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