Android 8.0以后 notification 不显示的问题

notification 在安卓8.0以后出现了 不显示的问题。修复好的代码如下：

public class NotificationDemoActivity extends Activity {
    Button  bt_send;
    String channelId ="my channel"; //通知id
    String name="渠道名字";
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_notification);
        bt_send = findViewById(R.id.bt_message);
        bt_send.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
            NotificationManagerCompat manager = NotificationManagerCompat.from(NotificationDemoActivity.this);

            //这里判定 如果是 8.0以上,会出现无效的情况。那么单独额外处理一下
            if(Build.VERSION.SDK_INT>=Build.VERSION_CODES.O){
            NotificationChannel notificationChannel=new NotificationChannel(channelId,name,NotificationManager.IMPORTANCE_LOW);
            NotificationManager notificationManager =
                        (NotificationManager) getApplication().getSystemService(Context.NOTIFICATION_SERVICE);
            notificationManager.createNotificationChannel(notificationChannel);
            }

                Notification notification = new NotificationCompat.Builder(NotificationDemoActivity.this,channelId)
                        .setContentTitle("This is content title")
                        .setContentText("This is content text")
                        .setWhen(System.currentTimeMillis())
                        .setSmallIcon(R.mipmap.ic_launcher)
                        .setDefaults(NotificationCompat.DEFAULT_ALL)
                        .setPriority(NotificationCompat.PRIORITY_MAX)
                        .build();
                manager.notify(1, notification);
            }
        });
    }
}

除了常规用法。核心代码新加如下：

如图。我箭头标注的 部分 额外注意一下。就可以了。