Bluetooth in J2ME :- Simple chat application pot

Bluetooth in J2ME :- Simple chat application Posted by vaibhav In previous tutorial , we learned about Bluetooth Device Discovery.. Here is the code for the Bluetooth Chat:-2 .java files

Bluetooth in J2ME :- Simple chat application

Posted by vaibhav

In previous tutorial , we learned about Bluetooth Device Discovery.

In this tutorial we will learn ,how to make simple bluetooth connection In this we will implement the code in which approval for connection is not required by the sender Reciever automatically recieves the sent text

Here is the code for the Bluetooth Chat:-(2 java files )

Client.java:-import java.io.*;

import javax.bluetooth.*;

import javax.microedition.io.Connector;

import javax.microedition.io.StreamConnection;

import javax.microedition.lcdui.*;

import javax.microedition.midlet.*;

/*

* @author Vaibhav

*/

public class Client extends MIDlet implements CommandListener,DiscoveryListener,Runnable {

private Display display;

public List devicelist;

private final List deviceList;

public DiscoveryAgent agent;

public String deviceName,address;

private Command Refresh,connect,end,Exit;

private String s,url;

private Alert dialog1;

private StreamConnection conn;

private Server b;

private DataOutputStream dos;

private String[][] array[][] ;

Thread t;

public Form ChatForm = new Form("chat window");

private Command send,exit;

private TextField textfield;

private String sendmsg;

public Client()

{

deviceList = new List("List of Devices",List.IMPLICIT);

Exit= new Command("Exit",Command.EXIT, 0);

connect = new Command("connect",Command.SCREEN, 1);

Refresh = new Command("Refresh",Command.SCREEN, 1);

end = new Command("End",Command.EXIT, 1);

deviceList.addCommand(Exit);

deviceList.addCommand(connect);

deviceList.addCommand(Refresh);

deviceList.setCommandListener(this);

Display.getDisplay(this).setCurrent(deviceList);

t = new Thread(this);

}

public void startApp() throws MIDletStateChangeException {

try {

b=new Server(this);

getChatForm();

deviceList.deleteAll();

LocalDevice local = LocalDevice.getLocalDevice();

address = local.getBluetoothAddress();

agent = local.getDiscoveryAgent();

} catch (BluetoothStateException ex) {

throw new MIDletStateChangeException("Unable to retrieve local Bluetooth device."); }

}

public void pauseApp() {

}

public void clear() throws IOException

{

b.destroy();

}

public void destroyApp(boolean unconditional) throws MIDletStateChangeException{

notifyDestroyed();

}

public void commandAction(Command c, Displayable d) {

if(c==Exit)

{

try {

dos.writeUTF("eof");

} catch (IOException ex) {

ex.printStackTrace();

}

notifyDestroyed();

}

if(c==Refresh){

try {

try {

agent.startInquiry(DiscoveryAgent.GIAC, this);

dialog1 = new Alert("Searching","Please Wait ,Searching devices",null,AlertType.INFO); dialog1.setTimeout(1000);

Display.getDisplay(this).setCurrent(dialog1);

} catch (BluetoothStateException e) {

throw new MIDletStateChangeException("Unable to start the inquiry");

}

} catch (MIDletStateChangeException ex) {

ex.printStackTrace();

}

}

if(c==connect){

Display.getDisplay(this).setCurrent(ChatForm);

s= deviceList.getString(deviceList.getSelectedIndex());

url = "btspp://"+ s + ":" + "1" ;

System.out.println(url);

t.start();

}

if(c==send){

sendmsg = textfield.getString() ;

textfield.setString("");

this.ChatForm.append("\n"+"ME: "+sendmsg);

try {

dos.writeUTF(address+sendmsg);

} catch (IOException ex) {

ex.printStackTrace();

}

}

}

public void deviceDiscovered(RemoteDevice btDevice, DeviceClass cod) {

try {

String deviceaddress = btDevice.getBluetoothAddress();

String address = btDevice.getFriendlyName(true);

deviceList.insert(0, deviceaddress , null);

} catch (IOException ex) {

ex.printStackTrace();

}

}

public void servicesDiscovered(int transID, ServiceRecord[] servRecord) {

}

public void serviceSearchCompleted(int transID, int respCode) {

}

public void inquiryCompleted(int discType) {

Alert dialog = null;

if (discType != DiscoveryListener.INQUIRY_COMPLETED) {

dialog = new Alert("Bluetooth Error","The inquiry failed to complete normally",null, AlertType.ERROR); }

else {

dialog = new Alert("Inquiry Completed","The inquiry completed normally", null,AlertType.INFO); }

dialog.setTimeout(500);

Display.getDisplay(this).setCurrent(dialog);

}

public void run() {

try {

conn = (StreamConnection) Connector.open(url);

dos = conn.openDataOutputStream();

} catch (Exception ex) {

System.out.println("here");

ex.printStackTrace();

}

}

public void setText(String s)

{

this.ChatForm.append("\n"+"Friend: "+s);

