为了防止后台服务被系统干掉，我们需要将服务提升为前台服务。
示例代码：
需要在AndroidManifest 添加 前台服务的权限 :
<uses-permission android:name="android.permission.FOREGROUND_SERVICE"/>
FOREGROUND_SERVICE
Added in API level 28 Android 9.0
public static final String FOREGROUND_SERVICE
Allows a regular application to use Service.startForeground.
Protection level: normal
Constant Value: android.permission.FOREGROUND_SERVICE
public class SampleService extends Service { public static final String CHANNEL_ID = "com.github.103style.SampleService"; public static final String CHANNEL_NAME = "com.github.103style"; @Override public IBinder onBind(Intent intent) { return null; } @Override public void onCreate() { super.onCreate(); registerNotificationChannel(); int notifyId = (int) System.currentTimeMillis(); NotificationCompat.Builder mBuilder = new NotificationCompat.Builder(this, CHANNEL_ID); mBuilder //必须要有 .setSmallIcon(R.mipmap.ic_launcher) //可选 //.setSound(null) //.setVibrate(null) //... ; if (Build.VERSION.SDK_INT < Build.VERSION_CODES.N) { mBuilder.setContentTitle(getResources().getString(R.string.app_name)); } startForeground(notifyId, mBuilder.build()); } /** * 注册通知通道 */ private void registerNotificationChannel() { if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) { NotificationManager mNotificationManager = (NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE); NotificationChannel notificationChannel = mNotificationManager.getNotificationChannel(CHANNEL_ID); if (notificationChannel == null) { NotificationChannel channel = new NotificationChannel(CHANNEL_ID, CHANNEL_NAME, NotificationManager.IMPORTANCE_HIGH); //是否在桌面icon右上角展示小红点 channel.enableLights(true); //小红点颜色 channel.setLightColor(Color.RED); //通知显示 channel.setLockscreenVisibility(Notification.VISIBILITY_PUBLIC); //是否在久按桌面图标时显示此渠道的通知 //channel.setShowBadge(true); mNotificationManager.createNotificationChannel(channel); } } }}以上