AlarmManager manager= (AlarmManager) getSystemService(Context.ACTIVITY_SERVICE);
 PendingIntent pendingIntent;
      /**
         *    SystemClock.elapsedRealtime():獲取到系統(tǒng)開機至今所經(jīng)歷的毫秒數(shù)
         *    System.currentTimeMillis():1970-1-1 0:00至今所經(jīng)歷的毫秒數(shù)
         *
         *     ELAPSED_REALTIME:定時任務(wù)觸發(fā)從系統(tǒng)開機算起 但不喚醒CPU
         *     ELAPSED_REALTIME_WAKEUP:定時任務(wù)觸發(fā)從系統(tǒng)開機算起 喚醒CPU
         *     RTC:從1970-1-1 0:00算起 不喚醒CPU
         *     RTC_WAKEUP:從1970-1-1 0:00算起 喚醒CPU
         */
    /**pendIntent：一般會調(diào)用getSrervice或getBroadCast
       來獲取一個能夠執(zhí)行服務(wù)或廣播的pendingIntent，
       這樣才能保證在任務(wù)被觸發(fā)的時候，
       服務(wù)里的onStartCommand()和onRecive()方法被執(zhí)行   
      */
   long time= SystemClock.elapsedRealtime()+10*1000;//10秒鐘后執(zhí)行任務(wù)
   manager.set(AlarmManager.ELAPSED_REALTIME_WAKEUP,time,pendingIntent);

package com.example.test;
import android.app.AlarmManager;
import android.app.PendingIntent;
import android.app.Service;
import android.content.Intent;
import android.os.IBinder;
import android.os.SystemClock;
import androidx.annotation.Nullable;
public class MyService extends Service {
    @Nullable
    @Override
    public IBinder onBind(Intent intent) {
        return null;
    }
    @Override
    public int onStartCommand(Intent intent, int flags, int startId) {
        new Thread(new Runnable() {
            @Override
            public void run() {
                //TODO
            }
        }).start();
        AlarmManager manager= (AlarmManager) getSystemService(ALARM_SERVICE);
        int time=60*60*1000;//一小時
        long triggerAtTime= SystemClock.elapsedRealtime()+time;
        Intent intent1=new Intent(this,MyService.class);
        PendingIntent pendingIntent=PendingIntent.getService(this,0,intent1,0);
        manager.set(AlarmManager.ELAPSED_REALTIME_WAKEUP,triggerAtTime,pendingIntent);
        return super.onStartCommand(intent, flags, startId);
    }
}

<service android:name=".MyService"/>

    Intent intent=new Intent(context,MyService.class);
    context.startService(intent);