Question

我需要以编程方式在Android设备中打开蓝牙并等到它继续进行下一行代码。

我的代码如下

if (!mBluetoothAdapter.isEnabled()) {
                Intent enableBtIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
                ctx.startActivity(enableBtIntent);
}

当这样做时，代码继续从nect行执行，而不必完全等待蓝牙。有什么方法可以解决这个问题吗？我可以添加外观来检查蓝牙是否已打开？

Answer 1

您可以注册BroadcastReceiver以收听BluetoothAdapter上的状态更改。

首先创建一个将监听状态更改的BroadcastReceiver

private final BroadcastReceiver mReceiver = new BroadcastReceiver() {
    @Override
    public void onReceive(Context context, Intent intent) {
        final String action = intent.getAction();

        if (action.equals(BluetoothAdapter.ACTION_STATE_CHANGED)) {
            final int bluetoothState = intent.getIntExtra(BluetoothAdapter.EXTRA_STATE,
                                                BluetoothAdapter.ERROR);
            switch (bluetoothState) {
            case BluetoothAdapter.STATE_ON:
                //Bluethooth is on, now you can perform your tasks
                break;
            }
        }
    }
};

然后注册 BroadcastReceiver创建Activity，以便它可以开始接收事件。

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    //Set a filter to only receive bluetooth state changed events.
    IntentFilter filter = new IntentFilter(BluetoothAdapter.ACTION_STATE_CHANGED);
    registerReceiver(mReceiver, filter);
}

在Activity被销毁时，请记得取消注册听众。

@Override
public void onDestroy() {
    super.onDestroy();
    unregisterReceiver(mReceiver);
}

Answer 2

使用此代码您的清单文件的权限

<uses-permission android:name="android.permission.BLUETOOTH"/>
<uses-permission android:name="android.permission.BLUETOOTH_ADMIN"/>

和代码

if (!mBluetoothAdapter.isEnabled()) {
     Intent enableBtIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
     startActivityForResult(enableBtIntent , 0);
  } else
  {
     Toast.makeText(getApplicationContext(),"Already on", Toast.LENGTH_LONG).show();
  }

@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
super.onActivityResult(requestCode, resultCode, data);
if(resultCode == RESULT_OK){
    Toast.makeText(getApplicationContext(),"Turned on",Toast.LENGTH_LONG).show();
}
if(resultCode == RESULT_CANCELED){

}

Answer 3

您可以使用startActivityForResult()并在您的清单文件中检查onActivityResult()中的 resultCode 是否为 RESULT_OK 并具有蓝牙权限。

mBluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
if (!mBluetoothAdapter.isEnabled()) {
    Intent enableIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
    startActivityForResult(enableIntent, 0);
}

onActivityResult

@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
    super.onActivityResult(requestCode, resultCode, data);
    if(resultCode == RESULT_OK){
        // bluetooth enabled                      
    }else{
        // show error
    }       
}

ACTION_REQUEST_ENABLE

Answer 4

startActivityForResult（enableBtIntent，REQUEST_ENABLE_BT）;

@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
    super.onActivityResult(requestCode, resultCode, data);
    //do your things
}

如何等到蓝牙在android中打开

4 个答案: