<?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"
    tools:context=".DetailActivity">

    <ImageView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:src="@drawable/b"
        />

</LinearLayout>

<?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"
    tools:context=".MainActivity">



</LinearLayout>

package com.example.mynotifyi;

import androidx.appcompat.app.AppCompatActivity;

import android.os.Bundle;

public class DetailActivity extends AppCompatActivity {

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

package com.example.mynotifyi;

import androidx.appcompat.app.AppCompatActivity;

import android.app.Notification;
import android.app.NotificationManager;
import android.app.PendingIntent;
import android.content.Intent;
import android.os.Bundle;

import java.util.prefs.NodeChangeEvent;

public class MainActivity extends AppCompatActivity {

    final private int NOTIFYID = 0x123;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        //创建并发送通知
        //获得系统服务的通知管理器
        NotificationManager notificationManager = (NotificationManager) getSystemService(NOTIFICATION_SERVICE);
        //获得一个通知Builder对象
        Notification.Builder builder = new Notification.Builder(MainActivity.this);
        builder.setAutoCancel(true);//设置通知打开后自动消失
       // builder.setSmallIcon(R.drawable.b);//通知图标
        builder.setContentTitle("通知标题");
        builder.setContentText("通知内容");
        builder.setWhen(System.currentTimeMillis());//设置发送时间
        builder.setDefaults(Notification.DEFAULT_SOUND| Notification.DEFAULT_VIBRATE);//设置默认声音，振动
        //创建一个启动详细页面的Intent对象
        Intent intent = new Intent(
                MainActivity.this,DetailActivity.class
        );
        //创建可以由其他应用程序在稍晚进行出发的Intent机制，即让Detail在点击了消息后再触发
        PendingIntent pi = PendingIntent.getActivity(
                MainActivity.this,0,intent,0
        );
        builder.setContentIntent(pi);//设置通知栏点击跳转
        //通知管理器发送通知
        notificationManager.notify(NOTIFYID,builder.build());

    }
}