运行在模拟器上没有问题，运行在真机上就会报错，是安卓版本问题，使用Notificatio通知再Android8.0以上的的通知要设置渠道，否则就无法显示。

所以在MyService中onCreatet如下代码：

@Override
    public void onCreate() {
        super.onCreate();
        String ID = "com.sidebar.project";	//这里的id里面输入自己的项目的包的路径
        String NAME = "LEFTBAR";
        Intent intent = new Intent(MyService.this, MainActivity.class);
        PendingIntent pendingIntent = PendingIntent.getActivity(this, 0, intent, 0);
        NotificationCompat.Builder notification; //创建服务对象
        NotificationManager manager = (NotificationManager) getSystemService(NOTIFICATION_SERVICE);
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
            NotificationChannel channel = new NotificationChannel(ID, NAME, manager.IMPORTANCE_HIGH);
            channel.enableLights(true);
            channel.setShowBadge(true);
            channel.setLockscreenVisibility(Notification.VISIBILITY_PUBLIC);
            manager.createNotificationChannel(channel);
            notification = new NotificationCompat.Builder(MyService.this).setChannelId(ID);
        } else {
            notification = new NotificationCompat.Builder(MyService.this);
        }
        notification.setContentTitle("标题")
                .setContentText("内容")
                .setWhen(System.currentTimeMillis())
                .setSmallIcon(R.mipmap.ic_launcher)
                .setLargeIcon(BitmapFactory.decodeResource(getResources(), R.mipmap.ic_launcher))
                .setContentIntent(pendingIntent)
                .build();
        Notification notification1 = notification.build();
        startForeground(1,notification1);
        //manager.notify(1,notification1);
    }