我正在android studio中使用Java开发第一个蓝牙应用程序。它是一个国际象棋游戏，我想将当前的场地信息从一个设备发送到另一个设备。我查看了https://developer.android.com/guide/topics/connectivity/bluetooth.html处的概述和介绍，在我想连接两个设备之前，它的工作效果很好。我可以在listView中显示另一个设备，当我单击listView中的项目时，我想连接两个设备，但是两个设备都崩溃了，并且出现此异常：
java.lang.RuntimeException: Can't create handler inside thread that has not called Looper.prepare()
我已经将初始化从Service类移动到Manager类，也将其移动到Activity，因为我认为我需要在UI线程中进行初始化，但无济于事
这是Bluetoothmanager-Class女巫启动蓝牙并启动接收器以监听设备
public class BluetoothManager extends Observable {
private BluetoothAdapter adapter;
private Context context;
private UUID uuid;
private BluetoothService service;
private BluetoothDevice connectedDevice;
public BluetoothManager(Context c){
adapter = BluetoothAdapter.getDefaultAdapter();
context = c;
uuid = UUID.fromString("1c0bbc73-ae02-4272-b528-752b6b0977c4");
}
public boolean supportBluetooth(){
if(adapter == null){
return false;
}else{
return true;
}
}
public void isEnabled(){
if(!adapter.isEnabled()){
Intent intent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
((Activity) context).startActivityForResult(intent, 1);
//registerReceiver();
}
enableDiscoverability();
}
private BroadcastReceiver receiver = new BroadcastReceiver() {
@Override
public void onReceive(Context context, Intent intent) {
String action = intent.getAction();
if(action.equals(BluetoothDevice.ACTION_FOUND)){
setChanged();
notifyObservers(intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE));
}
}
};
public BroadcastReceiver getReceiver() {
return receiver;
}
public void enableDiscoverability(){
Intent intent = new Intent(BluetoothAdapter.ACTION_REQUEST_DISCOVERABLE);
context.startActivity(intent);
AcceptThread acceptThread = new AcceptThread();
acceptThread.start();
}
public Set<BluetoothDevice> getPaired(){
return adapter.getBondedDevices();
}
public void manageSocket(BluetoothSocket socket){
Handler handler = new Handler(){
@Override
public void handleMessage(Message msg) {
super.handleMessage(msg);
System.out.println(msg.toString());
}
};
service = new BluetoothService(socket, handler);
service.write();
}
public void connect(BluetoothDevice device){
ConnectThread thread = new ConnectThread(device);
thread.start();
}
private class AcceptThread extends Thread{
private final BluetoothServerSocket serverSocket;
private AcceptThread() {
BluetoothServerSocket tmp = null;
try{
tmp = adapter.listenUsingInsecureRfcommWithServiceRecord(context.getString(R.string.app_name), uuid);
}catch (IOException e){
System.out.println("FAILED");
}
serverSocket = tmp;
}
@Override
public void run() {
BluetoothSocket socket = null;
while (true){
try{
socket = serverSocket.accept();
if(socket != null){
manageSocket(socket);
serverSocket.close();
break;
}
}catch (IOException e){
System.out.println("FAILED");
break;
}
}
}
public void cancel(){
try {
serverSocket.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
private class ConnectThread extends Thread {
private final BluetoothSocket socket;
private final BluetoothDevice device;
public ConnectThread(BluetoothDevice mdevice) {
BluetoothSocket tmp = null;
device = mdevice;
try {
tmp = device.createRfcommSocketToServiceRecord(uuid);
} catch (IOException e) {
System.out.println("FAILED");
}
socket = tmp;
}
public void run() {
adapter.cancelDiscovery();
try {
socket.connect();
} catch (IOException connectException) {
// Unable to connect; close the socket and return.
try {
socket.close();
} catch (IOException closeException) {
System.out.println("FAILED");
}
return;
}
// The connection attempt succeeded. Perform work associated with
// the connection in a separate thread.
manageSocket(socket);
}
// Closes the client socket and causes the thread to finish.
