程式碼：

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="啟動鬧鐘"
        android:id="@+id/button"
        android:onClick="startAlarmClick"
        android:layout_alignParentEnd="true"
        android:layout_alignParentStart="true" />

    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="設定鬧鐘"
        android:id="@+id/button2"
        android:layout_below="@+id/button"
        android:onClick="startSetAlarmClick"
        android:layout_alignParentStart="true"
        android:layout_alignParentEnd="true" />

</RelativeLayout>
 

package com.example.haige.alarmmanager;

import android.app.Activity;
import android.app.AlarmManager;
import android.app.PendingIntent;
import android.content.Context;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
public class MainActivity extends Activity
{
    protected void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
    }

    /*
    啟動鬧鐘
     */
    public void startAlarmClick(View view)
    {
        //獲取系統的鬧鐘服務
        AlarmManager am= (AlarmManager) getSystemService(Context.ALARM_SERVICE);
        //觸發鬧鐘的時間（毫秒）
        long triggerTime= System.currentTimeMillis()+3000;
        Intent intent=new Intent(this,Alarmctivity.class);
        PendingIntent op=PendingIntent.getActivity(this,0,intent,PendingIntent.FLAG_UPDATE_CURRENT);
        //啟動一次只會執行一次的鬧鐘
        am.set(AlarmManager.RTC,triggerTime,op);
//        //指定時間重複執行鬧鐘
//        am.setRepeating(AlarmManager.RTC,triggerTime,2000,op);
    }

    /*
    設定鬧鐘
     */
    public void startSetAlarmClick(View view)
    {
        //獲取系統的鬧鐘服務
        AlarmManager am= (AlarmManager) getSystemService(Context.ALARM_SERVICE);
        //觸發鬧鐘的時間（毫秒）
        long triggerTime= System.currentTimeMillis()+3000;
        Intent intent=new Intent(this,AlarmReceiver.class);
        PendingIntent op=PendingIntent.getBroadcast(this,0,intent,PendingIntent.FLAG_UPDATE_CURRENT);
        //啟動一次只會執行一次的鬧鐘
        am.set(AlarmManager.RTC,triggerTime,op);
//        //指定時間重複執行鬧鐘
//        am.setRepeating(AlarmManager.RTC,triggerTime,2000,op);
    }
}
 

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context="com.example.haige.alarmmanager.Alarmctivity">

</RelativeLayout>
 

package com.example.haige.alarmmanager;

import android.app.Activity;
import android.app.AlarmManager;
import android.app.AlertDialog;
import android.app.PendingIntent;
import android.content.Context;
import android.content.DialogInterface;
import android.content.Intent;
import android.media.MediaPlayer;
import android.net.Uri;
import android.os.Bundle;
import java.io.IOException;

public class Alarmctivity extends Activity
{
    MediaPlayer mp;
    protected void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_alarmctivity);
        mp = new MediaPlayer();
        try {
            mp.setDataSource(this, Uri.parse("/storage/sdcard1/kugou/聽力/南拳媽媽-你不像她.mp3"));
            mp.prepare();
        } catch (IOException e) {
            e.printStackTrace();
        }
        mp.setLooping(true);
        mp.start();
        alarmOialog();
    }


    @Override
    protected void onResume() {
        super.onResume();
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        if(mp!=null)
        {
           if(mp.isPlaying())
           {
               mp.stop();
           }
            mp.release();
        }
    }

    public void alarmOialog() {
        AlertDialog.Builder builder = new AlertDialog.Builder(this);
        builder.setMessage("大哥，大妹子喊你起床啦！");
        builder.setPositiveButton("再來一次", new DialogInterface.OnClickListener() {

            @Override
            public void onClick(DialogInterface dialogInterface, int i) {
                alarm();
                finish();
            }
        });

        builder.setNegativeButton("停止", new DialogInterface.OnClickListener() {

            @Override
            public void onClick(DialogInterface dialogInterface, int i) {
                finish();//關閉視窗
            }
        });
        builder.show();
    }

    private void alarm() {
        //獲取系統的鬧鐘服務
        AlarmManager am = (AlarmManager) getSystemService(Context.ALARM_SERVICE);
        //觸發鬧鐘的時間（毫秒）
        long triggerTime = System.currentTimeMillis() + 5000;
        Intent intent = new Intent(this, Alarmctivity.class);
        PendingIntent op = PendingIntent.getActivity(this, 0, intent, PendingIntent.FLAG_UPDATE_CURRENT);
        //啟動一次只會執行一次的鬧鐘
        am.set(AlarmManager.RTC, triggerTime, op);
        //指定時間重複執行鬧鐘
//        am.setRepeating(AlarmManager.RTC,triggerTime,2000,op);
    }

}

package com.example.haige.alarmmanager;

import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.widget.Toast;

public class AlarmReceiver extends BroadcastReceiver {
    public AlarmReceiver() {
    }

    @Override
    public void onReceive(Context context, Intent intent) {
        Toast.makeText(context,"起床啦，起床啦！",Toast.LENGTH_SHORT).show();
    }
}