}

public void getChatForm()

{

textfield = new TextField("type text ","",50,TextField.ANY);

exit = new Command ("Exit", Command.EXIT,1);

send = new Command ("send",Command.OK,1);

ChatForm.append(textfield);

ChatForm.append(" -");

ChatForm.addCommand(exit);

ChatForm.addCommand(send);

ChatForm.setCommandListener(this);

}

void setUp(String url1)

{

try{

url = "btspp://"+ url1 + ":" + "1" ;

t.start();

}catch(Exception e){

e.printStackTrace();

}

}

}

-

Server.java:-import java.io.*;

import javax.bluetooth.*;

import javax.microedition.io.*;

import javax.microedition.lcdui.Display;

/**

* @author Vaibhav

*/

public class Server implements Runnable {

public DataInputStream dis;

private StreamConnection con;

public boolean listening = false;

private Client Client;

StreamConnectionNotifier notifier = null ;

String msg,msg1,msg2;

int count;

public Server(Client Client)

{

this.Client = Client;

count=0;

try{

Thread t = new Thread(this);

t.start();

}

catch(Exception e)

{}

}

public void run() {

try {

// retrieve the local Bluetooth device object

LocalDevice localDevice = LocalDevice.getLocalDevice();

// retrieve the Bluetooth address of the local device

String address = localDevice.getBluetoothAddress();

// retrieve the name of the local Bluetooth device

String deviceName = localDevice.getFriendlyName();

System.out.println(address+" "+deviceName);

DiscoveryAgent agent =localDevice.getDiscoveryAgent();

localDevice.setDiscoverable(DiscoveryAgent.GIAC);

UUID uuid = new UUID(0x0009);

String url = "btspp://localhost:" + uuid + ";name=" + deviceName + ";" + "authenticate=true" ;

notifier = (StreamConnectionNotifier) Connector.open(url);

con =notifier.acceptAndOpen();

dis =con.openDataInputStream();

listening = true;

setChat();

}

catch (Exception ex) {

ex.printStackTrace();

}

}

public void destroy() throws IOException

{

notifier.close();

listening = false;

}

public void setChat()

{

try{

while(listening)

{

msg = dis.readUTF();

msg1=msg.substring(0,12);

msg2=msg.substring(12);

if(count==0)

{

Client.setUp(msg1);

}

count=1;

try{

if(!msg2.equals("eof")){

Display.getDisplay(Client).setCurrent(Client.ChatForm); System.out.println(msg2);

Client.setText(msg2);

}

else

listening=false;

}

catch(Exception e)

{

e.printStackTrace();

}

}

}

catch(Exception ex)

{

ex.printStackTrace();

}

}

}

-Now first we will go through the Midlet Client.java

As you can see ,it is almost similar to the previous tutorial code ,device discovery

When constructor client runs ,it initialises the Displayable item

StartApp() meanwhile creates the instance of Server class and calls its constructor

It also calls getChatForm() which defined the display of chatform as you can see in the getChatForm function code

Rest of the command is same as it was in device discovery

Now when refresh button is pressed, then the mobile searches for bletooth device through startInquiry(0 as explained in previous tutorial

After we have got a list of devices and then we press connect on selected address then the commandaction of connect comes into play

It checks for the selected device , gets its address and creates a URL as visible in following statements s= deviceList.getString(deviceList.getSelectedIndex());

url = "btspp://"+ s + ":" + "1" ;

Then the Thread is started

The run function is excecuted , in which

conn = (StreamConnection) Connector.open(url);

dos = conn.openDataOutputStream();

commands creates a stream connection to the url created in connect command

Then a dataoutput stream is opened to send data

Now when send command is given ,

sendmsg = textfield.getString() ; gets the string entered

This append the sent message to sender's screen

this.ChatForm.append("\n"+"ME: "+sendmsg);

Then this command sends the data and address of the sending mobile through outputstreamconnection

This concludes client side coding

Now in server class,as soon as its instance is created by client ,its constructor runs

this.Client = Client;

Above command hepls the class to locate its parent class

Then it starts the thread

The run function on server is executed

This statement retrieves the local Bluetooth device object

LocalDevice localDevice = LocalDevice.getLocalDevice()

;

Then it retrieve the Bluetooth address of the local device

String address = localDevice.getBluetoothAddress();

This retrieve the name of the local Bluetooth device

String deviceName = localDevice.getFriendlyName();

This creates a discoveryagent

DiscoveryAgent agent =localDevice.getDiscoveryAgent();

This sets the device as discoverable.Check for other options available for hiding the device

localDevice.setDiscoverable(DiscoveryAgent.GIAC);

UUID uuid = new UUID(0x0009);

String url = "btspp://localhost:" + uuid + ";name=" + deviceName + ";" +

"authenticate=true" ;

above 2 statements prepares the Connection URL

This statement creates the connection notifier

notifier = (StreamConnectionNotifier) Connector.open(url);

Now the essence of our coding was that it didn't required approval here is the piece of code which decides it con =notifier.acceptAndOpen();

It automatically accepts incoming connection and opens stream

dis =con.openDataInputStream();

Then setchat function is executed

msg = dis.readUTF();

msg1=msg.substring(0,12);

msg2=msg.substring(12);

Above coding is done to seperate address and the text so that address can be used to connect back to the sender and data is displayed on chatform (however setText function of client is used for this purpose.)

