activity main thread to update UI display text with Handler.
                                    sendChildThreadMessageToMainThread(respData);
                                } else {
                                    sendChildThreadMessageToMainThread("Ok http post request failed.");
                                }
                            } catch(Exception ex)
                            {
                                Log.e(TAG_OK_HTTP_ACTIVITY, ex.getMessage(), ex);
                                sendChildThreadMessageToMainThread(ex.getMessage());
                            }
                        }
                    };

                    // Start the child thread.
                    okHttpExecuteThread.start();
                }
            }
        });

        // Click this button to send post data to url asynchronously.
        asyncPostButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                String url = pageUrlEditor.getText().toString();
                if (!URLUtil.isHttpUrl(url) && !URLUtil.isHttpsUrl(url)) {
                    Toast.makeText(getApplicationContext(), "Please input a url start with http or https.", Toast.LENGTH_LONG).show();
                }else {
                    try
                    {
                        // Create okhttp3.Call object with the http request POST method.
                        Call call = createHttpPostMethodCall(url);

                        // Execute the request and get the response asynchronously.
                        call.enqueue(new Callback() {
                            @Override
                            public void onFailure(Call call, IOException e) {
                                sendChildThreadMessageToMainThread("Asynchronous http post request failed.");
                            }

                            @Override
                            public void onResponse(Call call, Response response) throws IOException {
                                if(response.isSuccessful())
                                {
                                    // Parse and get server response text data.
                                    String respData = parseResponseText(response);

                                    // Notify activity main thread to update UI display text with Handler.
                                    sendChildThreadMessageToMainThread(respData);
                                }
                            }
                        });
                    }catch(Exception ex)
                    {
                        Log.e(TAG_OK_HTTP_ACTIVITY, ex.getMessage(), ex);
                        sendChildThreadMessageToMainThread(ex.getMessage());
                    }
                }
            }
        });
    }

    /* Initialize okhttp3 example controls */
    private void initControls()
    {
        if(pageUrlEditor == null)
        {
            pageUrlEditor = (EditText)findViewById(R.id.ok_http_url_editor);
        }

        if(syncGetButton == null)
        {
            syncGetButton = (Button)findViewById(R.id.ok_http_client_synchronous_get);
        }

        if(asyncGetButton == null)
        {
            asyncGetButton = (Button)findViewById(R.id.ok_http_client_asynchronous_get);
        }

        if(syncPostButton == null)
        {
            syncPostButton = (Button)findViewById(R.id.ok_http_client_synchronous_post);
        }

        if(asyncPostButton == null)
        {
            asyncPostButton = (Button)findViewById(R.id.ok_http_client_asynchronous_post);
        }

        if(respTextView == null)
        {
            respTextView = (TextView)findViewById(R.id.ok_http_client_resp_text_view);
        }

        if(displayRespTextHandler == null)
        {
            displayRespTextHandler = new Handler()
            {
                // When this handler receives a message from the child thread.
                @Override
                public void handleMessage(Message msg) {

                    // Check what this message want to do.
                    if(msg.what == COMMAND_DISPLAY_SERVER_RESPONSE)
                    {
                        // Get server response text.
                        Bundle bundle = msg.getData();
                        String respText = bundle.getString(KEY_SERVER_RESPONSE_OBJECT);

                        // Display server response text in text view.
                        respTextView.setText("");
                        respTextView.scrollTo(0,0);
                        respTextView.setText(respText);
                    }
                }
            };
        }

        if(okHttpClient == null)
        {
            okHttpClient = new OkHttpClient();
        }
    }

    /* Create OkHttp3 Call object use get method with url. */
    private Call createHttpGetMethodCall(String url)
    {
        // Create okhttp3 request builder.
        Request.Builder builder = new Request.Builder();

        // Set url.
        builder = builder.url(url);

        // Create request object.
        Request request = builder.build();

        // Create a new Call object.
        Call call = okHttpClient.newCall(request);

        return call;
    }

    /* Create OkHttp3 Call object use post method with url. */
    private Call createHttpPostMethodCall(String url)
    {
        // Create okhttp3 form body builder.
        FormBody.Builder formBodyBuilder = new FormBody.Builder();

