我修改了蓝牙聊天示例，以使其在接收时通过 BT 将短信文本发送到另一台设备。当我尝试从接收器访问 Application 类的 SendMessage 方法时，我得到了 NullPointerException。
MainActivity.java
public class MainActivity extends Activity {
public static MainActivity mThis;
// Layout Views
private TextView mNotificationView;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
if(D) Log.d(TAG, "+++ ON CREATE +++");
// Set up the window layout
setContentView(R.layout.activity_main);
// Get local Bluetooth adapter
mBluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
// If the adapter is null, then Bluetooth is not supported
if (mBluetoothAdapter == null) {
Toast.makeText(this, "Bluetooth is not available", Toast.LENGTH_LONG).show();
finish();
return;
}
}
@Override
public void onStart() {
super.onStart();
if(D) Log.d(TAG, "++ ON START ++");
// If BT is not on, request that it be enabled.
// setupChat() will then be called during onActivityResult
if (!mBluetoothAdapter.isEnabled()) {
Intent enableIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
startActivityForResult(enableIntent, REQUEST_ENABLE_BT);
// Otherwise, setup the chat session
} else {
if (mChatService == null) setupChat();
}
}
@Override
public synchronized void onResume() {
super.onResume();
if(D) Log.d(TAG, "+ ON RESUME +");
// Performing this check in onResume() covers the case in which BT was
// not enabled during onStart(), so we were paused to enable it...
// onResume() will be called when ACTION_REQUEST_ENABLE activity returns.
if (mChatService != null) {
// Only if the state is STATE_NONE, do we know that we haven't started already
if (mChatService.getState() == BTService.STATE_NONE) {
// Start the Bluetooth chat services
mChatService.start();
}
}
}
private void setupChat() {
mNotificationView = (TextView) findViewById(R.id.notification);
mChatService = new BTService(this, mHandler);
//
// // Initialize the buffer for outgoing messages
mOutStringBuffer = new StringBuffer();
}
@Override
public synchronized void onPause() {
super.onPause();
if(D) Log.d(TAG, "- ON PAUSE -");
}
@Override
public void onStop() {
super.onStop();
if(D) Log.d(TAG, "-- ON STOP ---");
}
@Override
public void onDestroy() {
super.onDestroy();
// Stop the Bluetooth chat services
if (mChatService != null) mChatService.stop();
if(D) Log.d(TAG, "--- ON DESTROY ---");
}
// The Handler that gets information back from the BluetoothChatService
private final Handler mHandler = new Handler() {
@Override
public void handleMessage(Message msg) {
switch (msg.what) {
case MESSAGE_STATE_CHANGE:
if(D) Log.i(TAG, "MESSAGE_STATE_CHANGE: " + msg.arg1);
switch (msg.arg1) {
case BTService.STATE_CONNECTED:
// setStatus(getString(R.string.title_connected_to, mConnectedDeviceName));
// mConversationArrayAdapter.clear();
break;
case BTService.STATE_CONNECTING:
// setStatus(R.string.title_connecting);
break;
case BTService.STATE_LISTEN:
case BTService.STATE_NONE:
// setStatus(R.string.title_not_connected);
break;
}
break;
case MESSAGE_WRITE:
byte[] writeBuf = (byte[]) msg.obj;
// construct a string from the buffer
String writeMessage = new String(writeBuf);
mNotificationView.setText(writeMessage);
// mConversationArrayAdapter.add("Me: " + writeMessage);
break;
case MESSAGE_READ:
byte[] readBuf = (byte[]) msg.obj;
// construct a string from the valid bytes in the buffer
String readMessage = new String(readBuf, 0, msg.arg1);
// mConversationArrayAdapter.add(mConnectedDeviceName+": " + readMessage);
break;
case MESSAGE_DEVICE_NAME:
// save the connected device's name
mConnectedDeviceName = msg.getData().getString(DEVICE_NAME);
Toast.makeText(getApplicationContext(), "Connected to "
+ mConnectedDeviceName, Toast.LENGTH_SHORT).show();
break;
case MESSAGE_TOAST:
Toast.makeText(getApplicationContext(), msg.getData().getString(TOAST),
Toast.LENGTH_SHORT).show();
break;
}
}
};
public void onActivityResult(int requestCode, int resultCode, Intent data) {
if(D) Log.d(TAG, "onActivityResult " + resultCode);
switch (requestCode) {
case REQUEST_CONNECT_DEVICE_SECURE:
