适配安卓8.0以上推送通知栏
1.推送弹出通知栏
NotificationManager manager = (NotificationManager) context.getSystemService(Context.NOTIFICATION_SERVICE);
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
// 创建
NotificationChannel channel = new NotificationChannel(id, content, NotificationManager.IMPORTANCE_DEFAULT);
channel.enableLights(true);
channel.enableVibration(true);
channel.setLightColor(Color.BLUE);
channel.setShowBadge(true);
manager.createNotificationChannel(channel);
}

    //自定义打开的界面
    Intent resultIntent = new Intent(context.getApplicationContext(), MainActivity.class);
    resultIntent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP | Intent.FLAG_ACTIVITY_NEW_TASK);
    PendingIntent contentIntent = PendingIntent.getActivity(context.getApplicationContext(), 0, resultIntent, PendingIntent.FLAG_UPDATE_CURRENT);

    NotificationCompat.Builder mBuilder = new NotificationCompat.Builder(context);
    mBuilder.setContentTitle(title)
            .setContentText(content)
            .setContentIntent(contentIntent)
            .setLargeIcon(BitmapFactory.decodeResource(context.getResources(), R.mipmap.ic_logo))
            .setOnlyAlertOnce(true)
            .setAutoCancel(true)
            .setDefaults(Notification.DEFAULT_ALL)
            .setWhen(System.currentTimeMillis())
            .setSmallIcon(R.mipmap.ic_logo)
            .setColor(Color.BLUE);
    manager.notify(1, mBuilder.build());

2.在Service中弹出通知栏
ndroid系统8.0及以上，开启Service必须使用startForegroundService(Intent intent)方法，对应的Service则必须设置startForeground(int id, Notification notification)，因而我们必须创建一个通知，这样在服务运行当中，会一直显示一条“xx正在运行”类似的通知。

在8.0以上系统中开启startService之后5秒内必须开启startForeground(1, notification);

 if (android.os.Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
        Notification notification = new Notification.Builder(getApplicationContext(),createNotificationChannel()).build();
        startForeground(1, notification);
    }

替代方案：
@RequiresApi(api = Build.VERSION_CODES.LOLLIPOP)
public class CowboyJobService extends JobService {

@Override
public boolean onStartJob(JobParameters jobParameters) {

    //此处进行自定义的任务
    return false;
}

@Override
public boolean onStopJob(JobParameters jobParameters) {
    return false;
}

}

//开启JobService服务：CowboyJobService.class为上边创建的JobService
public static void startPollingService(Context context) {

    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
        JobInfo.Builder builder = new JobInfo.Builder(1, new ComponentName(context, CowboyJobService.class));
        builder.setMinimumLatency(0)
                .setBackoffCriteria(JobInfo.DEFAULT_INITIAL_BACKOFF_MILLIS, JobInfo.BACKOFF_POLICY_LINEAR);
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.N) {
            builder.setPeriodic(JobInfo.getMinPeriodMillis(), JobInfo.getMinFlexMillis());
        } else {
            builder.setPeriodic(TimeUnit.MINUTES.toMillis(5));
        }

        JobScheduler jobScheduler = (JobScheduler) context.getSystemService(Context.JOB_SCHEDULER_SERVICE);
        if (jobScheduler != null) {
            jobScheduler.schedule(builder.build());
        }
    } else {
        //系统5.0以下的可继续使用Service
    }
}