However when count is 0 ,it calls setUp function This is done when the reciever recieves data for the first time This is done so that it can connect back to the sender to reply However when reciever sends back 2nd time ,the count increses to more than 0 and it skips this part

Finally setUp function of client just prepares the connection URL for server to connect back

This concludes our tutorial

In next tutorial we'll learn request/response connection in which reciever can accept /reject the connection

http://delhidaredevilzgalary.blogspot.com/2011/07/bluetooth-in-j2me-bluetooth-device.html

Bluetooth in J2ME : Bluetooth Device Discovery

Posted by vaibhav

In this tutorial we will learn about Mobile Bluetooth and its application using J2ME

First of all , for all those who give more importance to underlying protocols , i found a beautiful explaination on this

site:-http://developers.sun.com/mobility/midp/articles/bluetooth1

Now after you know basic protocol structure (However its not mandatory to create application) , we can start with the modules we have to follow

In Bluetooth programming wehave following jobs in our

• Request/Response for Connection

In this particular tutorial we'll be limiting ourselves to device discovery only

Rest we'll cover in subsequent posts

First of all we should know that we will use(rather the only one available) the java API JSR82.

For information regarding device compatibility , minimum requirements , requirements for application

development and lots more you can go through this

link:-http://developers.sun.com/mobility/midp/articles/bluetooth2

Now let us first go through the code

:-

-import java.io.IOException;

import javax.bluetooth.*;

import javax.bluetooth.DiscoveryListener;

import javax.microedition.lcdui.*;

import javax.microedition.midlet.*;

/**

* @author Vaibhav

*/

public class discover_device extends MIDlet implements CommandListener,DiscoveryListener {

private final List deviceList;

private final Command Exit,Refresh;

private String deviceName;

private DiscoveryAgent agent;

private Alert dialog;

public discover_device()

{

deviceList = new List("List of Devices",List.IMPLICIT); Exit= new Command("Exit",Command.EXIT, 0);

Refresh = new Command("Refresh",Command.SCREEN, 1); deviceList.addCommand(Exit);

deviceList.addCommand(Refresh);

deviceList.setCommandListener(this);

Display.getDisplay(this).setCurrent(deviceList);

}

public void startApp() {

try {

deviceList.deleteAll();

LocalDevice local = LocalDevice.getLocalDevice();

local.setDiscoverable(DiscoveryAgent.GIAC);

deviceName = local.getFriendlyName();

agent = local.getDiscoveryAgent();

}

catch (BluetoothStateException ex) {

ex.printStackTrace();

}

try {

agent.startInquiry(DiscoveryAgent.GIAC, this);

}

catch (BluetoothStateException ex) {

ex.printStackTrace();

}

}

public void pauseApp() {

}

public void destroyApp(boolean unconditional) {

}

public void commandAction(Command c, Displayable d) { if(c==Exit)

{

this.destroyApp(true);

notifyDestroyed();

}

if(c==Refresh){

this.startApp();

}

}

public void deviceDiscovered(RemoteDevice btDevice, DeviceClass cod) {

String deviceaddress = null;

try {

deviceaddress = btDevice.getBluetoothAddress();//btDevice.getFriendlyName(true);

} catch (Exception ex) {

ex.printStackTrace();

}

deviceList.insert(0, deviceaddress , null);

}

public void servicesDiscovered(int transID, ServiceRecord[] servRecord) {

throw new UnsupportedOperationException("Not supported yet.");

}

public void serviceSearchCompleted(int transID, int respCode) {

throw new UnsupportedOperationException("Not supported yet.");

}

public void inquiryCompleted(int discType) {

Alert dialog = null;

if (discType != DiscoveryListener.INQUIRY_COMPLETED) {

dialog = new Alert("Bluetooth Error","The inquiry failed to complete normally",null, AlertType.ERROR); }

else {

dialog = new Alert("Inquiry Completed","The inquiry completed normally", null,AlertType.INFO); }

dialog.setTimeout(500);

Display.getDisplay(this).setCurrent(dialog);

}

}

-First of all we create a list(Display item) on which we will be displaying the searched device (name or address) and on that same list we will add the command to search and exit

This will be our first display item on starting the application

Then the control goes to startApp() function

The very first command deviceList.deleteAll(); deletes all devices from previous search

LocalDevice local = LocalDevice.getLocalDevice();

This command gets the local bluetooth device

local.setDiscoverable(DiscoveryAgent.GIAC);

This command allows the device to be discovered by others

However using local.setDiscoverable(DiscoveryAgent.NOT_DISCOVERABLE);

we can hide our bluetooth (not visible to others but others are visible to us)