【发布时间】：2015-06-17 15:04:14
【问题描述】：
每次更改位置时，我都会尝试通过蓝牙将计算出的方位从 android 设备发送到 Arduino。尝试使用 outPutStream 时，应用程序总是崩溃。代码如下：
public class Location_Informaion extends MainActivity implements LocationListener {
private static final String TAG = "bluetooth1";
TextView desiredDest, currentLatitude, currentLongitude, Distance, Bearing, txtArduino;
private LocationManager locationManager;
String provider, message;
private Location location;
double desLatVal, desLonVal, pi;
private BluetoothAdapter btAdapter = null;
private BluetoothSocket btSocket = null;
private OutputStream outStream = null;
private static final UUID MY_UUID = UUID.fromString("00001101-0000-1000-8000-00805F9B34FB");
private static String macAddress = "30:14:12:02:16:78";
private ConnectedThread mConnectedThread;
Handler h;
final int RECIEVE_MESSAGE = 1; // Status for Handler
private StringBuilder sb = new StringBuilder();
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
pi = 3.14159265359;
setContentView(R.layout.activity_location__informaion);
Bundle extras = getIntent().getExtras();
String desLat = extras.getString("desLat");
String desLon = extras.getString("desLon");
desLatVal = Double.parseDouble(desLat);
desLonVal = Double.parseDouble(desLon);
desiredDest = (TextView) findViewById(R.id.desiredDestination);
desiredDest.setText(desLat + "Lat, " + desLon + "Long.");
message = "180";
currentLatitude = (TextView) findViewById(R.id.currentLat);
currentLongitude = (TextView) findViewById(R.id.currentLon);
txtArduino = (TextView) findViewById(R.id.txtArduino);
Distance = (TextView) findViewById(R.id.Distance);
Bearing = (TextView) findViewById(R.id.Bearing);
LocationManager service = (LocationManager) getSystemService(LOCATION_SERVICE);
boolean enabled = service.isProviderEnabled(LocationManager.GPS_PROVIDER);
if (!enabled) {
Intent intent = new Intent(Settings.ACTION_LOCATION_SOURCE_SETTINGS);
startActivity(intent);
}
locationManager = (LocationManager) getSystemService(LOCATION_SERVICE);
Criteria criteria = new Criteria();
provider = locationManager.getBestProvider(criteria, false);
Location location = locationManager.getLastKnownLocation(provider);
if (location != null) {
System.out.println("Provider" + provider + "has been selected");
currentLatitude.setText("Searching for lock");
currentLongitude.setText("Searching for lock");
onLocationChanged(location);
} else {
currentLatitude.setText("Location is not available");
currentLongitude.setText("Location is not available");
}
h = new Handler() {
public void handleMessage(android.os.Message msg) {
switch (msg.what) {
case RECIEVE_MESSAGE: // if receive massage
byte[] readBuf = (byte[]) msg.obj;
String strIncom = new String(readBuf, 0, msg.arg1); // create string from bytes array
sb.append(strIncom); // append string
int endOfLineIndex = sb.indexOf("\r\n"); // determine the end-of-line
if (endOfLineIndex > 0) { // if end-of-line,
String sbprint = sb.substring(0, endOfLineIndex); // extract string
sb.delete(0, sb.length()); // and clear
txtArduino.setText("Data from Arduino: " + sbprint); // update TextView
}
//Log.d(TAG, "...String:"+ sb.toString() + "Byte:" + msg.arg1 + "...");
break;
}
}
};
btAdapter = BluetoothAdapter.getDefaultAdapter(); // get Bluetooth adapter
checkBTState();
}
private BluetoothSocket createBluetoothSocket(BluetoothDevice device) throws IOException {
if(Build.VERSION.SDK_INT >= 10){
try {
final Method m = device.getClass().getMethod("createInsecureRfcommSocketToServiceRecord", new Class[] { UUID.class });
return (BluetoothSocket) m.invoke(device, MY_UUID);
} catch (Exception e) {
Log.e(TAG, "Could not create Insecure RFComm Connection",e);
}
}
