android - 在后台运行 BLE ScanCallback
问题描述
我希望能够在后台扫描 BLE 标签。
我已阅读有关使用服务来执行此操作的信息。但是,当服务被执行,然后我在手机上运行另一个应用程序时,BLE 扫描回调停止执行,但服务仍然正常运行。
我知道 BLE 回调停止是因为 log cat 停止生成日志数据,直到我再次打开应用程序。
以下是我的 MainActivity:
public class MainActivity extends AppCompatActivity {
BluetoothManager btManager;
BluetoothAdapter btAdapter;
BluetoothLeScanner btScanner;
Button startScanningButton;
Button stopScanningButton;
TextView peripheralTextView;
private NotificationManagerCompat notificationManager;
private final static int REQUEST_ENABLE_BT = 1;
private static final int PERMISSION_REQUEST_COARSE_LOCATION = 1;
private static final String TAG = "ExampleJobService";
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Log.d(TAG, "onCreate MAIN");
notificationManager = NotificationManagerCompat.from(this);
peripheralTextView = (TextView) findViewById(R.id.PeripheralTextView);
peripheralTextView.setMovementMethod(new ScrollingMovementMethod());
startScanningButton = (Button) findViewById(R.id.StartScanButton);
startScanningButton.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
Log.d(TAG, "Start button");
startService(new Intent(MainActivity.this, ExampleService.class));
}
});
stopScanningButton = (Button) findViewById(R.id.StopScanButton);
stopScanningButton.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
Log.d(TAG, "Stop 1");
Intent serviceIntent = new Intent(MainActivity.this, ExampleService.class);
stopScanning();
stopService(serviceIntent);
Log.d(TAG, "Stop 2");
}
});
btManager = (BluetoothManager)getSystemService(Context.BLUETOOTH_SERVICE);
btAdapter = btManager.getAdapter();
btScanner = btAdapter.getBluetoothLeScanner();
if (btAdapter != null && !btAdapter.isEnabled()) {
Intent enableIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
startActivityForResult(enableIntent,REQUEST_ENABLE_BT);
}
// Make sure we have access coarse location enabled, if not, prompt the user to enable it
if (this.checkSelfPermission(Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
final AlertDialog.Builder builder = new AlertDialog.Builder(this);
builder.setTitle("This app needs location access");
builder.setMessage("Please grant location access so this app can detect peripherals.");
builder.setPositiveButton(android.R.string.ok, null);
builder.setOnDismissListener(new DialogInterface.OnDismissListener() {
@Override
public void onDismiss(DialogInterface dialog) {
requestPermissions(new String[]{Manifest.permission.ACCESS_COARSE_LOCATION}, PERMISSION_REQUEST_COARSE_LOCATION);
}
});
builder.show();
}
}
@Override
public void onRequestPermissionsResult(int requestCode, String permissions[], int[] grantResults) {
switch (requestCode) {
case PERMISSION_REQUEST_COARSE_LOCATION: {
if (grantResults[0] == PackageManager.PERMISSION_GRANTED) {
System.out.println("coarse location permission granted");
} else {
final AlertDialog.Builder builder = new AlertDialog.Builder(this);
builder.setTitle("Functionality limited");
builder.setMessage("Since location access has not been granted, this app will not be able to discover beacons when in the background.");
builder.setPositiveButton(android.R.string.ok, null);
builder.setOnDismissListener(new DialogInterface.OnDismissListener() {
@Override
public void onDismiss(DialogInterface dialog) {
}
});
builder.show();
}
return;
}
