Android Client-Server Using Sockets – Client Implementation

by guru · Published November 1, 2016 · Updated July 6, 2021

In this Android Client-Server Using Sockets post we will be focusing on client side implementation. We have covered Server side implementation in our previous post “Android Client-Server Using Sockets – Server Implementation”

Implementation Details

In this tutorial we will be using java Sockets to achieve our server-client communication. In client user will fill IP and port details in EditText and then it will press connect. Server will replay to the query. For implementation of Client we will be extending AsyncTask . Socket is created using IP and port detail and replay from server is decoded.

Note : This tutorial is based on Eclipse 4.3, Java 1.6 and Android 4.4.2.

Client Implementation

Implementing Client.java

This class contain all the implementation of client. This class is created by extending AsyncTask so that multitasking will be easy. We create a socket using IP and port detail which was provided by the user. Next getInputStream() is called on created socket to get InputStream so as to read data from this socket. Connection is blocked untill no data is read. This all must be done in try catch block so that exceptions must be handled.

package com.androidsrc.client;
 
import android.os.AsyncTask;
import android.widget.TextView;
 
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.Socket;
import java.net.UnknownHostException;
 
public class Client extends AsyncTask<Void, Void, Void> {
 
    String dstAddress;
    int dstPort;
    String response = "";
    TextView textResponse;
 
    Client(String addr, int port, TextView textResponse) {
        dstAddress = addr;
        dstPort = port;
        this.textResponse = textResponse;
    }
 
    @Override
    protected Void doInBackground(Void... arg0) {
 
        Socket socket = null;
 
        try {
            socket = new Socket(dstAddress, dstPort);
 
            ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream(
                    1024);
            byte[] buffer = new byte[1024];
 
            int bytesRead;
            InputStream inputStream = socket.getInputStream();
 
			/*
             * notice: inputStream.read() will block if no data return
			 */
            while ((bytesRead = inputStream.read(buffer)) != -1) {
                byteArrayOutputStream.write(buffer, 0, bytesRead);
                response += byteArrayOutputStream.toString("UTF-8");
            }
 
        } catch (UnknownHostException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
            response = "UnknownHostException: " + e.toString();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
            response = "IOException: " + e.toString();
        } finally {
            if (socket != null) {
                try {
                    socket.close();
                } catch (IOException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }
            }
        }
        return response;
    }
 
    @Override
    protected void onPostExecute(Void result) {
        textResponse.setText(response);
        super.onPostExecute(result);
    }
 
}

package com.androidsrc.client;

import android.os.AsyncTask;

import android.widget.TextView;

import java.io.ByteArrayOutputStream;

import java.io.IOException;

import java.io.InputStream;

import java.net.Socket;

import java.net.UnknownHostException;

public class Client extends AsyncTask<Void, Void, Void> {

String dstAddress;

int dstPort;

String response = "";

TextView textResponse;

Client(String addr, int port, TextView textResponse) {

dstAddress = addr;

dstPort = port;

this.textResponse = textResponse;

}

@Override

protected Void doInBackground(Void... arg0) {

Socket socket = null;

try {

socket = new Socket(dstAddress, dstPort);

ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream(

1024);

byte[] buffer = new byte[1024];

int bytesRead;

InputStream inputStream = socket.getInputStream();

* notice: inputStream.read() will block if no data return

while ((bytesRead = inputStream.read(buffer)) != -1) {

byteArrayOutputStream.write(buffer, 0, bytesRead);

response += byteArrayOutputStream.toString("UTF-8");

}

} catch (UnknownHostException e) {

// TODO Auto-generated catch block

e.printStackTrace();

response = "UnknownHostException: " + e.toString();

} catch (IOException e) {

// TODO Auto-generated catch block

e.printStackTrace();

response = "IOException: " + e.toString();

} finally {

if (socket != null) {

try {

socket.close();

} catch (IOException e) {

// TODO Auto-generated catch block

e.printStackTrace();

}

return response;

}

@Override

protected void onPostExecute(Void result) {

textResponse.setText(response);

super.onPostExecute(result);

}

Implementation of MainActivity.java class

The usage of client class is very simple. Just create a object of Client class and pass IP and port of server and response TextView. Here is what MainActivity.java looks like.

package com.androidsrc.client;
 
import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
 
public class MainActivity extends Activity {
 
    TextView response;
    EditText editTextAddress, editTextPort;
    Button buttonConnect, buttonClear;
 
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
 
        editTextAddress = (EditText) findViewById(R.id.addressEditText);
        editTextPort = (EditText) findViewById(R.id.portEditText);
        buttonConnect = (Button) findViewById(R.id.connectButton);
        buttonClear = (Button) findViewById(R.id.clearButton);
        response = (TextView) findViewById(R.id.responseTextView);
 
        buttonConnect.setOnClickListener(new OnClickListener() {
 
            @Override
            public void onClick(View arg0) {
                Client myClient = new Client(editTextAddress.getText()
                        .toString(), Integer.parseInt(editTextPort
                        .getText().toString()), response);
                myClient.execute();
            }
        });
 
        buttonClear.setOnClickListener(new OnClickListener() {
 
            @Override
            public void onClick(View v) {
                response.setText("");
            }
        });
    }
}

package com.androidsrc.client;

import android.app.Activity;

import android.os.Bundle;

import android.view.View;

import android.view.View.OnClickListener;

import android.widget.Button;

import android.widget.EditText;

import android.widget.TextView;

public class MainActivity extends Activity {

TextView response;