// When DeviceListActivity returns with a device to connect
if (resultCode == Activity.RESULT_OK) {
connectDevice(data, true);
}
break;
case REQUEST_CONNECT_DEVICE_INSECURE:
// When DeviceListActivity returns with a device to connect
if (resultCode == Activity.RESULT_OK) {
connectDevice(data, false);
}
break;
case REQUEST_ENABLE_BT:
// When the request to enable Bluetooth returns
if (resultCode == Activity.RESULT_OK) {
// Bluetooth is now enabled, so set up a chat session
// setupChat();
} else {
// User did not enable Bluetooth or an error occurred
Log.d(TAG, "BT not enabled");
Toast.makeText(this, R.string.bt_not_enabled_leaving, Toast.LENGTH_SHORT).show();
finish();
}
}
}
private void connectDevice(Intent data, boolean secure) {
String address = "00:15:FF:F3:C6:8A";
BluetoothDevice device = mBluetoothAdapter.getRemoteDevice(address);
mChatService.connect(device, true);
}
}
BTService.java
public class BTService {
// Unique UUID for this application
private static final UUID MY_UUID = UUID
.fromString("00001101-0000-1000-8000-00805F9B34FB");
// Member fields
private final BluetoothAdapter mAdapter;
private final Handler mHandler;
private AcceptThread mSecureAcceptThread;
private AcceptThread mInsecureAcceptThread;
private ConnectThread mConnectThread;
private ConnectedThread mConnectedThread;
private int mState;
// Constants that indicate the current connection state
public static final int STATE_NONE = 0; // we're doing nothing
public static final int STATE_LISTEN = 1; // now listening for incoming connections
public static final int STATE_CONNECTING = 2; // now initiating an outgoing connection
public static final int STATE_CONNECTED = 3; // now connected to a remote device
public BTService(Context context, Handler handler) {
mAdapter = BluetoothAdapter.getDefaultAdapter();
mState = STATE_NONE;
mHandler = handler;
}
private synchronized void setState(int state) {
if (D) Log.d(TAG, "setState() " + mState + " -> " + state);
mState = state;
// Give the new state to the Handler so the UI Activity can update
mHandler.obtainMessage(MainActivity.MESSAGE_STATE_CHANGE, state, -1).sendToTarget();
}
public synchronized int getState() {
return mState;
}
public synchronized void start() {
if (D) Log.d(TAG, "start");
// Cancel any thread attempting to make a connection
if (mConnectThread != null) {mConnectThread.cancel(); mConnectThread = null;}
// Cancel any thread currently running a connection
if (mConnectedThread != null) {mConnectedThread.cancel(); mConnectedThread = null;}
setState(STATE_LISTEN);
// Start the thread to listen on a BluetoothServerSocket
if (mSecureAcceptThread == null) {
mSecureAcceptThread = new AcceptThread(true);
mSecureAcceptThread.start();
}
if (mInsecureAcceptThread == null) {
mInsecureAcceptThread = new AcceptThread(false);
mInsecureAcceptThread.start();
}
}
public synchronized void connect(BluetoothDevice device, boolean secure) {
if (D) Log.d(TAG, "connect to: " + device);
// Cancel any thread attempting to make a connection
if (mState == STATE_CONNECTING) {
if (mConnectThread != null) {mConnectThread.cancel(); mConnectThread = null;}
}
// Cancel any thread currently running a connection
if (mConnectedThread != null) {mConnectedThread.cancel(); mConnectedThread = null;}
// Start the thread to connect with the given device
mConnectThread = new ConnectThread(device, secure);
mConnectThread.start();
setState(STATE_CONNECTING);
}
/**
* Start the ConnectedThread to begin managing a Bluetooth connection
* @param socket The BluetoothSocket on which the connection was made
* @param device The BluetoothDevice that has been connected
*/
public synchronized void connected(BluetoothSocket socket, BluetoothDevice
device, final String socketType) {
if (D) Log.d(TAG, "connected, Socket Type:" + socketType);
// Cancel the thread that completed the connection
if (mConnectThread != null) {mConnectThread.cancel(); mConnectThread = null;}
// Cancel any thread currently running a connection
if (mConnectedThread != null) {mConnectedThread.cancel(); mConnectedThread = null;}
