AlarmManager 闹钟服务

 一.闹钟服务流程

1.0.AlarmManager alarmManager = (AlarmManager) getSystemService(ALARM_SERVICE); 获得系统提供的AlarmManager服务的对象
1.1.Intent设置要启动的组件: Intent intent = new Intent(MainActivity.this, SecondActivity.class);
1.3.PendingIntent对象设置动作,启动的是Activity还是Service,又或者是广播!

PendingIntent pi = PendingIntent.getActivity(MainActivity.this, 0, intent, 0);
注意:
     a.获取的是getActivity、getService、getBroadcast
     b.假如你用的是alarmManager发送广播,广播再激活Activity的话，
       则需要为Intent设置一个flag: intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);

1.4.调用AlarmManager的set( )方法设置单次闹钟的闹钟类型,启动时间以及PendingIntent对象

alarmManager.set(AlarmManager.RTC_WAKEUP,c.getTimeInMillis(), pi);
注意:
     a.set(int type,long startTime,PendingIntent pi)：一次性闹钟
     b.setExact(int type, long triggerAtMillis, PendingIntent operation): 在规定的时间精确的执行闹钟，比set方法设置的精度更高
     c.setRepeating(int type，long startTime，long intervalTime，PendingIntent pi): 重复性闹钟,和3有区别,3闹钟间隔时间不固定
     d.cancel(PendingIntent pi): 取消AlarmManager的定时服务

 二.举个栗子……

2.0. 实例每天23:59:00 闹钟

import java.util.Calendar;

import android.app.Activity;
import android.app.AlarmManager;
import android.app.PendingIntent;
import android.content.Intent;
import android.os.Bundle;
import android.util.Log;

public class MainActivity extends Activity {

	AlarmManager alarmManager;

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

		alarmManager = (AlarmManager) getSystemService(ALARM_SERVICE);
		Calendar calendar = Calendar.getInstance();
		calendar.set(Calendar.HOUR_OF_DAY, 23);
		calendar.set(Calendar.MINUTE, 59);
		calendar.set(Calendar.SECOND, 0);
		calendar.set(Calendar.MILLISECOND, 0);

		Intent intent = new Intent();
		intent.setClassName("com.gatsby.networktime", "com.gatsby.networktime.SecondActivity");
		intent.putExtra("msg", "helloWorld");

		// 当前系统 时间戳
		long systemTime = System.currentTimeMillis();
		Log.d("gatsby", "systemTime->" + System.currentTimeMillis());
		// 闹钟 时间戳
		long alarmTime = calendar.getTimeInMillis();
		Log.d("gatsby", "alarmTime->" + calendar.getTimeInMillis());

		if (systemTime > alarmTime) {
			// 如果设置的时间小于当前时间,闹钟时间 将添加一天,即明天
			calendar.add(Calendar.DAY_OF_YEAR, 1);
			alarmTime = calendar.getTimeInMillis();
			Log.d("gatsby", "alarmTime2->" + calendar.getTimeInMillis());
		}

		PendingIntent pi = PendingIntent.getActivity(MainActivity.this, 0, intent, 0);
		// 重复每天提醒
		alarmManager.setRepeating(AlarmManager.RTC_WAKEUP, alarmTime, AlarmManager.INTERVAL_DAY, pi);
		Log.d("gatsby", "alarmTime.setRepeating->" + calendar.getTimeInMillis());

	}

}

2.1.取消闹钟

alarmManager.cancel(pi);