        // Add form parameter
        formBodyBuilder.add("q", "trump");
        formBodyBuilder.add("first", "2");

        // Build form body.
        FormBody formBody = formBodyBuilder.build();

        // Create a http request object.
        Request.Builder builder = new Request.Builder();
        builder = builder.url(url);
        builder = builder.post(formBody);
        Request request = builder.build();

        // Create a new Call object with the post method.
        Call call = okHttpClient.newCall(request);

        return call;
    }

    /* Parse response code, message, headers and body string from server response object. */
    private String parseResponseText(Response response)
    {
        // Get response code.
        int respCode = response.code();

        // Get message
        String respMsg = response.message();

        // Get headers.
        List<String> headerStringList = new ArrayList<String>();

        Headers headers = response.headers();
        Map<String, List<String>> headerMap = headers.toMultimap();
        Set<String> keySet = headerMap.keySet();
        Iterator<String> it = keySet.iterator();
        while(it.hasNext())
        {
            String headerKey = it.next();
            List<String> headerValueList = headerMap.get(headerKey);

            StringBuffer headerBuf = new StringBuffer();
            headerBuf.append(headerKey);
            headerBuf.append(" = ");

            for(String headerValue : headerValueList)
            {
                headerBuf.append(headerValue);
                headerBuf.append(" , ");
            }

            headerStringList.add(headerBuf.toString());
        }


        // Get body text.
        String respBody = "";
        try {
            respBody = response.body().string();
        }catch(IOException ex)
        {
            Log.e(TAG_OK_HTTP_ACTIVITY, ex.getMessage(), ex);
        }

        // Create a server response dto.
        ServerResponseDTO respDto = new ServerResponseDTO();
        respDto.setRespCode(respCode);
        respDto.setRespMessage(respMsg);
        respDto.setHeaderStringList(headerStringList);
        respDto.setRespBody(respBody);

        return respDto.toString();
    }

    // Send message from child thread to activity main thread.
    // Because can not modify UI controls in child thread directly.
    private void sendChildThreadMessageToMainThread(String respData)
    {
        // Create a Message object.
        Message message = new Message();

        // Set message type.
        message.what = COMMAND_DISPLAY_SERVER_RESPONSE;

        // Set server response text data.
        Bundle bundle = new Bundle();
        bundle.putString(KEY_SERVER_RESPONSE_OBJECT, respData);
        message.setData(bundle);

        // Send message to activity Handler.
        displayRespTextHandler.sendMessage(message);
    }
}

5.2 Layout XML File.

  1. activity_ok_http.xml 
    <LinearLayout
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:orientation="vertical">

    <EditText
        android:id="@+id/ok_http_url_editor"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="Input web page url start with http or https."/>

    <Button
        android:id="@+id/ok_http_client_synchronous_get"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Synchronous Get"/>

    <Button
        android:id="@+id/ok_http_client_asynchronous_get"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Asynchronous Get"/>

    <Button
        android:id="@+id/ok_http_client_synchronous_post"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Synchronous Post"/>

    <Button
        android:id="@+id/ok_http_client_asynchronous_post"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Asynchronous Post"/>

    <ScrollView
        android:layout_width="match_parent"
        android:layout_height="wrap_content">

        <TextView
            android:id="@+id/ok_http_client_resp_text_view"
            android:layout_width="match_parent"
            android:layout_height="wrap_content" />

    </ScrollView>
</LinearLayout>

5.3 Android Manifest Xml File.

  1. AndroidManifest.xml 
    <?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.dev2qa.example">

    <!-- Example required permission. -->
<uses-permission android:name="android.permission.INTERNET" />   
    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">
        
        <activity android:name=".network.OkHttpActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>
  2. Please Note: Do not show Toast message in a child thread, otherwise it will through the below error. 
    java.lang.RuntimeException: Can't create handler inside thread that has not called Looper.prepare()

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