Android Server/Client example - server side using ServerSocket

It's the server side implementation of our Server/Client example, the client side is listed in next post "client side using Socket".

Android Server using ServerSocket

In this server side implementation, it will list its own IP address when program start. And run in background thread, start a ServerSocket and wait at serverSocket.accept(). Once any request received, it return a message to client side.

package com.example.androidserversocket;

import java.io.IOException;
import java.io.OutputStream;
import java.io.PrintStream;
import java.net.InetAddress;
import java.net.NetworkInterface;
import java.net.ServerSocket;
import java.net.Socket;
import java.net.SocketException;
import java.util.Enumeration;

import android.os.Bundle;
import android.app.Activity;
import android.widget.TextView;

public class MainActivity extends Activity {

 TextView info, infoip, msg;
 String message = "";
 ServerSocket serverSocket;

 @Override
 protected void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.activity_main);
  info = (TextView) findViewById(R.id.info);
  infoip = (TextView) findViewById(R.id.infoip);
  msg = (TextView) findViewById(R.id.msg);
  
  infoip.setText(getIpAddress());

  Thread socketServerThread = new Thread(new SocketServerThread());
  socketServerThread.start();
 }

 @Override
 protected void onDestroy() {
  super.onDestroy();

  if (serverSocket != null) {
   try {
    serverSocket.close();
   } catch (IOException e) {
    // TODO Auto-generated catch block
    e.printStackTrace();
   }
  }
 }

 private class SocketServerThread extends Thread {

  static final int SocketServerPORT = 8080;
  int count = 0;

  @Override
  public void run() {
   try {
    serverSocket = new ServerSocket(SocketServerPORT);
    MainActivity.this.runOnUiThread(new Runnable() {

     @Override
     public void run() {
      info.setText("I'm waiting here: "
        + serverSocket.getLocalPort());
     }
    });

    while (true) {
     Socket socket = serverSocket.accept();
     count++;
     message += "#" + count + " from " + socket.getInetAddress()
       + ":" + socket.getPort() + "\n";

     MainActivity.this.runOnUiThread(new Runnable() {

      @Override
      public void run() {
       msg.setText(message);
      }
     });

     SocketServerReplyThread socketServerReplyThread = new SocketServerReplyThread(
       socket, count);
     socketServerReplyThread.run();

    }
   } catch (IOException e) {
    // TODO Auto-generated catch block
    e.printStackTrace();
   }
  }

 }

 private class SocketServerReplyThread extends Thread {

  private Socket hostThreadSocket;
  int cnt;

  SocketServerReplyThread(Socket socket, int c) {
   hostThreadSocket = socket;
   cnt = c;
  }

  @Override
  public void run() {
   OutputStream outputStream;
   String msgReply = "Hello from Android, you are #" + cnt;

   try {
    outputStream = hostThreadSocket.getOutputStream();
             PrintStream printStream = new PrintStream(outputStream);
             printStream.print(msgReply);
             printStream.close();

    message += "replayed: " + msgReply + "\n";

    MainActivity.this.runOnUiThread(new Runnable() {

     @Override
     public void run() {
      msg.setText(message);
     }
    });

   } catch (IOException e) {
    // TODO Auto-generated catch block
    e.printStackTrace();
    message += "Something wrong! " + e.toString() + "\n";
   }

   MainActivity.this.runOnUiThread(new Runnable() {

    @Override
    public void run() {
     msg.setText(message);
    }
   });
  }

 }

 private String getIpAddress() {
  String ip = "";
  try {
   Enumeration<NetworkInterface> enumNetworkInterfaces = NetworkInterface
     .getNetworkInterfaces();
   while (enumNetworkInterfaces.hasMoreElements()) {
    NetworkInterface networkInterface = enumNetworkInterfaces
      .nextElement();
    Enumeration<InetAddress> enumInetAddress = networkInterface
      .getInetAddresses();
    while (enumInetAddress.hasMoreElements()) {
     InetAddress inetAddress = enumInetAddress.nextElement();

     if (inetAddress.isSiteLocalAddress()) {
      ip += "SiteLocalAddress: " 
        + inetAddress.getHostAddress() + "\n";
     }
     
    }

   }

  } catch (SocketException e) {
   // TODO Auto-generated catch block
   e.printStackTrace();
   ip += "Something Wrong! " + e.toString() + "\n";
  }

  return ip;
 }
}

<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"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context=".MainActivity" >

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center_horizontal"
        android:autoLink="web"
        android:text="http://android-er.blogspot.com/"
        android:textStyle="bold" />

    <TextView
        android:id="@+id/info"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" />
    <TextView
        android:id="@+id/infoip"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" />

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

        <TextView
            android:id="@+id/msg"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content" />
    </ScrollView>

</LinearLayout>

Remark: uses-permission of "android.permission.INTERNET" is needed.

Download the files.



*** Updated example: Bi-directional communication between Client and Server, using ServerSocket, Socket, DataInputStream and DataOutputStream.