民企品牌建设/淄博网站制作优化

虽然alarm的意思是闹钟，而且在原生android自带的闹钟应用中AlarmManager也确实非常重要，但并不代表AlarmManager只是用来做闹钟应用的，作为一个一种系统级别的提示服务，肯定应该有着非常重要的地位，实际上android中很多东西都可以利用AlarmManager来实现。

AlarmManager在特定的时刻为我们广播一个指定的Intent。简单的说就是我们设定一个时间，然后在该时间到来时，AlarmManager为我们广播一个我们设定的Intent。这个intent可以指向一个activity，也可以指向一个service。

下面就是使用alarm定时调用service实现轮询的实现方法：

一、新建轮询工具类PollingUtils.java

public class PollingUtils {

//开启轮询服务

public static void startPollingService(Context context, int seconds, Class> cls,String action) {

//获取AlarmManager系统服务

AlarmManager manager = (AlarmManager) context

.getSystemService(Context.ALARM_SERVICE);

//包装需要执行Service的Intent

Intent intent = new Intent(context, cls);

intent.setAction(action);

PendingIntent pendingIntent = PendingIntent.getService(context, 0,

intent, PendingIntent.FLAG_UPDATE_CURRENT);

//触发服务的起始时间

long triggerAtTime = SystemClock.elapsedRealtime();

//使用AlarmManger的setRepeating方法设置定期执行的时间间隔(seconds秒)和需要执行的Service

manager.setRepeating(AlarmManager.ELAPSED_REALTIME, triggerAtTime,

seconds * 1000, pendingIntent);

}

//停止轮询服务

public static void stopPollingService(Context context, Class> cls,String action) {

AlarmManager manager = (AlarmManager) context

.getSystemService(Context.ALARM_SERVICE);

Intent intent = new Intent(context, cls);

intent.setAction(action);

PendingIntent pendingIntent = PendingIntent.getService(context, 0,

intent, PendingIntent.FLAG_UPDATE_CURRENT);

//取消正在执行的服务

manager.cancel(pendingIntent);

}

}

二、构建轮询任务执行PollingService.java

public class PollingService extends Service {

public static final String ACTION = "com.ryantang.service.PollingService";

private Notification mNotification;

private NotificationManager mManager;

@Override

public IBinder onBind(Intent intent) {

return null;

}

@Override

public void onCreate() {

initNotifiManager();

}

@Override

public void onStart(Intent intent, int startId) {

new PollingThread().start();

}

//初始化通知栏配置

private void initNotifiManager() {

mManager = (NotificationManager) getSystemService(NOTIFICATION_SERVICE);

int icon = R.drawable.ic_launcher;

mNotification = new Notification();

mNotification.icon = icon;

mNotification.tickerText = "New Message";

mNotification.defaults |= Notification.DEFAULT_SOUND;

mNotification.flags = Notification.FLAG_AUTO_CANCEL;

}

//弹出Notification

private void showNotification() {

mNotification.when = System.currentTimeMillis();

//Navigator to the new activity when click the notification title

Intent i = new Intent(this, MessageActivity.class);

PendingIntent pendingIntent = PendingIntent.getActivity(this, 0, i,

Intent.FLAG_ACTIVITY_NEW_TASK);

mNotification.setLatestEventInfo(this,

getResources().getString(R.string.app_name), "You have new message!", pendingIntent);

mManager.notify(0, mNotification);

}

/**

* Polling thread

* 模拟向Server轮询的异步线程

* @Author Ryan

* @Create 2013-7-13 上午10:18:34

*/

int count = 0;

class PollingThread extends Thread {

@Override

public void run() {

System.out.println("Polling...");

count ++;

//当计数能被5整除时弹出通知

if (count % 5 == 0) {

showNotification();

System.out.println("New message!");

}

}

}

@Override

public void onDestroy() {

super.onDestroy();

System.out.println("Service:onDestroy");

}

}

三、AndroidManifest.xml 配置

android:name="com.ryantang.service.PollingService"

android:exported="false">

四、在MainActivity.java中开启和停止PollingService

public class MainActivity extends Activity {

@Override

protected void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.activity_main);

//Start polling service

System.out.println("Start polling service...");

PollingUtils.startPollingService(this, 5, PollingService.class, PollingService.ACTION);

}

@Override

protected void onDestroy() {

super.onDestroy();

//Stop polling service

System.out.println("Stop polling service...");

PollingUtils.stopPollingService(this, PollingService.class, PollingService.ACTION);

}

}