全局定时器AlarmManager（3）
8.3.5 全局定时器AlarmManager（3）

本例使用BroadcastReceiver来处理定时提醒任务。BroadcastReceiver类的代码如下：
package net.blogjava.mobile;

import java.util.Calendar;
import android.app.Activity;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.SharedPreferences;
import android.media.MediaPlayer;

public class AlarmReceiver extends BroadcastReceiver
{
@Override
public void onReceive(Context context, Intent intent)
{
SharedPreferences sharedPreferences =
context.getSharedPreferences(
"alarm_record", Activity.MODE_PRIVATE);
String hour = String.valueOf(Calendar.
getInstance().get(Calendar.HOUR_OF_DAY));
String minute = String.valueOf(Calendar.
getInstance().get(Calendar.MINUTE));
// 从XML文件中获得描述当前时间点的value
String time = sharedPreferences.
getString(hour + ":" + minute, null);
if (time != null)
{
// 播放声音
MediaPlayer mediaPlayer =
MediaPlayer.create(context, R.raw.ring);
mediaPlayer.start();
}
}
}

配置AlarmReceiver类的代码如下：
<receiver android:name=".AlarmReceiver" android:enabled="true" />

在主程序中每添加一个时间点，就会在XML文件中保存所添加的时间点，代码如下：
package net.blogjava.mobile;

import android.app.Activity;
import android.app.AlarmManager;
import android.app.AlertDialog;
import android.app.PendingIntent;
import android.content.Context;
import android.content.DialogInterface;
import android.content.Intent;
import android.content.SharedPreferences;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.TextView;
import android.widget.TimePicker;

public class Main extends Activity implements OnClickListener
{
private TextView tvAlarmRecord;
private SharedPreferences sharedPreferences;
@Override
public void onClick(View v)
{
View view = getLayoutInflater().inflate(R.layout.alarm, null);
final TimePicker timePicker = (TimePicker)
view.findViewById(R.id.timepicker);
timePicker.setIs24HourView(true);
// 显示设置时间点的对话框
new AlertDialog.Builder(this).setTitle("设置提醒时间").setView(view)
.setPositiveButton("确定", new
DialogInterface.OnClickListener()
{
@Override
public void onClick(DialogInterface dialog, int which)
{
String timeStr = String.valueOf(timePicker
.getCurrentHour()) + ":"
+ String.valueOf
(timePicker.getCurrentMinute());
// 将时间点添加到TextView组件中
tvAlarmRecord.setText
(tvAlarmRecord.getText().toString() + "\n" + timeStr);
// 保存时间点
sharedPreferences.edit().
putString(timeStr, timeStr).commit();
}
}).setNegativeButton("取消", null).show();
}
@Override
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
Button btnAddAlarm = (Button) findViewById(R.id.btnAddAlarm);
tvAlarmRecord = (TextView) findViewById(R.id.tvAlarmRecord);
btnAddAlarm.setOnClickListener(this);
sharedPreferences = getSharedPreferences("alarm_record",
Activity.MODE_PRIVATE);
AlarmManager alarmManager = (AlarmManager)
getSystemService(Context.ALARM_SERVICE);
Intent intent = new Intent(this, AlarmReceiver.class);
// 创建封装BroadcastReceiver的pendingIntent对象
PendingIntent pendingIntent = PendingIntent.
getBroadcast(this, 0,intent, 0);
// 开始定时器，每1分钟执行一次
alarmManager.setRepeating(AlarmManager.RTC,
0, 60 * 1000, pendingIntent);
}
}

在使用本例添加若干个时间点后，会在alarm_record.xml文件中看到类似下面的内容：
<?xml version='1.0' encoding='utf-8' standalone='yes' ?>
<map>
<string name="18:52">18:52</string>
<string name="20:16">20:16</string>
<string name="19:11">19:11</string>
<string name="19:58">19:58</string>
<string name="22:51">22:51</string>
<string name="22:10">22:10</string>
<string name="22:11">22:11</string>
<string name="20:10">20:10</string>
</map>

上面每个<string>元素都是一个时间点，定时器将每隔1分钟查一次alarm_record.xml文件。