Android之手机闹钟

一、开发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

<?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="设置闹钟"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content" />
</LinearLayout>

清单文件

<?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": 新开一个进程 -->
        <receiver android:name=".AlarmReceiver" android:process=":remote"/>
    </application>
    <uses-sdk android:minSdkVersion="7" />
</manifest>

AlarmReceiver类

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 {
    
    @Override
    public 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

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;    //设置对话框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);//显示时间选择对话框
            }
        });

    }
    
    @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();//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