EditText editTextAddress, editTextPort;

Button buttonConnect, buttonClear;

@Override

protected void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.activity_main);

editTextAddress = (EditText) findViewById(R.id.addressEditText);

editTextPort = (EditText) findViewById(R.id.portEditText);

buttonConnect = (Button) findViewById(R.id.connectButton);

buttonClear = (Button) findViewById(R.id.clearButton);

response = (TextView) findViewById(R.id.responseTextView);

buttonConnect.setOnClickListener(new OnClickListener() {

@Override

public void onClick(View arg0) {

Client myClient = new Client(editTextAddress.getText()

.toString(), Integer.parseInt(editTextPort

.getText().toString()), response);

myClient.execute();

}

});

buttonClear.setOnClickListener(new OnClickListener() {

@Override

public void onClick(View v) {

response.setText("");

}

});

}

Other supporting components

Implementation of activity_main.xml file.

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >
 
    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center_horizontal"
        android:layout_marginTop="20dp"
        android:layout_marginBottom="20dp"
        android:autoLink="web"
        android:text="http://androidSRC.net/"
        android:textStyle="bold" />
 
    <EditText
        android:id="@+id/addressEditText"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="Server ip address" />
 
    <EditText
        android:id="@+id/portEditText"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="Server port number" />
 
    <Button
        android:id="@+id/connectButton"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="20dp"
        android:text="Connect..." />
 
    <Button
        android:id="@+id/clearButton"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Clear" />
 
    <TextView
        android:id="@+id/responseTextView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" />
 
</LinearLayout>

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"

xmlns:tools="http://schemas.android.com/tools"

android:layout_width="match_parent"

android:layout_height="match_parent"

android:orientation="vertical" >

<TextView

android:layout_width="wrap_content"

android:layout_height="wrap_content"

android:layout_gravity="center_horizontal"

android:layout_marginTop="20dp"

android:layout_marginBottom="20dp"

android:autoLink="web"

android:text="http://androidSRC.net/"

android:textStyle="bold" />

<EditText

android:id="@+id/addressEditText"

android:layout_width="match_parent"

android:layout_height="wrap_content"

android:hint="Server ip address" />

<EditText

android:id="@+id/portEditText"

android:layout_width="match_parent"

android:layout_height="wrap_content"

android:hint="Server port number" />

<Button

android:id="@+id/connectButton"

android:layout_width="match_parent"

android:layout_height="wrap_content"

android:layout_marginTop="20dp"

android:text="Connect..." />

<Button

android:id="@+id/clearButton"

android:layout_width="match_parent"

android:layout_height="wrap_content"

android:text="Clear" />

<TextView

android:id="@+id/responseTextView"

android:layout_width="wrap_content"

android:layout_height="wrap_content" />

</LinearLayout>

AndroidManifest.xml

We will need permission INTERNET to create Sockets. Don’t forget to include that permission in your manifest.

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.androidsrc.client"
    android:versionCode="1"
    android:versionName="1.0" >
 
    <uses-sdk
        android:minSdkVersion="19"
        android:targetSdkVersion="19" />
    <uses-permission android:name="android.permission.INTERNET"/>
 
    <application
        android:allowBackup="true"
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/AppTheme" >
        <activity
            android:name=".MainActivity"
            android:label="@string/app_name" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
 
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>
 
</manifest>

<?xml version="1.0" encoding="utf-8"?>

<manifest xmlns:android="http://schemas.android.com/apk/res/android"

package="com.androidsrc.client"

android:versionCode="1"

android:versionName="1.0" >

<uses-sdk

android:minSdkVersion="19"

android:targetSdkVersion="19" />

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

<application

android:allowBackup="true"

android:icon="@drawable/ic_launcher"

android:label="@string/app_name"

android:theme="@style/AppTheme" >

<activity

android:name=".MainActivity"

android:label="@string/app_name" >

<intent-filter>

</intent-filter>

</activity>

</application>

</manifest>

Testing the application

To test this application install it on android device and install client on other device. Both device should be connected to same wifi network. Now just add IP address and port to client and click connect. Server will replay with a message to client. Thanks

Any further queries or custom tutorial please comment or mail us at androidsrcdotnet@gmail.com

Android Client-Server Using Sockets – Client Implementation

Implementation Details

Client Implementation

Implementing Client.java

Implementation of MainActivity.java class

Other supporting components

Implementation of activity_main.xml file.

AndroidManifest.xml

Testing the application

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Android Client-Server Using Sockets – Client Implementation

Implementation Details

Client Implementation

Implementing Client.java

Implementation of MainActivity.java class

Other supporting components

Implementation of activity_main.xml file.

AndroidManifest.xml

Testing the application

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