一、開發(fā)手機鬧鐘主要用到了AlarmManager類，AlarmManager類提供了訪問系統(tǒng)定時服務的途徑，開發(fā)人員可以在程序中設置某個應用程序在未來的某個時刻被執(zhí)行。當AlarmManager定時時間到了之后，當初注冊的Intent對象將會被系統(tǒng)廣播，進而啟動目標程序。

二、在程序運行時當需要使用AlarmManager類時，可以通過Context對象的getSystemService(Context.ALARM_SERVICE)方法來獲得AlarmManager對象。

以下程序中使用時間選擇對話框設置鬧鐘的時間。

main.xml布局文件：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
 android:orientation="vertical" 
 android:layout_width="fill_parent"
 android:layout_height="fill_parent">
 <Button android:id="@+id/btn" 
  android:text="設置鬧鐘"
  android:layout_width="fill_parent"
  android:layout_height="wrap_content" />
</LinearLayout>

清單文件：

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
 package="com.ljq.activity" android:versionCode="1"
 android:versionName="1.0">
 <application android:icon="@drawable/icon"
  android:label="@string/app_name">
  <activity android:name=".MainActivity"
   android:label="@string/app_name">
   <intent-filter>
    <action android:name="android.intent.action.MAIN" />
    <category
     android:name="android.intent.category.LAUNCHER" />
   </intent-filter>
  </activity>
  <activity android:name=".AlarmActivity" />
  <!-- android:process=":remote": 新開一個進程 -->
  <receiver android:name=".AlarmReceiver" android:process=":remote"/>
 </application>
 <uses-sdk android:minSdkVersion="7" />
</manifest>

AlarmReceiver類：

package com.ljq.activity;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
public class AlarmReceiver extends BroadcastReceiver{
 @Override
 public void onReceive(Context context, Intent intent) {
  Intent i=new Intent(context, AlarmActivity.class);
  i.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
  context.startActivity(i);
 }
}

AlarmActivity類：

package com.ljq.activity;
import android.app.Activity;
import android.app.AlertDialog;
import android.content.DialogInterface;
import android.content.DialogInterface.OnClickListener;
import android.os.Bundle;
public class AlarmActivity extends Activity {
 @Override
 public void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  //顯示對話框
  new AlertDialog.Builder(AlarmActivity.this).
   setTitle("鬧鐘").//設置標題
   setMessage("時間到了！").//設置內(nèi)容
   setPositiveButton("知道了", new OnClickListener(){//設置按鈕
    public void onClick(DialogInterface dialog, int which) {
     AlarmActivity.this.finish();//關(guān)閉Activity
    }
   }).create().show();
 }
}

MainActivity類：

package com.ljq.activity;
import java.util.Calendar;
import android.app.Activity;
import android.app.AlarmManager;
import android.app.Dialog;
import android.app.PendingIntent;
import android.app.TimePickerDialog;
import android.content.Context;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.TimePicker;
import android.widget.Toast;
public class MainActivity extends Activity{
 private Button btn=null;
 private AlarmManager alarmManager=null;
 Calendar cal=Calendar.getInstance();
 final int DIALOG_TIME = 0; //設置對話框id
 @Override
 protected void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.main);
  alarmManager=(AlarmManager)getSystemService(Context.ALARM_SERVICE);
  btn=(Button)findViewById(R.id.btn);
  btn.setOnClickListener(new View.OnClickListener(){
   public void onClick(View view) {
    showDialog(DIALOG_TIME);//顯示時間選擇對話框
   }
  });
 }
 @Override
 protected Dialog onCreateDialog(int id) {
  Dialog dialog=null;
  switch (id) {
  case DIALOG_TIME:
   dialog=new TimePickerDialog(
     this, 
     new TimePickerDialog.OnTimeSetListener(){
      public void onTimeSet(TimePicker timePicker, int hourOfDay,int minute) {
       Calendar c=Calendar.getInstance();//獲取日期對象 
       c.setTimeInMillis(System.currentTimeMillis());  //設置Calendar對象
       c.set(Calendar.HOUR, hourOfDay);  //設置鬧鐘小時數(shù)
       c.set(Calendar.MINUTE, minute);   //設置鬧鐘的分鐘數(shù)
       c.set(Calendar.SECOND, 0);    //設置鬧鐘的秒數(shù)
       c.set(Calendar.MILLISECOND, 0);   //設置鬧鐘的毫秒數(shù)
       Intent intent = new Intent(MainActivity.this, AlarmReceiver.class); //創(chuàng)建Intent對象
       PendingIntent pi = PendingIntent.getBroadcast(MainActivity.this, 0, intent, 0); //創(chuàng)建PendingIntent
       //alarmManager.set(AlarmManager.RTC_WAKEUP, c.getTimeInMillis(), pi);  //設置鬧鐘
       alarmManager.set(AlarmManager.RTC_WAKEUP, System.currentTimeMillis(), pi);  //設置鬧鐘，當前時間就喚醒
       Toast.makeText(MainActivity.this, "鬧鐘設置成功", Toast.LENGTH_LONG).show();//提示用戶
      }
     }, 
     cal.get(Calendar.HOUR_OF_DAY), 
     cal.get(Calendar.MINUTE),
     false);
   break;
  }
  return dialog;
 }
}

運行結(jié)果：