public void cancel() {
try {
socket.close();
} catch (IOException e) {
System.out.println("FAILED");
}
}
}
}
这是我要在设备之间传输数据的BluetoothService-Class：
public class BluetoothService {
private static final String TAG = "MY_APP_DEBUG_TAG";
private Handler handler;
private BluetoothSocket socket;
private ConnectedThread thread;
public BluetoothService(BluetoothSocket socket, Handler handler){
this.socket = socket;
this.handler = handler;
thread = new ConnectedThread();
thread.start();
}
private interface MessageConstants {
public static final int MESSAGE_READ = 0;
public static final int MESSAGE_WRITE = 1;
public static final int MESSAGE_TOAST = 2;
}
private class ConnectedThread extends Thread {
private final BluetoothSocket mmSocket;
private final InputStream mmInStream;
private final OutputStream mmOutStream;
private byte[] mmBuffer;
public ConnectedThread() {
mmSocket = socket;
InputStream tmpIn = null;
OutputStream tmpOut = null;
try {
tmpIn = socket.getInputStream();
} catch (IOException e) {
Log.e(TAG, "Error occurred when creating input stream", e);
}
try {
tmpOut = socket.getOutputStream();
} catch (IOException e) {
Log.e(TAG, "Error occurred when creating output stream", e);
}
mmInStream = tmpIn;
mmOutStream = tmpOut;
}
public void run() {
mmBuffer = new byte[1024];
int numBytes;
while (true) {
try {
numBytes = mmInStream.read(mmBuffer);
Message readMsg = handler.obtainMessage( MessageConstants.MESSAGE_READ, numBytes, -1,mmBuffer);
readMsg.sendToTarget();
} catch (IOException e) {
Log.d(TAG, "Input stream was disconnected", e);
break;
}
}
}
public void write(byte[] bytes) {
try {
mmOutStream.write(bytes);
Message writtenMsg = handler.obtainMessage(MessageConstants.MESSAGE_WRITE, -1, -1, mmBuffer);
writtenMsg.sendToTarget();
} catch (IOException e) {
Log.e(TAG, "Error occurred when sending data", e);
// Send a failure message back to the activity.
Message writeErrorMsg = handler.obtainMessage(MessageConstants.MESSAGE_TOAST);
Bundle bundle = new Bundle();
bundle.putString("toast", "Couldn't send data to the other device");
writeErrorMsg.setData(bundle);
handler.sendMessage(writeErrorMsg);
}
}
public void cancel() {
try {
mmSocket.close();
} catch (IOException e) {
Log.e(TAG, "Could not close the connect socket", e);
}
}
}
public Handler getHandler() {
return handler;
}
public void write(){
String s = "HALLO WELT";
byte[] bytes = s.getBytes();
thread.write(bytes);
}
public void setHandler(Handler handler) {
this.handler = handler;
}
}
这是MainActivtiy，我在其中创建对象
public class ChessActivity extends AppCompatActivity implements Observer {
private RelativeLayout layout;
private Game game;
private ChessCanvas canvas;
private BluetoothManager manager;
private List<BluetoothDevice> devices;
private ListView deviceList;
private DeviceListAdapter adapter;
private TextView status;
@Override
protected void onCreate(@Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_chess);
Persister.init(this);
layout = findViewById(R.id.layout);
deviceList = findViewById(R.id.deviceList);
status = findViewById(R.id.status);
devices = new ArrayList<>();
adapter = new DeviceListAdapter(this, android.R.layout.simple_list_item_1, (List) devices);
deviceList.setAdapter(adapter);
canvas = new ChessCanvas(this);
layout.addView(canvas);
game = new Game(canvas);
deviceList.setOnItemClickListener(new AdapterView.OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
manager.connect((BluetoothDevice) parent.getItemAtPosition(position));
}
});
canvas.setOnTouchListener(new View.OnTouchListener() {
@Override
public boolean onTouch(View view, MotionEvent motionEvent) {
if (game.getPoints() == null || game.getPoints().isEmpty() || game.touchedOther(motionEvent)) {
game.getFigure(motionEvent);
} else {
game.turn(motionEvent);
}
Persister.persist(game.getField());
game.update();
return false;
}
});
start();
}
private void start() {
startBluetooth();
if(Persister.getGame() == null) {
game.createField();
Persister.setGame(game.getField());
Persister.persist(game.getField());
}else{
game.setField(Persister.getGame());
}
game.update();
}
private void startBluetooth() {
manager = new BluetoothManager(this);
if(manager.supportBluetooth()){
manager.isEnabled();
devices.addAll(manager.getPaired());
registerReceiver(manager.getReceiver(), new IntentFilter(BluetoothDevice.ACTION_FOUND));
}else{
System.out.println("KEIN BLUETOTH");
}
displayBluetoothList();
}
@Override
public void update(Observable o, Object arg) {
BluetoothDevice device = (BluetoothDevice) arg;
devices.add(device);
displayBluetoothList();
}
private void displayBluetoothList() {
adapter.notifyDataSetChanged();
deviceList.setVisibility(View.VISIBLE);
layout.removeView(deviceList);
AlertDialog adb = new AlertDialog.Builder(this).create();
adb.setTitle("Bluetooth Geräte");
adb.setView(deviceList);
adb.show();
}
@Override
protected void onPause() {
super.onPause();
unregisterReceiver(manager.getReceiver());
}
}
我应该在哪里创建并初始化处理程序对象？感谢您的帮助！
错误消息并不表示您必须移动代码。它说您必须在创建新处理程序之前调用Looper.prepare()。