Android P 发通知

 NotificationManager manager =
                (NotificationManager) getSystemService(NOTIFICATION_SERVICE);
        Notification notification = null;
        //第二步：实例化通知栏构造器NotificationCompat.Builder：
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {//判断API
            NotificationChannel mChannel = new NotificationChannel(id, name,
                    NotificationManager.IMPORTANCE_HIGH);

            manager.createNotificationChannel(mChannel);

            notification = new NotificationCompat.Builder(this, id)

                    .setContentTitle("这是一个内容标题11")//设置通知栏标题
                    .setContentText("10") //设置通知栏显示内容
                    .setWhen(System.currentTimeMillis())//通知产生的时间。
                    // 会在通知信息里显示，通常是系统获取到的时间
                    .setSmallIcon(R.drawable.b)//设置通知小ICON
                   
                    .build();
        } else {
            NotificationCompat.Builder notificationBuilder =
                    new NotificationCompat.Builder(this, id)
                            .setContentTitle("这是一个内容标题")
                            .setContentText("1")
                            .setSmallIcon(R.drawable.a)
                            .setLargeIcon(BitmapFactory.decodeResource(getResources()
                                    , R.mipmap.ic_launcher));
//                                    .setOngoing(true);
            notification = notificationBuilder.build();

        }
        //第三步：对Builder进行配置：
        manager.notify(1, notification);