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一、手机闹钟主要用到了AlarmManager类，AlarmManager类提供了访问系统定时服务的途径，开发人员可以在程序中设置某个应用程序在未来的某个时刻被执行。当AlarmManager定时时间到了之后，当初注册的Intent对象将会被系统广播，进而启动目标程序。

二、在程序运行时当需要使用AlarmManager类时，可以通过Context对象的getSystemService(Context.ALARM_SERVICE)方法来获得AlarmManager对象。

以下程序中使用时间选择对话框设置闹钟的时间。

main.xml布局文件

 

清单文件

 

AlarmReceiver类

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

 

AlarmActivity类

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 {@Overridepublic void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);//显示对话框new AlertDialog.Builder(AlarmActivity.this).setTitle("闹钟").//设置标题setMessage("时间到了！").//设置内容setPositiveButton("知道了", new OnClickListener(){
         //设置按钮public void onClick(DialogInterface dialog, int which) {AlarmActivity.this.finish();//关闭Activity}}).create().show();}}

 

MainActivity类

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; //设置对话框id@Overrideprotected 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);//显示时间选择对话框}});}@Overrideprotected 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();//获取日期对象 c.setTimeInMillis(System.currentTimeMillis()); //设置Calendar对象c.set(Calendar.HOUR, hourOfDay); //设置闹钟小时数c.set(Calendar.MINUTE, minute); //设置闹钟的分钟数c.set(Calendar.SECOND, 0); //设置闹钟的秒数c.set(Calendar.MILLISECOND, 0); //设置闹钟的毫秒数Intent intent = new Intent(MainActivity.this, AlarmReceiver.class); //创建Intent对象PendingIntent pi = PendingIntent.getBroadcast(MainActivity.this, 0, intent, 0); //创建PendingIntent//alarmManager.set(AlarmManager.RTC_WAKEUP, c.getTimeInMillis(), pi); //设置闹钟alarmManager.set(AlarmManager.RTC_WAKEUP, System.currentTimeMillis(), pi); //设置闹钟，当前时间就唤醒Toast.makeText(MainActivity.this, "闹钟设置成功", Toast.LENGTH_LONG).show();//提示用户}},cal.get(Calendar.HOUR_OF_DAY),cal.get(Calendar.MINUTE),false);break;}return dialog;}}

 

运行结果