I've been following these two posts SPP Server and Client and this stackoverflow post. I have the server running on a Linux VM and the Android app running on a Samsung Galaxy S6. When I run the server code in Intellij, it says:
"Server Started. Waiting for clients to connect".
When I run the Android app, I get the following Alert box saying:
"Fatal Error. In OnResume()and an exception occurred during write: socket closed. Check that the SPP UUID: 00001101-0000-1000-8000-00805F9B34FB exists on server. Press OK to exit.
Why is this happening and how can I resolve it so the server will connect and receive a string from the Android app?
SPP Server Code:
import java.io.BufferedReader;
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.*;
public class SampleSPPServer {
//start server
private void startServer() throws IOException{
//Create a UUID for SPP
UUID uuid = new UUID("0000110100001000800000805F9B34FB", false);
//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();
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());
SampleSPPServer sampleSPPServer=new SampleSPPServer();
sampleSPPServer.startServer();
}
}
Android Client Code:
import android.bluetooth.BluetoothAdapter;
import android.bluetooth.BluetoothDevice;
import android.bluetooth.BluetoothSocket;
import android.content.DialogInterface;
import android.content.Intent;
import android.support.v7.app.AlertDialog;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.widget.TextView;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.util.UUID;
public class BluetoothClient extends AppCompatActivity {
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.activity_bluetooth_client);
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 DialogInterface.OnClickListener() {
public void onClick(DialogInterface arg0, int arg1) {
finish();
}
}).show();
}
}
Android Studio Logcat:
android.view.WindowLeaked: Activity com.example.toby.btclientapp.BluetoothClient has leaked window com.android.internal.policy.PhoneWindow$DecorView{b73d40d V.E...... R.....I. 0,0-1368,1249} that was originally added here
at android.view.ViewRootImpl.<init>(ViewRootImpl.java:569)
at android.view.WindowManagerGlobal.addView(WindowManagerGlobal.java:326)
at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:91)
at android.app.Dialog.show(Dialog.java:350)
at android.support.v7.app.AlertDialog$Builder.show(AlertDialog.java:955)
at com.example.toby.btclientapp.BluetoothClient.AlertBox(BluetoothClient.java:181)
at com.example.toby.btclientapp.BluetoothClient.onResume(BluetoothClient.java:107)
at android.app.Instrumentation.callActivityOnResume(Instrumentation.java:1286)
at android.app.Activity.performResume(Activity.java:6987)
at android.app.ActivityThread.performResumeActivity(ActivityThread.java:4145)
at android.app.ActivityThread.handleResumeActivity(ActivityThread.java:4250)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3361)
at android.app.ActivityThread.access$1100(ActivityThread.java:222)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1795)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:158)
at android.app.ActivityThread.main(ActivityThread.java:7229)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1230)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1120)
07-26 13:09:21.574 3857-3857/? E/WindowManager: android.view.WindowLeaked: Activity com.example.toby.btclientapp.BluetoothClient has leaked window com.android.internal.policy.PhoneWindow$DecorView{9723488 V.E...... R....... 0,0-1368,1249} that was originally added here
at android.view.ViewRootImpl.<init>(ViewRootImpl.java:569)
at android.view.WindowManagerGlobal.addView(WindowManagerGlobal.java:326)
at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:91)
at android.app.Dialog.show(Dialog.java:350)
at android.support.v7.app.AlertDialog$Builder.show(AlertDialog.java:955)
at com.example.toby.btclientapp.BluetoothClient.AlertBox(BluetoothClient.java:181)
at com.example.toby.btclientapp.BluetoothClient.onResume(BluetoothClient.java:107)
at android.app.Instrumentation.callActivityOnResume(Instrumentation.java:1286)
at android.app.Activity.performResume(Activity.java:6987)
at android.app.ActivityThread.performResumeActivity(ActivityThread.java:4145)
at android.app.ActivityThread.handleResumeActivity(ActivityThread.java:4250)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1839)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:158)
at android.app.ActivityThread.main(ActivityThread.java:7229)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1230)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1120)
07-26 13:09:21.574 3857-3857/? E/WindowManager: android.view.WindowLeaked: Activity com.example.toby.btclientapp.BluetoothClient has leaked window com.android.internal.policy.PhoneWindow$DecorView{cea821b V.E...... R....... 0,0-1368,799} that was originally added here
at android.view.ViewRootImpl.<init>(ViewRootImpl.java:569)
at android.view.WindowManagerGlobal.addView(WindowManagerGlobal.java:326)
at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:91)
at android.app.Dialog.show(Dialog.java:350)
at android.support.v7.app.AlertDialog$Builder.show(AlertDialog.java:955)
at com.example.toby.btclientapp.BluetoothClient.AlertBox(BluetoothClient.java:181)
at com.example.toby.btclientapp.BluetoothClient.onPause(BluetoothClient.java:135)
at android.app.Activity.performPause(Activity.java:7033)
at android.app.Instrumentation.callActivityOnPause(Instrumentation.java:1339)
at android.app.ActivityThread.performPauseActivity(ActivityThread.java:4577)
at android.app.ActivityThread.performPauseActivity(ActivityThread.java:4550)
at android.app.ActivityThread.handlePauseActivity(ActivityThread.java:4525)
at android.app.ActivityThread.access$1300(ActivityThread.java:222)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1813)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:158)
at android.app.ActivityThread.main(ActivityThread.java:7229)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1230)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1120)
I needed to change the MAC address of the Bluetooth adapter. It works now.