先看看效果看看是不是你想要的

点击后

话不多所，贴代码

xml文件：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:padding="10dp"
    tools:context=".MainSendMessage">
    <Button
        android:id="@+id/b1"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="发送通知"
        />

</LinearLayout>

activity代码：

package com.example.love5;

import android.app.Notification;
import android.app.NotificationChannel;
import android.app.NotificationManager;
import android.graphics.BitmapFactory;
import android.graphics.Color;
import android.os.Build;
import android.support.annotation.RequiresApi;
import android.support.v4.app.NotificationCompat;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;


public class MainSendMessage extends AppCompatActivity {
    private Button b1;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main_send_message);

        b1 = findViewById(R.id.b1);
        b1.setOnClickListener(new View.OnClickListener() {
            @RequiresApi(api = Build.VERSION_CODES.O)
            @Override
            public void onClick(View v) {
                NotificationManager manager = (NotificationManager) getSystemService(NOTIFICATION_SERVICE);
                //创建通知渠道实例
                //并为它设置属性
                //通知渠道的ID,随便写
                String id = "channel_01";
                //用户可以看到的通知渠道的名字，R.string.app_name就是strings.xml文件的参数，自定义一个就好了
                CharSequence name = getString(R.string.app_name);
                //用户可看到的通知描述
                String description = getString(R.string.app_name);
                //构建NotificationChannel实例
                NotificationChannel notificationChannel =
                        new NotificationChannel(id, name, NotificationManager.IMPORTANCE_HIGH);
                //配置通知渠道的属性
                notificationChannel.setDescription(description);
                //设置通知出现时的闪光灯
                notificationChannel.enableLights(true);
                notificationChannel.setLightColor(Color.RED);
                //设置通知出现时的震动
                notificationChannel.enableVibration(true);
                notificationChannel.setVibrationPattern(new long[]{100, 200, 300, 400, 500, 400, 300, 200, 100});
                //在notificationManager中创建通知渠道
                manager.createNotificationChannel(notificationChannel);

　　　　　　　　　　//蓝色字是个新方法，旧的被api放弃了
                Notification notification = new NotificationCompat.Builder(MainSendMessage.this, id)
                        .setContentTitle("标题")
                        .setContentText("内容666666666666666666666666666")
                        .setWhen(System.currentTimeMillis())
                        .setSmallIcon(R.drawable.tubiao)
                        .setLargeIcon(BitmapFactory.decodeResource(getResources(), R.drawable.coffee))
                        .build();
                manager.notify(1, notification);


            }
        });


    }
}