// Cancel the accept thread because we only want to connect to one device
if (mSecureAcceptThread != null) {
mSecureAcceptThread.cancel();
mSecureAcceptThread = null;
}
if (mInsecureAcceptThread != null) {
mInsecureAcceptThread.cancel();
mInsecureAcceptThread = null;
}
// Start the thread to manage the connection and perform transmissions
mConnectedThread = new ConnectedThread(socket, socketType);
mConnectedThread.start();
// Send the name of the connected device back to the UI Activity
Message msg = mHandler.obtainMessage(MainActivity.MESSAGE_DEVICE_NAME);
Bundle bundle = new Bundle();
bundle.putString(MainActivity.DEVICE_NAME, device.getName());
msg.setData(bundle);
mHandler.sendMessage(msg);
setState(STATE_CONNECTED);
}
/**
* Stop all threads
*/
public synchronized void stop() {
if (D) Log.d(TAG, "stop");
if (mConnectThread != null) {
mConnectThread.cancel();
mConnectThread = null;
}
if (mConnectedThread != null) {
mConnectedThread.cancel();
mConnectedThread = null;
}
if (mSecureAcceptThread != null) {
mSecureAcceptThread.cancel();
mSecureAcceptThread = null;
}
if (mInsecureAcceptThread != null) {
mInsecureAcceptThread.cancel();
mInsecureAcceptThread = null;
}
setState(STATE_NONE);
}
/**
* Write to the ConnectedThread in an unsynchronized manner
* @param out The bytes to write
* @see ConnectedThread#write(byte[])
*/
public void write(byte[] out) {
// Create temporary object
ConnectedThread r;
// Synchronize a copy of the ConnectedThread
synchronized (this) {
if (mState != STATE_CONNECTED) return;
r = mConnectedThread;
}
// Perform the write unsynchronized
r.write(out);
}
/**
* Indicate that the connection attempt failed and notify the UI Activity.
*/
private void connectionFailed() {
// Send a failure message back to the Activity
Message msg = mHandler.obtainMessage(MainActivity.MESSAGE_TOAST);
Bundle bundle = new Bundle();
bundle.putString(MainActivity.TOAST, "Unable to connect device");
msg.setData(bundle);
mHandler.sendMessage(msg);
// Start the service over to restart listening mode
BTService.this.start();
}
/**
* Indicate that the connection was lost and notify the UI Activity.
*/
private void connectionLost() {
// Send a failure message back to the Activity
Message msg = mHandler.obtainMessage(MainActivity.MESSAGE_TOAST);
Bundle bundle = new Bundle();
bundle.putString(MainActivity.TOAST, "Device connection was lost");
msg.setData(bundle);
mHandler.sendMessage(msg);
// Start the service over to restart listening mode
BTService.this.start();
}
/**
* This thread runs while listening for incoming connections. It behaves
* like a server-side client. It runs until a connection is accepted
* (or until cancelled).
*/
private class AcceptThread extends Thread {
// The local server socket
private final BluetoothServerSocket mmServerSocket;
private String mSocketType;
public AcceptThread(boolean secure) {
BluetoothServerSocket tmp = null;
mSocketType = secure ? "Secure":"Insecure";
// Create a new listening server socket
try {
if (secure) {
tmp = mAdapter.listenUsingRfcommWithServiceRecord(NAME_SECURE,
MY_UUID);
} else {
tmp = mAdapter.listenUsingInsecureRfcommWithServiceRecord(
NAME_INSECURE, MY_UUID);
}
} catch (IOException e) {
Log.d(TAG, "Socket Type: " + mSocketType + "listen() failed", e);
}
mmServerSocket = tmp;
}
public void run() {
if (D) Log.d(TAG, "Socket Type: " + mSocketType +
"BEGIN mAcceptThread" + this);
setName("AcceptThread" + mSocketType);
BluetoothSocket socket = null;
// Listen to the server socket if we're not connected
while (mState != STATE_CONNECTED) {
try {
// This is a blocking call and will only return on a
// successful connection or an exception
socket = mmServerSocket.accept();
} catch (IOException e) {
Log.d(TAG, "Socket Type: " + mSocketType + "accept() failed", e);
break;
}
// If a connection was accepted
if (socket != null) {
synchronized (BTService.this) {
switch (mState) {
case STATE_LISTEN:
case STATE_CONNECTING:
// Situation normal. Start the connected thread.