}
}
public void startScanning() {
peripheralTextView.setText("");
AsyncTask.execute(new Runnable() {
@Override
public void run() {
btScanner.startScan(leScanCallback);
}
});
}
public void stopScanning() {
System.out.println("stopping scanning");
peripheralTextView.append("Stopped Scanning");
AsyncTask.execute(new Runnable() {
@Override
public void run() {
btScanner.stopScan(leScanCallback);
}
});
}
}
下面是示例服务:
public class ExampleService extends Service {
BluetoothManager btManager;
BluetoothAdapter btAdapter;
BluetoothLeScanner btScanner;
TextView peripheralTextView;
private NotificationManagerCompat notificationManager;
private static final String TAG = "ExampleJobService";
@Override
public void onCreate() {
super.onCreate();
Log.d(TAG, "onCreate");
}
@Override
public int onStartCommand(Intent intent, int flags, int startId) {
Log.d(TAG, "onStartCommand");
btManager = (BluetoothManager)getSystemService(Context.BLUETOOTH_SERVICE);
btAdapter = btManager.getAdapter();
btScanner = btAdapter.getBluetoothLeScanner();
//do heavy work on a background thread
AsyncTask.execute(new Runnable() {
@Override
public void run() {
btScanner.startScan(leScanCallback);
}
});
return START_REDELIVER_INTENT;
}
private ScanCallback leScanCallback = new ScanCallback() {
@RequiresApi(api = Build.VERSION_CODES.O)
@Override
public void onScanResult(int callbackType, ScanResult result) {
Log.d(TAG, "BLE executed");
if(result.getDevice().getAddress().equals("EE:7E:DE:9B:65:46") && result.getRssi() > -80){
Log.d(TAG, "Tag found");
}
}
};
@Override
public void onDestroy() {
Log.d(TAG, "Destroy");
super.onDestroy();
}
@Nullable
@Override
public IBinder onBind(Intent intent) {
return null;
}
}
编辑1:
String[] peripheralAddresses = new String[]{"EE:7E:DE:9B:65:46"};
@Override
public int onStartCommand(Intent intent, int flags, int startId) {
Log.d(TAG, "onStartCommand");
Intent notificationIntent = new Intent(this, MainActivity.class);
PendingIntent pendingIntent = PendingIntent.getActivity(this,
0, notificationIntent, 0);
Notification notification = new NotificationCompat.Builder(this, CHANNEL_ID)
.setContentTitle("Example Service")
.setContentText("input")
.setSmallIcon(R.drawable.ic_one)
.setContentIntent(pendingIntent)
.build();
startForeground(1, notification);
ScanSettings settings = new ScanSettings.Builder()
.setScanMode(ScanSettings.SCAN_MODE_LOW_POWER)
.build();
// Build filters list
List<ScanFilter> filters = null;
if (peripheralAddresses != null) {
filters = new ArrayList<>();
for (String address : peripheralAddresses) {
ScanFilter filter = new ScanFilter.Builder()
.setDeviceAddress(address)
.build();
filters.add(filter);
}
}
btScanner.startScan(filters, settings, leScanCallback);
return START_STICKY;
}
解决方案
首先,我建议您添加扫描过滤器,因为如果您没有扫描过滤器,Android 会在一段时间后停止扫描。
其次,您的服务不会长期存在,因为如果您设备的 Android 版本或多或等于 Android Oreo(Android 8),Android 会杀死它。
因此,我建议您阅读本文以找到更好的解决方案。
希望对你有帮助!
推荐阅读
- vba - VBA 与外部源通信
- javascript - 如何使页面无法检测到我正在使用 puppeteer 中的自动化控件
- java - 将 add() 方法重写为另一个 Java 类中的私有 Set<>?
- python - 在 venv 中导入已安装的模块时出现 ModuleNotFoundError
- android - 居中裁剪图像与背景
- html - 我希望能够针对不同尺寸的屏幕缩小/放大我的网页
- ibm-watson - 数据精炼厂中从字符串到日期的数据格式转换错误,Watson Studio
- javascript - Internet Explorer 中 => 符号的语法错误
- c# - 找出导航栏中显示的文本的默认字体大小
- ubuntu - 为什么我的 python 脚本在 linux 上静默停止?