AlarmManager提供了一种系统级的提示服务，允许你安排在将来的某个时间执行一个服务。AlarmManager对象一般通过Context.getSystemService(Context.ALARM_SERVICE)方法获得。

下面看一个例子加深理解：

package com.app;

import com.app.R;

import android.app.Activity;
import android.app.AlarmManager;
import android.app.PendingIntent;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;

/**
 * 
 * 测试AlarmManager
 */
public class MainActivity extends Activity {
	// 声明Button
	private Button setBtn, cancelBtn;
	// 定义广播Action
	private static final String BC_ACTION = "com.action.BC_ACTION";

	@Override
	public void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		// 设置当前布局视图
		setContentView(R.layout.main);
		
		// 实例化Button
		setBtn = (Button) findViewById(R.id.Button01);
		cancelBtn = (Button) findViewById(R.id.Button02);
		
		// 获得AlarmManager实例
		final AlarmManager am = (AlarmManager) getSystemService(ALARM_SERVICE);
		
		// 实例化Intent
		Intent intent = new Intent();
		// 设置Intent action属性
		intent.setAction(BC_ACTION);
		intent.putExtra("msg", "你该去开会啦！");
		// 实例化PendingIntent
		final PendingIntent pi = PendingIntent.getBroadcast(MainActivity.this, 0,
				intent, 0);
		// 获得系统时间
		final long time = System.currentTimeMillis();

		// 设置按钮单击事件
		setBtn.setOnClickListener(new OnClickListener() {
			@Override
			public void onClick(View v) {
				// 重复提示，从当前时间开始，间隔5秒
				am.setRepeating(AlarmManager.RTC_WAKEUP, time,
						5 * 1000, pi);
			}
		});
		
		// 设置按钮单击事件
		cancelBtn.setOnClickListener(new OnClickListener() {
			@Override
			public void onClick(View v) {
				am.cancel(pi);
			}
		});
	}
}

注：PendingIntent的一个静态方法，

getBroadcast

public static PendingIntent getBroadcast(Context context,
                                         int requestCode,
                                         Intent intent,
                                         int flags)

Retrieve a PendingIntent that will perform a broadcast, like calling Context.sendBroadcast().

参数：

context - The Context in which this PendingIntent should perform the broadcast.

requestCode - Private request code for the sender (currently not used).

intent - The Intent to be broadcast.

flags - May be FLAG_ONE_SHOT, FLAG_NO_CREATE,FLAG_CANCEL_CURRENT, FLAG_UPDATE_CURRENT, or any of the flags as supported byIntent.fillIn() to control which unspecified parts of the intent that can be supplied when the actual send happens.

返回：

Returns an existing or new PendingIntent matching the given parameters. May return null only ifFLAG_NO_CREATE has been supplied.

package com.app;

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

public class MyReceiver extends BroadcastReceiver {
	@Override
	public void onReceive(Context context, Intent intent) {
		// 获得提示信息
		String msg = intent.getStringExtra("msg");
		// 显示提示信息
		Toast.makeText(context, msg, Toast.LENGTH_LONG).show();
	}
}

<receiver android:name="MyReceiver">
        <intent-filter>
        	<action android:name="com.action.BC_ACTION"/>
        </intent-filter>
 </receiver>

Android闹钟-AlarmManager