https://blog.csdn.net/guolin_blog/article/details/79854070

运行之前先把手机里的通知权限(应用管理里面)打开,暂时先总结这么多

 text.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Toast.makeText(NormalActivity.this, "dianji", Toast.LENGTH_SHORT).show();
                if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
                    String channelId = "chat";
                    String channelName = "聊天消息";
                    int importance = NotificationManager.IMPORTANCE_HIGH;
                    createNotificationChannel(channelId, channelName, importance);

                    channelId = "subscribe";
                    channelName = "订阅消息";
                    importance = NotificationManager.IMPORTANCE_DEFAULT;
                    createNotificationChannel(channelId, channelName, importance);
                }
               sendChatMsg();
                sendSubscribeMsg();
            }
        });

@TargetApi(Build.VERSION_CODES.O)
    private void createNotificationChannel(String channelId, String channelName, int importance) {
        NotificationChannel channel = new NotificationChannel(channelId, channelName, importance);
        NotificationManager notificationManager = (NotificationManager) getSystemService(
                NOTIFICATION_SERVICE);
        notificationManager.createNotificationChannel(channel);
    }

    public void sendChatMsg() {
        NotificationManager manager = (NotificationManager) getSystemService(NOTIFICATION_SERVICE);
        Notification notification = new NotificationCompat.Builder(this, "chat")
                .setContentTitle("收到一条聊天消息")
                .setContentText("今天中午吃什么？")
                .setSmallIcon(R.drawable.ic_launcher_background)
                .setWhen(System.currentTimeMillis())
                .setLargeIcon(BitmapFactory.decodeResource(getResources(), R.drawable.ic_launcher_background))
                .setAutoCancel(true)
                .build();
        manager.notify(1, notification);
    }

    public void sendSubscribeMsg() {
        NotificationManager manager = (NotificationManager) getSystemService(NOTIFICATION_SERVICE);
        Notification notification = new NotificationCompat.Builder(this, "subscribe")
                .setContentTitle("收到一条订阅消息")
                .setContentText("地铁沿线30万商铺抢购中！")
                .setWhen(System.currentTimeMillis())
                .setSmallIcon(R.drawable.ic_launcher_background)
                .setLargeIcon(BitmapFactory.decodeResource(getResources(), R.drawable.ic_launcher_background))
                .setAutoCancel(true)
                .build();
        manager.notify(2, notification);
    }