在android8之后，使用Notification需要先创建渠道
伪代码如下

NotificationManager notificationManager=(NotificationManager)getSystemService(Context.NOTIFICATION_SERVICE) ;
        Intent intent=new Intent(this,Second.class);
        Context context=this;
        PendingIntent pendingIntent=PendingIntent.getActivity(context, 0, intent, PendingIntent.FLAG_ONE_SHOT);
        CharSequence name;
        Button v1 = (Button) v;


        NotificationChannel notificationChannel=new NotificationChannel("1", "name", 5);

        notificationManager.createNotificationChannel(notificationChannel);
        NotificationCompat.Builder mb=new NotificationCompat.Builder(this,"1");
        mb.setContentTitle("曾鑫磊")
                .setContentText("如果没住在你心里，都是客死他乡")
                .setSmallIcon(R.mipmap.mm)
                .setTicker("收到一条消息").setWhen(System.currentTimeMillis())
                .setContentIntent(pendingIntent);
        notificationManager.notify(1,mb.build());