Android:AlarmManager

AlarmManager

The AlarmManager is intended for cases where you want to have your application code run at a specific time, even if your application is not currently running.

The following little demo is developed to learn about AlarmManager:

1. Manifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.slowalker.alarmdemo"
    android:versionCode="1"
    android:versionName="1.0" >

    <uses-sdk
        android:minSdkVersion="8"
        android:targetSdkVersion="18" />

    <application
        android:allowBackup="true"
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/AppTheme" >
        <activity
            android:name="com.slowalker.alarmdemo.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>
        <service
            android:name="com.slowalker.alarmdemo.PollingService"
            android:label="@string/app_name" >
            <intent-filter>
                <action android:name="com.slowalker.alarmdemo.pollingservice.action"/>
                <category android:name="android.intent.category.DEFAULT"/>
            </intent-filter>
        </service>
    </application>

</manifest>

2. MainActivity.java

package com.slowalker.alarmdemo;

import android.os.Bundle;
import android.app.Activity;
import android.util.Log;
import android.view.Menu;

public class MainActivity extends Activity {

	private static final String TAG = MainActivity.class.getSimpleName();
	
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        if (Switcher.DEBUG) {
        	Log.d(TAG, "onCreate()");
        }
        setContentView(R.layout.activity_main);
        PollingUtils.startPollingService(this, 3, PollingService.class, PollingService.ACTION);
    }

	@Override
	protected void onDestroy() {
		super.onDestroy();
		if (Switcher.DEBUG) {
			Log.d(TAG, "onDestroy()");
		}
		PollingUtils.stopPollingService(this, PollingService.class, PollingService.ACTION);
	}

}

3. PollingUtils.java

package com.slowalker.alarmdemo;

import android.app.AlarmManager;
import android.app.PendingIntent;
import android.content.Context;
import android.content.Intent;
import android.os.SystemClock;

public class PollingUtils {
	/**
	 * Start polling service.
	 * @param context context
	 * @param seconds polling cycle
	 * @param cls classname
	 * @param action action of intent 
	 */
	public static void startPollingService(Context context, int seconds, Class<?> cls, String action) {
		/*Get system service of AlarmManager.*/
		AlarmManager manager = (AlarmManager) context.getSystemService(Context.ALARM_SERVICE);
		/*Set the intent of the polling.*/
		Intent intent = new Intent(context, cls);
		intent.setAction(action);
		PendingIntent pendingIntent = PendingIntent.getService(context, 0, intent, PendingIntent.FLAG_UPDATE_CURRENT);
		/*Get the begin time of tiggering polling.*/
		long triggerAtTime = SystemClock.elapsedRealtime();
		/*Invoke method setRepeating() to implement polling per seconds(in second) time.*/
		manager.setRepeating(AlarmManager.ELAPSED_REALTIME, triggerAtTime, seconds * 1000, pendingIntent);
	}
	/**
	 * Stop polling service.
	 * @param context context
	 * @param cls classname
	 * @param action action of intent 
	 */
	
	public static void stopPollingService(Context context, Class<?> cls, String action) {
		/*Get system service of AlarmManager.*/
		AlarmManager manager = (AlarmManager) context.getSystemService(Context.ALARM_SERVICE);
		/*Set the intent of the polling.*/
		Intent intent = new Intent(context, cls);
		intent.setAction(action);
		PendingIntent pendingIntent = PendingIntent.getService(context, 0, intent, PendingIntent.FLAG_UPDATE_CURRENT);
		/*Invoke method cancel() to cancel the polling.*/
		manager.cancel(pendingIntent);
	}
}

4. PollingService.java

package com.slowalker.alarmdemo;

import android.app.Service;
import android.content.Context;
import android.content.Intent;
import android.os.IBinder;
import android.util.Log;

public class PollingService extends Service {

	private static final String TAG = PollingService.class.getSimpleName();
	public static final String ACTION = "com.slowalker.alarmdemo.pollingservice.action";
	
	@Override
	public IBinder onBind(Intent intent) {
		if (Switcher.DEBUG) {
			Log.d(TAG, "onBind()");
		}
		return null;
	}

	@Override
	public void onCreate() {
		if (Switcher.DEBUG) {
			Log.d(TAG, "onCreate()");
		}
	}

	@Override
	public void onStart(Intent intent, int startId) {
		if (Switcher.DEBUG) {
			Log.d(TAG, "onStart()");
		}
		new Thread(new Runnable() {
			
			@Override
			public void run() {
				if (Switcher.DEBUG) {
					Log.d(TAG, "Polling...");
				}
				System.out.println("polling service works...");
			}
			
		}).start();
	}

	@Override
	public void onDestroy() {
		if (Switcher.DEBUG) {
			Log.d(TAG, "onDestroy()");
		}
	}
}