startForeground无法显示我的通知

Question

startForeground()无法显示下面的通知，这是为了保持监测接近传感器变化的服务处于活动状态。日志中没有错误。

这是我开始服务的地方

Intent intent = new Intent(ctx, ProximityService.class);
if(Build.VERSION.SDK_INT >= Build.VERSION_CODES.O){
ctx.startForegroundService(intent);
} else {
ctx.startService(intent);
}

ProximityService类

public class ProximityService extends IntentService implements SensorEventListener {
@RequiresApi(api = Build.VERSION_CODES.O)
private void startMyOwnForeground(){
String NOTIFICATION_CHANNEL_ID = "com.example.xxxxxx";
String channelName = "Background Proximity Service";
NotificationChannel chan = new NotificationChannel(NOTIFICATION_CHANNEL_ID, channelName, NotificationManager.IMPORTANCE_HIGH);
chan.setLightColor(Color.BLUE);
chan.setLockscreenVisibility(Notification.VISIBILITY_PRIVATE);
NotificationManager manager = (NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);
assert manager != null;
manager.createNotificationChannel(chan);
NotificationCompat.Builder notificationBuilder = new NotificationCompat.Builder(this, NOTIFICATION_CHANNEL_ID);
Notification notification = notificationBuilder.setOngoing(true)
.setSmallIcon(R.drawable.ic_launcher_foreground)
.setContentTitle("App is running in background")
.setPriority(NotificationManager.IMPORTANCE_HIGH)
.setCategory(Notification.CATEGORY_SERVICE)
.build();
startForeground(1, notification);
}
@Override
public void onCreate() {
super.onCreate();
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O)
startMyOwnForeground();
else
startForeground(1, new Notification());
}
@Override
public int onStartCommand(Intent aIntent, int aFlags, int aStartId){
super.onStartCommand(aIntent, aFlags, aStartId);
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O)
startMyOwnForeground();
else
startForeground(1, new Notification());

return START_STICKY;
}
@RequiresApi(api = Build.VERSION_CODES.LOLLIPOP)
public void onSensorChanged(SensorEvent event) {
if (event.sensor.getType() == Sensor.TYPE_PROXIMITY) {
if (event.values[0] < event.sensor.getMaximumRange()) {
// near
Toast.makeText(getApplicationContext(), "near", Toast.LENGTH_SHORT).show();
} else {
// far
Toast.makeText(getApplicationContext(), "far", Toast.LENGTH_SHORT).show();
}
}
}
public ProximityService() {
super("Proximity Service");
}

protected void onHandleIntent(Intent workIntent) {
SensorManager m_sensor_manager = (SensorManager) getSystemService(SENSOR_SERVICE);
Sensor m_prox = m_sensor_manager.getDefaultSensor(Sensor.TYPE_PROXIMITY);
m_sensor_manager.registerListener(this, m_prox, SensorManager.SENSOR_DELAY_NORMAL);
}

AndroidManifest.xml

<uses-permission android:name="android.permission.FOREGROUND_SERVICE" />
<service android:enabled="true" android:name=".ProximityService"/>

build.gradle

android {
compileSdkVersion 29
buildToolsVersion "29.0.3"
defaultConfig {
applicationId "com.example.xxxxxx"
minSdkVersion 16
targetSdkVersion 29
versionCode 1
versionName "1.0"

Answer 1

问题是自定义前台服务是从IntentService而不是Service类扩展的；当onHandleIntent()完成时，IntentService将自动停止，因此不会出现通知。请查看此处以获得完整的理解。

因此，您需要从Service类进行扩展，并相应地重写onBind()。所以，把它附加到你的类中：

@Nullable
@Override
public IBinder onBind(Intent intent) {
return null;
}

还要注意，IntentService在API 30级时已弃用，并由WorkManager或JobIntentService替代