connected(socket, socket.getRemoteDevice(),
mSocketType);
break;
case STATE_NONE:
case STATE_CONNECTED:
// Either not ready or already connected. Terminate new socket.
try {
socket.close();
} catch (IOException e) {
Log.d(TAG, "Could not close unwanted socket", e);
}
break;
}
}
}
}
if (D) Log.i(TAG, "END mAcceptThread, socket Type: " + mSocketType);
}
public void cancel() {
if (D) Log.d(TAG, "Socket Type" + mSocketType + "cancel " + this);
try {
mmServerSocket.close();
} catch (IOException e) {
Log.d(TAG, "Socket Type" + mSocketType + "close() of server failed", e);
}
}
}
/**
* This thread runs while attempting to make an outgoing connection
* with a device. It runs straight through; the connection either
* succeeds or fails.
*/
private class ConnectThread extends Thread {
private final BluetoothSocket mmSocket;
private final BluetoothDevice mmDevice;
private String mSocketType;
public ConnectThread(BluetoothDevice device, boolean secure) {
mmDevice = device;
BluetoothSocket tmp = null;
mSocketType = secure ? "Secure" : "Insecure";
// Get a BluetoothSocket for a connection with the
// given BluetoothDevice
try {
if (secure) {
tmp = device.createRfcommSocketToServiceRecord(
MY_UUID);
} else {
tmp = device.createInsecureRfcommSocketToServiceRecord(
MY_UUID);
}
} catch (IOException e) {
Log.d(TAG, "Socket Type: " + mSocketType + "create() failed", e);
}
mmSocket = tmp;
}
public void run() {
Log.i(TAG, "BEGIN mConnectThread SocketType:" + mSocketType);
setName("ConnectThread" + mSocketType);
// Always cancel discovery because it will slow down a connection
mAdapter.cancelDiscovery();
// Make a connection to the BluetoothSocket
try {
// This is a blocking call and will only return on a
// successful connection or an exception
mmSocket.connect();
} catch (IOException e) {
// Close the socket
try {
mmSocket.close();
} catch (IOException e2) {
Log.d(TAG, "unable to close() " + mSocketType +
" socket during connection failure", e2);
}
connectionFailed();
return;
}
// Reset the ConnectThread because we're done
synchronized (BTService.this) {
mConnectThread = null;
}
// Start the connected thread
connected(mmSocket, mmDevice, mSocketType);
}
public void cancel() {
try {
mmSocket.close();
} catch (IOException e) {
Log.d(TAG, "close() of connect " + mSocketType + " socket failed", e);
}
}
}
/**
* This thread runs during a connection with a remote device.
* It handles all incoming and outgoing transmissions.
*/
private class ConnectedThread extends Thread {
private final BluetoothSocket mmSocket;
private final InputStream mmInStream;
private final OutputStream mmOutStream;
public ConnectedThread(BluetoothSocket socket, String socketType) {
Log.d(TAG, "create ConnectedThread: " + socketType);
mmSocket = socket;
InputStream tmpIn = null;
OutputStream tmpOut = null;
// Get the BluetoothSocket input and output streams
try {
tmpIn = socket.getInputStream();
tmpOut = socket.getOutputStream();
} catch (IOException e) {
Log.d(TAG, "temp sockets not created", e);
}
mmInStream = tmpIn;
mmOutStream = tmpOut;
}
public void run() {
Log.i(TAG, "BEGIN mConnectedThread");
byte[] buffer = new byte[1024];
int bytes;
// Keep listening to the InputStream while connected
while (true) {
try {
// Read from the InputStream
bytes = mmInStream.read(buffer);
// Send the obtained bytes to the UI Activity
mHandler.obtainMessage(MainActivity.MESSAGE_READ, bytes, -1, buffer)
.sendToTarget();
} catch (IOException e) {
Log.d(TAG, "disconnected", e);
connectionLost();
// Start the service over to restart listening mode
BTService.this.start();
break;
}
}
}
/**
* Write to the connected OutStream.
