Question

我的活动中有几个标签，其中一个是搜索蓝牙设备并在列表视图中显示。但我有一个奇怪的问题，当我第一次点击蓝牙标签时，它不会开始发送，但是当我点击任何其他标签后回来。搜索开始并显示蓝牙设备列表。我无法弄清楚它为什么会发生......任何帮助

第一次永远不会进入OnRecieve

分享代码段

public class BluetoothSettings extends Activity {

@Override
protected void onCreate(Bundle savedInstanceState) {
    requestWindowFeature(Window.FEATURE_NO_TITLE);
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_bluetooth_settings);

    listview = (ListView) findViewById(R.id.listbt);
    txtgeo = (TextView) findViewById(R.id.txtbt);
    progress = (ProgressBar) findViewById(R.id.progressbtBar);
    wait_msg = (TextView) findViewById(R.id.txt_wait_msg);

}
@Override protected void onPause()
{
    bluetooth.cancelDiscovery();
    if(bReceiver != null) {
        bReceiver = null;
    }
    super.onPause();
    Log.d(TAG, "onPause");
}


@Override protected void onResume()
{
    super.onResume();
    if(setBt != null){
        setBt.clear();
        listview.setAdapter(null);
    }
    bluetooth.enable();
    progress.setVisibility(View.VISIBLE);
    wait_msg.setVisibility(View.VISIBLE);
    bluetooth = BluetoothAdapter.getDefaultAdapter();
    IntentFilter filter = new IntentFilter();
    filter.addAction(BluetoothDevice.ACTION_FOUND);
    filter.addAction(BluetoothAdapter.ACTION_DISCOVERY_FINISHED);
    filter.addAction(BluetoothAdapter.ACTION_DISCOVERY_STARTED);
    bReceiver = new BluetoothReceiver();
    registerReceiver(bReceiver, filter);
    bluetooth.startDiscovery();
    if(!bluetooth.isEnabled()) {
        shouldTurnoffBt = true;
    }
    Log.d(TAG, "onResume");
}

@Override protected void onStart()
{
    super.onStart();
    Log.d(TAG, "onStart");
}

@Override protected void onStop() {
    super.onStop();
    Log.d(TAG, "onStop");
}

class BluetoothReceiver extends BroadcastReceiver
{
    public void onReceive(Context context, Intent intent)
    {
        action = intent.getAction();
        Log.d(TAG, "SDSDSSSSSSSSSS ");
        if(BluetoothAdapter.ACTION_DISCOVERY_STARTED.equals(action))
        {
            Log.d(TAG, "dkidkididididididi #1 ");
            txtgeo.setVisibility(View.INVISIBLE);
        }
        if(BluetoothDevice.ACTION_FOUND.equals(action))
        {
            Log.d(TAG, "dkidkididididididi #2 ");
            BluetoothDevice device = intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);
            int rssi = intent.getShortExtra(BluetoothDevice.EXTRA_RSSI,Short.MIN_VALUE);
            setBt.add(new Property(device.getName(), device.getAddress(), rssi));
        }

        if(BluetoothAdapter.ACTION_DISCOVERY_FINISHED.equals(action))
        {
            BluetoothSettings.this.runOnUiThread(new Runnable() {
                @Override
                public void run() {
                    progress.setVisibility(View.INVISIBLE);
                    wait_msg.setVisibility(View.GONE);
                    if(shouldTurnoffBt)
                        bluetooth.disable();
                    if(setBt != null && setBt.size() > 0){
                       Log.d(TAG, "dkidkididididididi #3 ");
                        ArrayList<Property> lt = new ArrayList<Property>(setBt);
                        esWiFiSettings.settingSort(lt);
                        btAdapter = new btAdapter(BluetoothSettings.this, R.layout.bt_adapter, lt, "Bluetooth");
                        listview.setAdapter(btAdapter);
                        bluetooth.cancelDiscovery();
                    } else {
                        txtgeo.setVisibility(View.VISIBLE);
                        txtgeo.setText("No Bluetooth Device Found");
                    }
                }
            });
        }
    }

}
private BluetoothReceiver bReceiver;
public HashSet<Property> setBt = new HashSet<Property>();
String action;
boolean shouldTurnoffBt = false;
ListView listview;
BluetoothAdapter bluetooth;
private TextView txtgeo, wait_msg;
private ProgressBar progress;

Answer 1

我只能猜测，但检查您的代码和BluetoothAdapter JavaDoc很可能您的bluetooth.startDiscovery()调用返回false。来自JavaDoc：

如果蓝牙状态不是STATE_ON，则此API将返回false。打开蓝牙后，请等待带有STATE_ON的ACTION_STATE_CHANGED以获取更新的值。

检查返回值，并在确定启用蓝牙时才启动发现。如果bluetooth.isEnabled()返回false，则必须激活蓝牙（就像你已经做过的那样）但是你应该在接收器中捕获引用的ACTION_STATE_CHANGED - 事件（因此在你调用{{1}之前注册接收器}）。

另外，请勿忘记在onPause或onStop上拨打unregisterReceiver(bReceiver)。如果您没有向我们展示更多代码，则行

if（！bluetooth.isEnabled（））{ shouldTurnoffBt = true; }

对你所描述的行为看起来很可疑;-) 请注意，蓝牙发现非常重要，最多需要12秒。

这个BroadcastReceiver的东西可能很棘手。我刚才为Blaubot写了一个包装类。请检查此代码：BlaubotBluetoothDeviceDiscoveryReceiver（您还需要this interface）。或者，如果您只想连接多个Android设备，只需使用NFC-Beacon use Blaubot即可完全消除发现的需要。

蓝牙发现不是第一次点击开始

1 个答案: