WIFI to WIFI Connectivity using Android

Question

I want to transfer messages from the android device to desktop application. My question is that can i connect the android WiFi device with the desktop WiFi device without any use of internet connection. I want to use it just like the Bluetooth. is this possible or not? if it is possible then how can i implement it?

Thanks and Regards Amit Thaper

Answer 1

Here is an implementation of mreichelt's suggestion. i looked this up when i had the same problem and figured i'd just post my implementation of the solution. it's really simple. i also built a java server that listens for incoming requests from the android device (for debugging purposes mostly). here's the code to send stuff over the wireless:

import java.net.*;
import java.io.*;
import java.util.*;

import android.app.Activity;
import android.content.Context;
import android.content.ContentValues;
import android.content.SharedPreferences;
import android.content.SharedPreferences.Editor;
import android.os.Bundle;
import android.util.Log;


public class SMSConnection {
        /* The socket to the server */
    private Socket connection;

    /* Streams for reading and writing the socket */
    private BufferedReader fromServer;
    private DataOutputStream toServer;

    /* application context */
    Context mCtx;

    private static final String CRLF = "\r\n";

    /* Create an SMSConnection object. Create the socket and the 
       associated streams. Initialize SMS connection. */
    public SMSConnection(Context ctx) throws IOException {
        mCtx=ctx;
        this.open();
        /* may anticipate problems with readers being initialized before connection is opened? */
        fromServer = new BufferedReader(new InputStreamReader(connection.getInputStream()));
        toServer = new DataOutputStream(connection.getOutputStream());
    }

    public boolean open(String host, int port) {
        try {
            connection = new Socket(host, port);
            return true;
        } catch(IOException e) {
            Log.v("smswifi", "cannot open connection: " + e.toString());
        }
        return false;
    }

    /* Close the connection. */
    public void close() {
        try {
            connection.close();
        } catch (IOException e) {
            Log.v("smswifi","Unable to close connection: " + e.toString());
        }
    }

    /* Send an SMS command to the server. Check that the reply code
       is what is is supposed to be according to RFC 821. */
    public void sendCommand(String command) throws IOException {

        /* Write command to server. */
        this.toServer.writeBytes(command+this.CRLF);

        /* read reply */
        String reply = this.fromServer.readLine();
    }
}

that's a basic skeleton for a connection class. you simply instantiate the class, and call open on the instance you create with the host and port (don't forget to close the connection when you're done) and you can change the body of sendCommand to your liking. i've included a read/write operation in the function body as an example.

here is the code to run a server on a remote machine that listens for connections and spawns a thread to handle each request. it can easily interact with the above code for debugging (or any use).

import java.io.*;
import java.net.*;
import java.util.*;

public final class smsd {
    ///////MEMBER VARIABLES
    ServerSocket server=null;
    Socket client=null;

    ///////MEMBER FUNCTIONS
    public boolean createSocket(int port) {
        try{
            server = new ServerSocket(port);
            } catch (IOException e) {
            System.out.println("Could not listen on port "+port);
            System.exit(-1);
        }
        return true;
    }

    public boolean listenSocket(){
        try{
            client = server.accept();
        } catch (IOException e) {
            System.out.println("Accept failed: ");
            System.exit(-1);
        }
        return true;
    }

    public static void main(String argv[]) throws Exception {
        //
        smsd mySock=new smsd();

        //establish the listen socket
        mySock.createSocket(3005);
        while(true) {
            if(mySock.listenSocket()) {
                //make new thread
                // Construct an object to process the SMS request message.
                SMSRequest request = new SMSRequest(mySock.client);

                // Create a new thread to process the request.
                Thread thread = new Thread(request);

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

        //process SMS service requests in an infinite loop

    }
///////////end class smsd/////////
}


final class SMSRequest implements Runnable {
    //
    final static String CRLF = "\r\n";
    Socket socket;

    // Constructor
    public SMSRequest(Socket socket) throws Exception 
    {
        this.socket = socket;
    }

    // Implement the run() method of the Runnable interface.
    public void run()
    {
        try {
            processRequest();
        } catch (Exception e) {
            System.out.println(e);
        }
    }

    private static void sendBytes(FileInputStream fis, OutputStream os) throws Exception
        {
           // Construct a 1K buffer to hold bytes on their way to the socket.
           byte[] buffer = new byte[1024];
           int bytes = 0;

           // Copy requested file into the socket's output stream.
           while((bytes = fis.read(buffer)) != -1 ) {
              os.write(buffer, 0, bytes);
           }
        }

    private void processRequest() throws Exception
    {
        // Get a reference to the socket's input and output streams.
        InputStream is = this.socket.getInputStream();
        DataOutputStream os = new DataOutputStream(this.socket.getOutputStream());

        // Set up input stream filters.
        InputStreamReader isr = new InputStreamReader(is);
        BufferedReader br = new BufferedReader(isr);

        // Get the request line of the SMS request message.
        String requestLine = br.readLine();

        //print message to screen
        System.out.println(requestLine);

        //send a reply
        os.writeBytes("200");

        // Close streams and socket.
        os.close();
        br.close();
        socket.close();
    }
}

nb4namingconventions.

almost forgot. you will need to set these permissions inside the tags in your AndroidManifest.xml in order to use wireless.

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