return device.createRfcommSocketToServiceRecord(MY_UUID);
}
public void onResume() {
super.onResume();
locationManager.requestLocationUpdates(provider, 0, 0, this);
Log.d(TAG, "...onResume - try connect...");
BluetoothDevice device = btAdapter.getRemoteDevice(macAddress);
try {
btSocket = createBluetoothSocket(device);
} catch (IOException e) {
errorExit("Fatal Error", "In onResume() and socket create failed: " + e.getMessage() + ".");
}
btAdapter.cancelDiscovery();
Log.d(TAG, "...Connecting...");
try {
btSocket.connect();
Log.d(TAG, "....Connection ok...");
} catch (IOException e) {
try {
btSocket.close();
} catch (IOException e2) {
errorExit("Fatal Error", "In onResume() and unable to close socket during connection failure" + e2.getMessage() + ".");
}
}
Log.d(TAG, "...Create Socket...");
mConnectedThread = new ConnectedThread(btSocket);
mConnectedThread.start();
}
protected void onPause() {
super.onPause();
locationManager.removeUpdates(this);
Log.d(TAG, "...In onPause()...");
try {
btSocket.close();
} catch (IOException e2) {
errorExit("Fatal Error", "In onPause() and failed to close socket." + e2.getMessage() + ".");
}
}
private void checkBTState() {
if(btAdapter==null) {
errorExit("Fatal Error", "Bluetooth not support");
} else {
if (btAdapter.isEnabled()) {
Log.d(TAG, "...Bluetooth ON...");
} else {
//Prompt user to turn on Bluetooth
Intent enableBtIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
startActivityForResult(enableBtIntent, 1);
}
}
}
private void errorExit(String title, String message){
Toast.makeText(getBaseContext(), title + " - " + message, Toast.LENGTH_LONG).show();
finish();
}
private class ConnectedThread extends Thread {
private final InputStream mmInStream;
private final OutputStream mmOutStream;
public ConnectedThread(BluetoothSocket socket) {
InputStream tmpIn = null;
OutputStream tmpOut = null;
try {
tmpIn = socket.getInputStream();
tmpOut = socket.getOutputStream();
} catch (IOException e) { }
mmInStream = tmpIn;
mmOutStream = tmpOut;
}
public void run() {
byte[] buffer = new byte[256];
int bytes;
while (true) {
try {
// Read from the InputStream
bytes = mmInStream.read(buffer);
h.obtainMessage(RECIEVE_MESSAGE, bytes, -1, buffer).sendToTarget();
} catch (IOException e) {
break;
}
}
}
public void write(String message) {
Log.d(TAG, "...Data to send: " + message + "...");
byte[] msgBuffer = message.getBytes();
try {
mmOutStream.write(msgBuffer, 0, msgBuffer.length);
} catch (IOException e) {
Log.d(TAG, "...Error data send: " + e.getMessage() + "...");
}
}
}
@Override
public void onLocationChanged(Location location) {
double lat = (location.getLatitude());
double lon = (location.getLongitude());
currentLatitude.setText(String.valueOf(lat));
currentLongitude.setText(String.valueOf(lon));
float R = 6371000;
double latRad = lat / (180 / pi);
double desLatRad = desLatVal / (180 * pi);
double changeLat = (desLatVal - lat) / (180 * pi);
double changeLon = (desLonVal - lon) / (180 / pi);
double a = Math.sin(changeLat / 2) * Math.sin(changeLat / 2) +
Math.cos(latRad) * Math.cos(desLatRad) *
Math.sin(changeLon / 2) * Math.sin(changeLon / 2);
double c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1 - a));
double d = R * c / 1000;
String distance = String.valueOf(d);
Distance.setText(distance + "km");
double y = Math.sin(desLonVal - lon) * Math.cos(desLatVal);
double x = Math.cos(lat) * Math.sin(desLatVal) -
Math.sin(lat) * Math.cos(desLatVal) * Math.cos(desLonVal - lon);
double brng = (Math.atan2(y, x)) * 180 / pi;
String bearing = String.valueOf(brng);
Bearing.setText(bearing);
mConnectedThread.write(bearing);
}
@Override
