对于Kitkat 4.4.4,按照update + appCompat的规定,以下代码和权限可能无法正常运行6.01中的Bluetooth。
没有返回任何结果,附近有几个可发现的设备。
任何人都有什么见解,为什么?我在Nexus 5上运行。
<uses-permission android:name="android.permission.BLUETOOTH_ADMIN" />
<uses-permission android:name="android.permission.BLUETOOTH" />
<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
package bluetoothscanneractivity;
import android.app.Activity;
import android.bluetooth.BluetoothAdapter;
import android.bluetooth.BluetoothDevice;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.ListView;
import android.widget.Toast;
import java.util.ArrayList;
public class BluetoothScannerActivity extends Activity {
//private final BroadcastReceiver FoundReceiver = null;
protected ArrayList<BluetoothDevice> foundDevices = new ArrayList<BluetoothDevice>();
private ListView foundDevicesListView;
private ArrayAdapter<BluetoothDevice> btArrayAdapter;
/**
* Called when the activity is first created.
*/
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_bluetooth_scanner);
final BluetoothAdapter myBlueToothAdapter = BluetoothAdapter.getDefaultAdapter();
final Button scanb = (Button) findViewById(R.id.button);
final ListView foundDevicesListView = (ListView) findViewById(R.id.listView1);
btArrayAdapter = new ArrayAdapter<BluetoothDevice>(this,
android.R.layout.simple_list_item_1, foundDevices);
foundDevicesListView.setAdapter(btArrayAdapter);
//Turn on Bluetooth
if (myBlueToothAdapter == null)
Toast.makeText(BluetoothScannerActivity.this, "Your device doesnot support Bluetooth", Toast.LENGTH_LONG).show();
else if (!myBlueToothAdapter.isEnabled()) {
Intent BtIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
startActivityForResult(BtIntent, 0);
Toast.makeText(BluetoothScannerActivity.this, "Turning on Bluetooth", Toast.LENGTH_LONG).show();
}
//scan
scanb.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
btArrayAdapter.clear();
myBlueToothAdapter.startDiscovery();
Toast.makeText(BluetoothScannerActivity.this, "Scanning Devices", Toast.LENGTH_LONG).show();
}
});
registerReceiver(FoundReceiver, new IntentFilter(BluetoothDevice.ACTION_FOUND));
IntentFilter filter = new IntentFilter(
BluetoothAdapter.ACTION_DISCOVERY_FINISHED);
this.registerReceiver(FoundReceiver, filter);
}
@Override
protected void onDestroy() {
// TODO Auto-generated method stub
super.onDestroy();
unregisterReceiver(FoundReceiver);
}
private final BroadcastReceiver FoundReceiver = new BroadcastReceiver() {
@Override
public void onReceive(Context context, Intent intent) {
String action = intent.getAction();
// When discovery finds a new device
if (BluetoothDevice.ACTION_FOUND.equals(action)) {
// Get the BluetoothDevice object from the Intent
BluetoothDevice device = intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);
if (!foundDevices.contains(device)) {
foundDevices.add(device);
btArrayAdapter.notifyDataSetChanged();
}
}
// When discovery cycle finished
if (BluetoothAdapter.ACTION_DISCOVERY_FINISHED.equals(action)) {
if (foundDevices == null || foundDevices.isEmpty()) {
Toast.makeText(BluetoothScannerActivity.this, "No Devices", Toast.LENGTH_LONG).show();
}
}
}
};
}
最佳答案
您知道自Marshmallow
以来,您需要这些权限来执行任务-
<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
同样从
Marshmallow
开始,即使您已在 list 文件中声明了权限,也必须以编程方式请求权限。因此,您必须先申请位置权限,然后再使用
startDiscovery()
ActivityCompat.requestPermissions(this,new String[]{Manifest.permission.ACCESS_FINE_LOCATION, Manifest.permission.ACCESS_COARSE_LOCATION}, 1001); //Any number
在用户接受这些权限之后,您可以
startDiscovery()
。如果他/她否认,您将无法找到设备。您可以在以下位置检查用户操作
onRequestPermissionsResult()
回调。