First of all... don't redirect me to Bluetooth Chat and I have fully read it.
I have an Android Client which stablishes the connection properly with the server, and what's most I can send text to the server in my pc and show it correctly, but I can't do the opposite action, send a simple string from the server to the client and show it in my android app.
I don't want to implement a chat is just to show how BT communication works between a Java Server and Android Client.
To make it easy:
I send the text at the end of the startServer() method in the server class.
I try to read the text from the server at the beginning of onPause().
**
[Solved] Solution Below
**.
The code is as follows:
Android BT Client:
/*...libraries here...*/
public class ConnectTest extends Activity {
TextView out;
private static final int REQUEST_ENABLE_BT = 1;
private BluetoothAdapter btAdapter = null;
private BluetoothSocket btSocket = null;
private OutputStream outStream = null;
// Well known SPP UUID
private static final UUID MY_UUID =
UUID.fromString("00001101-0000-1000-8000-00805F9B34FB");
// Insert your server's MAC address
private static String address = "00:10:60:AA:B9:B2";
/** Called when the activity is first created. */
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
out = (TextView) findViewById(R.id.out);
out.append("\n...In onCreate()...");
btAdapter = BluetoothAdapter.getDefaultAdapter();
CheckBTState();
}
public void onStart() {
super.onStart();
out.append("\n...In onStart()...");
}
public void onResume() {
super.onResume();
out.append("\n...In onResume...\n...Attempting client connect...");
// Set up a pointer to the remote node using it's address.
BluetoothDevice device = btAdapter.getRemoteDevice(address);
// Two things are needed to make a connection:
// A MAC address, which we got above.
// A Service ID or UUID. In this case we are using the
// UUID for SPP.
try {
btSocket = device.createRfcommSocketToServiceRecord(MY_UUID);
} catch (IOException e) {
AlertBox("Fatal Error", "In onResume() and socket create failed: " + e.getMessage() + ".");
}
// Discovery is resource intensive. Make sure it isn't going on
// when you attempt to connect and pass your message.
btAdapter.cancelDiscovery();
// Establish the connection. This will block until it connects.
try {
btSocket.connect();
out.append("\n...Connection established and data link opened...");
} catch (IOException e) {
try {
btSocket.close();
} catch (IOException e2) {
AlertBox("Fatal Error", "In onResume() and unable to close socket during connection failure" + e2.getMessage() + ".");
}
}
// Create a data stream so we can talk to server.
out.append("\n...Sending message to server...");
String message = "Hello from Android.\n";
out.append("\n\n...The message that we will send to the server is: "+message);
try {
outStream = btSocket.getOutputStream();
} catch (IOException e) {
AlertBox("Fatal Error", "In onResume() and output stream creation failed:" + e.getMessage() + ".");
}
byte[] msgBuffer = message.getBytes();
try {
outStream.write(msgBuffer);
} catch (IOException e) {
String msg = "In onResume() and an exception occurred during write: " + e.getMessage();
if (address.equals("00:00:00:00:00:00"))
msg = msg + ".\n\nUpdate your server address from 00:00:00:00:00:00 to the correct address on line 37 in the java code";
msg = msg + ".\n\nCheck that the SPP UUID: " + MY_UUID.toString() + " exists on server.\n\n";
AlertBox("Fatal Error", msg);
}
}
public void onPause() {
super.onPause();
//out.append("\n...Hello\n");
InputStream inStream;
try {
inStream = btSocket.getInputStream();
BufferedReader bReader=new BufferedReader(new InputStreamReader(inStream));
String lineRead=bReader.readLine();
out.append("\n..."+lineRead+"\n");
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
out.append("\n...In onPause()...");
if (outStream != null) {
try {
outStream.flush();
} catch (IOException e) {
AlertBox("Fatal Error", "In onPause() and failed to flush output stream: " + e.getMessage() + ".");
}
}
try {
btSocket.close();
} catch (IOException e2) {
AlertBox("Fatal Error", "In onPause() and failed to close socket." + e2.getMessage() + ".");
}
}
public void onStop() {
super.onStop();
out.append("\n...In onStop()...");
}
public void onDestroy() {
super.onDestroy();
out.append("\n...In onDestroy()...");
}
private void CheckBTState() {
// Check for Bluetooth support and then check to make sure it is turned on
// Emulator doesn't support Bluetooth and will return null
if(btAdapter==null) {
AlertBox("Fatal Error", "Bluetooth Not supported. Aborting.");
} else {
if (btAdapter.isEnabled()) {
out.append("\n...Bluetooth is enabled...");
} else {
//Prompt user to turn on Bluetooth
Intent enableBtIntent = new Intent(btAdapter.ACTION_REQUEST_ENABLE);
startActivityForResult(enableBtIntent, REQUEST_ENABLE_BT);
}
}
}
public void AlertBox( String title, String message ){
new AlertDialog.Builder(this)
.setTitle( title )
.setMessage( message + " Press OK to exit." )
.setPositiveButton("OK", new OnClickListener() {
public void onClick(DialogInterface arg0, int arg1) {
finish();
}
}).show();
}
}
and the Java BT Server:
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import javax.bluetooth.*;
import javax.microedition.io.*;
/**
* Class that implements an SPP Server which accepts single line of
* message from an SPP client and sends a single line of response to the client.
*/
public class SimpleSPPServer {
//start server
private void startServer() throws IOException{
//Create a UUID for SPP
UUID uuid = new UUID("1101", true);
//Create the servicve url
String connectionString = "btspp://localhost:" + uuid +";name=Sample SPP Server";
//open server url
StreamConnectionNotifier streamConnNotifier = (StreamConnectionNotifier)Connector.open( connectionString );
//Wait for client connection
System.out.println("\nServer Started. Waiting for clients to connect...");
StreamConnection connection=streamConnNotifier.acceptAndOpen();
RemoteDevice dev = RemoteDevice.getRemoteDevice(connection);
System.out.println("Remote device address: "+dev.getBluetoothAddress());
System.out.println("Remote device name: "+dev.getFriendlyName(true));
//read string from spp client
InputStream inStream=connection.openInputStream();
BufferedReader bReader=new BufferedReader(new InputStreamReader(inStream));
String lineRead=bReader.readLine();
System.out.println(lineRead);
//send response to spp client
OutputStream outStream=connection.openOutputStream();
BufferedWriter bWriter=new BufferedWriter(new OutputStreamWriter(outStream));
bWriter.write("Response String from SPP Server\r\n");
/*PrintWriter pWriter=new PrintWriter(new OutputStreamWriter(outStream));
pWriter.write("Response String from SPP Server\r\n");
pWriter.flush();
pWriter.close();*/
streamConnNotifier.close();
}
public static void main(String[] args) throws IOException {
//display local device address and name
LocalDevice localDevice = LocalDevice.getLocalDevice();
System.out.println("Address: "+localDevice.getBluetoothAddress());
System.out.println("Name: "+localDevice.getFriendlyName());
SimpleSPPServer sampleSPPServer=new SimpleSPPServer();
sampleSPPServer.startServer();
}
}
Solution: It's just a small change in the server side. I don't know why but instead of using BufferedWrite to write in the socket, we need to use PrinterWriter to do so. I add that piece of code modified:
BT Server:
....
//read string from spp client
InputStream inStream=connection.openInputStream();
BufferedReader bReader=new BufferedReader(new InputStreamReader(inStream));
String lineRead=bReader.readLine();
System.out.println(lineRead);
//send response to spp client
OutputStream outStream=connection.openOutputStream();
PrintWriter pWriter=new PrintWriter(new OutputStreamWriter(outStream));
pWriter.write("Response String from SPP Server\r\n");
pWriter.flush();
pWriter.close();
streamConnNotifier.close();
...