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Android:Example:SocketServer

lastmod 2018-08-17created 2016-12-122 edits

A sample example that creates a Server Socket and a Client Socket on Android (Android to Android), and has the server echo (ECHO) the string sent by the client.

Manifest

On both the server and client side, add the permissions to AndroidManifest.xml as shown below. 

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

Server

Add one TextView with the ID text2 to Layout.xml. 

package com.blackhole.jupiter;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.ServerSocket;
import java.net.Socket;

import android.app.Activity;
import android.os.Bundle;
import android.os.Handler;
import android.view.Menu;
import android.widget.TextView;

public class FirstActivity extends Activity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_first);
        text = (TextView) findViewById(R.id.text2);
        updateConversationHandler = new Handler();
        this.serverThread = new Thread(new ServerThread());
        this.serverThread.start();
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.first, menu);
        return true;
    }

    private ServerSocket serverSocket;
    Handler updateConversationHandler;
    Thread serverThread = null;
    private TextView text;

    public static final int SERVERPORT = 6000;

    @Override
    protected void onStop() {
        super.onStop();
        try {
            serverSocket.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    class ServerThread implements Runnable {
        public void run() {
            Socket socket = null;
            try {
                serverSocket = new ServerSocket(SERVERPORT);
            } catch (IOException e) {
                e.printStackTrace();
            }
            while (!Thread.currentThread().isInterrupted()) {
                try {
                    socket = serverSocket.accept();
                    CommunicationThread commThread = new CommunicationThread(socket);
                    new Thread(commThread).start();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    }

    class CommunicationThread implements Runnable {
        private Socket clientSocket;
        private BufferedReader input;

        public CommunicationThread(Socket clientSocket) {
            this.clientSocket = clientSocket;
            try {
                this.input = new BufferedReader(new InputStreamReader(this.clientSocket.getInputStream()));
            } catch (IOException e) {
                e.printStackTrace();
            }
        }

        public void run() {
            while (!Thread.currentThread().isInterrupted()) {
                try {
                    String read = input.readLine();
                    updateConversationHandler.post(new updateUIThread(read));
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    }

    class updateUIThread implements Runnable {
        private String msg;

        public updateUIThread(String str) {
            this.msg = str;
        }

        @Override
        public void run() {
            text.setText(text.getText().toString() + "Client Says: " + msg + "\n");
        }
    }
}

Client

Add one EditText with the ID EditText01 and one Button whose click event is bound to the onClick() method to Layout.xml. 

package com.blackhole.worldit;

import java.io.BufferedWriter;
import java.io.IOException;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.net.InetAddress;
import java.net.Socket;
import java.net.UnknownHostException;

import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.widget.EditText;

public class FirstActivity extends Activity {

    private Socket socket;

    private static final int SERVERPORT = 6000;
    private static final String SERVER_IP = "192.168.0.43";

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_first);
        new Thread(new ClientThread()).start();
    }

    public void onClick(View view) {
        try {
            EditText et = (EditText) findViewById(R.id.EditText01);
            String str = et.getText().toString();
            PrintWriter out = new PrintWriter(new BufferedWriter(new OutputStreamWriter(socket.getOutputStream())), true);
            out.println(str);
        } catch (UnknownHostException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    class ClientThread implements Runnable {
        @Override
        public void run() {
            try {
                InetAddress serverAddr = InetAddress.getByName(SERVER_IP);
                socket = new Socket(serverAddr, SERVERPORT);
            } catch (UnknownHostException e1) {
                e1.printStackTrace();
            } catch (IOException e1) {
                e1.printStackTrace();
            }
        }
    }
}

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