先看两段日志：
（1）日志打印的是18点19分18秒的信息。
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11-21 18:19:18.587: V/TvRemindReceiver(29899): @onReceive. action >> tvie.intent.action.REMIND
11-21 18:19:18.597: V/TvRemindReceiver(29899): @onRemind. cursor.count >> 3
11-21 18:19:18.647: V/TvRemindReceiver(29899): @remind. notify user to watch TV. notificationId is >> 4
11-21 18:19:18.647: V/TvRemindReceiver(29899): @remind. notify user to watch TV. message is >> 《蓝筹进行时》还有5分钟就开始播放。
11-21 18:19:18.707: V/TvRemindReceiver(29899): @remind. notify user to watch TV. notificationId is >> 5
11-21 18:19:18.707: V/TvRemindReceiver(29899): @remind. notify user to watch TV. message is >> 《理财晚餐》还有5分钟就开始播放。
11-21 18:19:18.717: V/TvRemindReceiver(29899): @remind. notify user to watch TV. notificationId is >> 6
11-21 18:19:18.717: V/TvRemindReceiver(29899): @remind. notify user to watch TV. message is >> 《中国基金报道》还有5分钟就开始播放。（2）日志打印的是18点20分18秒的信息。
11-21 18:20:18.587: V/TvRemindReceiver(29899): @onReceive. action >> tvie.intent.action.REMIND
11-21 18:20:18.597: V/TvRemindReceiver(29899): @onRemind. cursor.count >> 3
11-21 18:20:18.627: V/TvRemindReceiver(29899): @remind. notify user to watch TV. notificationId is >> 7
11-21 18:20:18.627: V/TvRemindReceiver(29899): @remind. notify user to watch TV. message is >> 《蓝筹进行时》还有5分钟就开始播放。
11-21 18:20:18.677: V/TvRemindReceiver(29899): @remind. notify user to watch TV. notificationId is >> 8
11-21 18:20:18.677: V/TvRemindReceiver(29899): @remind. notify user to watch TV. message is >> 《理财晚餐》还有5分钟就开始播放。
11-21 18:20:18.677: V/TvRemindReceiver(29899): @remind. notify user to watch TV. notificationId is >> 9
11-21 18:20:18.677: V/TvRemindReceiver(29899): @remind. notify user to watch TV. message is >> 《中国基金报道》还有5分钟就开始播放。显然以上两段日志是相隔1分钟打印出来的，日志显示程序逻辑没有说明问题。
以下是程序的实现
public class TvRemindReceiver extends BroadcastReceiver {
public static final String ACTION_REMIND = "tvie.intent.action.REMIND";
public static final String ACTION_LAUNCH = "tvie.intent.action.LAUNCH";
public static final int TYPE_REMIND = 1;
public static final int TYPE_LAUNCH = 2;
private String TAG = "TvRemindReceiver";
private static int notificationId = 0;
@Override
public void onReceive(Context context, Intent intent) {
String action = intent.getAction();
Logger.v(TAG, "@onReceive. action >> " + action);
if(action == null) return;
if (action.equals(Intent.ACTION_BOOT_COMPLETED)) {
onBootCompleted(context);
} else if (action.equals(ACTION_LAUNCH)) {
onBootCompleted(context);
} else if (action.equals(ACTION_REMIND)) {
onRemind(context);
}
}
private void onBootCompleted(Context context) {
Logger.v(TAG, "@onBootCompleted.");
AlarmManager am = (AlarmManager) context.getSystemService(Context.ALARM_SERVICE);
Intent intent = new Intent(context, TvRemindReceiver.class);
intent.setAction(ACTION_REMIND);
PendingIntent operation = PendingIntent.getBroadcast(context, 0, intent, 0);
long triggerAtMillis = SystemClock.elapsedRealtime();
am.setRepeating(TYPE_REMIND, triggerAtMillis, 60 * 1000, operation);
}
public int getCursorCount(Cursor cursor) {
int count = 0;
while(cursor.moveToNext()) {
count++;
}
return count;
}
private void onRemind(Context context) {
Cursor cursor = context.getContentResolver().query(DataProvider.getUri(), null,
SimpleDataColumns.MODULE + "= ? ", new String[] { Constants.PROGRAM }, null);
TvRemind tvRemind = null;
Logger.v(TAG, "@onRemind. cursor.count >> " + getCursorCount(cursor));
if(cursor.moveToFirst()) {
do{
String programId = cursor.getString(cursor.getColumnIndex(SimpleDataColumns.KEY));
String time = cursor.getString(cursor.getColumnIndex(SimpleDataColumns.DATA1));
String name = cursor.getString(cursor.getColumnIndex(SimpleDataColumns.DATA2));
tvRemind = new TvRemind(time, name, programId);
remind(context, R.drawable.ic_launcher, "节目提醒", "《" + tvRemind.getName() + "》还有5分钟就开始播放。");
}while(cursor.moveToNext());
}
cursor.close();
}
@SuppressWarnings("deprecation")
private void remind(Context context, int icon, String title, String text) {
Notification notifaction = new Notification();
notifaction.icon = icon;
notifaction.tickerText = text;
notifaction.when = System.currentTimeMillis();
notifaction.defaults = Notification.DEFAULT_ALL;
Intent it = new Intent(context, MainActivity.class);
PendingIntent operation = PendingIntent.getBroadcast(context, notificationId, it,
PendingIntent.FLAG_UPDATE_CURRENT);
notifaction.setLatestEventInfo(context, title, text, operation);
NotificationManager nm = (NotificationManager) context.getSystemService(Context.NOTIFICATION_SERVICE);
nm.notify(++notificationId, notifaction);
Logger.v(TAG, "@remind. notify user to watch TV. notificationId is >> " + notificationId);
Logger.v(TAG, "@remind. notify user to watch TV. message is >> " + text);
}
}在以上程序中执行了语句：
am.setRepeating(TYPE_REMIND, triggerAtMillis, 60 * 1000, operation);这条语句表示启动一个闹钟服务，每隔60秒执行一次操作。这个闹钟服务与具体应用无关。即使应用启动后又完全退出，这个闹钟服务还是运行的。
问题：如果下次应用再启动，还会不会再启动一个闹钟服务呢？如何判断闹钟服务是否已经运行，如何避免多次启动相同的闹钟服务呢？
参考：1. AlarmManager(全局定时器/闹钟）指定时长或以周期形式执行某项操作
http://www.cnblogs.com/jico/archive/2010/11/03/1868361.html
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