* @param buffer The bytes to write
*/
public void write(byte[] buffer) {
try {
Log.d(TAG, "INSIDE WRITE METHOD");
mmOutStream.write(buffer);
// Share the sent message back to the UI Activity
mHandler.obtainMessage(MainActivity.MESSAGE_WRITE, -1, -1, buffer)
.sendToTarget();
} catch (IOException e) {
Log.d(TAG, "Exception during write", e);
}
}
public void cancel() {
try {
mmSocket.close();
} catch (IOException e) {
Log.d(TAG, "close() of connect socket failed", e);
}
}
}
}
IncomingCallsSMSReceiver.java
public class IncomingCallsSMSReceiver extends BroadcastReceiver {
String prestate, callerno;
private String SENDTAG;
private String SENDMESSAGE;
SMSBT myApp;
private String TAG = "SMSRECEIVER";
@Override
public void onReceive(Context context, Intent arg1) {
// TODO Auto-generated method stub
Bundle extras = arg1.getExtras();
if (arg1.getAction().equals("android.provider.Telephony.SMS_RECEIVED")) {
Log.i("i", "New Message");
if (extras != null) {
Object[] pdus = (Object[]) extras.get("pdus");
for (int i = 0; i < pdus.length; i++) {
SmsMessage currentMessage = SmsMessage
.createFromPdu((byte[]) pdus[i]);
String phoneNumber = currentMessage
.getDisplayOriginatingAddress();
String senderNum = phoneNumber;
String message = currentMessage.getDisplayMessageBody();
Log.i("SmsReceiver", "senderNum: " + senderNum
+ "; message: " + message);
SENDTAG = "S";
SENDMESSAGE = "New SMS :: From :: " + senderNum + " :: "
+ message;
try {
SMSBT.getInstance().sendMessage(SENDTAG, SENDMESSAGE);
Toast.makeText(context.getApplicationContext(),
SENDTAG + SENDMESSAGE, Toast.LENGTH_SHORT)
.show();
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
if (MainActivity.mThis != null) {
((TextView) MainActivity.mThis
.findViewById(R.id.notification))
.setText(SENDTAG + " " + SENDMESSAGE);
} else {
}
}
}
}
}
}
SMSBT.java
public class SMSBT extends Application {
private StringBuffer mOutStringBuffer;
private String TAG = "ABLUETOOTH";
private static SMSBT singleton;
private BTService btService;
// Returns the application instance
public static SMSBT getInstance() {
if (singleton == null) {
singleton = new SMSBT();
}
return singleton;
}
@Override
public void onCreate() {
super.onCreate();
}
void sendMessage(String sendTAG, String sendMessage) {
Log.d(TAG,
"Hooooooorayyyyyyyyyyyyyyyyyyyy INSIDE send message send message send message send message");
//
// if (btService != null) {
// // Only if the state is STATE_NONE, do we know that we haven't
// // started already
// if (btService.getState() == BTService.STATE_NONE) {
// // Start the Bluetooth chat services
// btService.start();
//
// } else if (btService.getState() == BTService.STATE_CONNECTED) {
if (sendMessage.length() > 0) {
// Get the message bytes and tell the BluetoothChatService
// to write
byte[] send = (sendTAG + sendMessage).getBytes();
try {
Log.d(TAG, "TRY TRY TRY BLOCK BLOCK BLOCK");
btService.write(send);
Toast.makeText(getApplicationContext(),
"Transferred to SmartBand", Toast.LENGTH_SHORT)
.show();
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
// Reset out string buffer to zero and clear the edit text
// field
mOutStringBuffer.setLength(0);
if (MainActivity.mThis != null) {
((TextView) MainActivity.mThis
.findViewById(R.id.notification))
.setText(sendMessage);
} else {
Log.i("i", " GGGGGGGOT A NULLLLLLLLLLLL");
}
}
}
// }
// }
}
LOGCAT
TRY TRY TRY BLOCK BLOCK BLOCK
java.lang.NullPointerException
at com.practice.abluetooth.SMSBT.sendMessage(SMSBT.java:50)
at com.practice.abluetooth.IncomingCallsSMSReceiver.onReceive(IncomingCallsSMSReceiver.java:52)
.
.
java.lang.NullPointerException
at com.practice.abluetooth.SMSBT.sendMessage(SMSBT.java:61)
at com.practice.abluetooth.IncomingCallsSMSReceiver.onReceive(IncomingCallsSMSReceiver.java:52)
等待帮助。