public void onStatusChanged(String provider, int status, Bundle extras) {
}
@Override
public void onProviderEnabled(String provider) {
Toast.makeText(this, "Enable new provider " + provider, Toast.LENGTH_SHORT).show();
}
@Override
public void onProviderDisabled(String provider) {
Toast.makeText(this, "Disabled provider " + provider, Toast.LENGTH_SHORT).show();
}
}
任何帮助将不胜感激。
06-17 16:34:35.930 11800-11818/com.example.biggus.system_4 I/OpenGLRenderer﹕初始化的 EGL，版本 1.4 06-17 16:34:35.950 11800-11818/com.example.biggus.system_4 I/OpenGLRenderer：为上下文启用了 HWUI 保护，&this =0xb3922088，&mEglDisplay = 1，&mEglConfig = 8 06-17 16:34:35.950 11800-11818/com.example.biggus.system_4 D/OpenGLRenderer: 启用调试模式 0 06-17 16:34:36.090 11800-11800/com.example.biggus.system_4 I/时间线：时间线：Activity_idle id：android.os.BinderProxy@346384f1 time:13135175 06-17 16:34:37.870 11800-11800/com.example.biggus.system_4 D/ViewRootImpl: ViewPostImeInputStage ACTION_DOWN 06-17 16:34:40.740 11800-11800/com.example.biggus.system_4 D/ViewRootImpl: ViewPostImeInputStage ACTION_DOWN 06-17 16:34:43.850 11800-11800/com.example.biggus.system_4 D/ViewRootImpl: ViewPostImeInputStage ACTION_DOWN 06-17 16:34:43.930 11800-11800/com.example.biggus.system_4 I/时间线：时间线：Activity_launch_request id:com.example.biggus.system_4 time:13143016 06-17 16:34:44.060 11800-11800/com.example.biggus.system_4 I/System.out: Providergpshas 已被选择 06-17 16:34:44.070 11800-11800/com.example.biggus.system_4 D/AndroidRuntime: 关闭虚拟机 06-17 16:34:44.070 11800-11800/com.example.biggus.system_4 E/AndroidRuntime：致命异常：主要 进程：com.example.biggus.system_4，PID：11800 java.lang.RuntimeException：无法启动活动 ComponentInfo{com.example.biggus.system_4/com.example.biggus.system_4.Location_Informaion}：java.lang.NullPointerException：尝试调用虚拟方法'void com.example.biggus。 system_4.Location_Informaion$ConnectedThread.write(java.lang.String)' 在空对象引用上 在 android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2658) 在 android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2725) 在 android.app.ActivityThread.access$900(ActivityThread.java:172) 在 android.app.ActivityThread$H.handleMessage(ActivityThread.java:1422) 在 android.os.Handler.dispatchMessage(Handler.java:102) 在 android.os.Looper.loop(Looper.java:145) 在 android.app.ActivityThread.main(ActivityThread.java:5834) 在 java.lang.reflect.Method.invoke（本机方法） 在 java.lang.reflect.Method.invoke(Method.java:372) 在 com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1388) 在 com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1183) 原因：java.lang.NullPointerException：尝试在空对象引用上调用虚拟方法 'void com.example.biggus.system_4.Location_Informaion$ConnectedThread.write(java.lang.String)' 在 com.example.biggus.system_4.Location_Informaion.onLocationChanged(Location_Informaion.java:283) 在 com.example.biggus.system_4.Location_Informaion.onCreate(Location_Informaion.java:89) 在 android.app.Activity.performCreate(Activity.java:6221) 在 android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1119) 在 android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2611) 在 android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2725) 在 android.app.ActivityThread.access$900(ActivityThread.java:172) 在 android.app.ActivityThread$H.handleMessage(ActivityThread.java:1422) 在 android.os.Handler.dispatchMessage(Handler.java:102) 在 android.os.Looper.loop(Looper.java:145) 在 android.app.ActivityThread.main(ActivityThread.java:5834) 在 java.lang.reflect.Method.invoke（本机方法） 在 java.lang.reflect.Method.invoke(Method.java:372) 在 com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1388) 在 com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1183)
【问题讨论】：
标签： android bluetooth arduino communication