How To Use A Broadcastreceiver In Web Services

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Use A Broadcast Receiver For Groundwork Services In Android

As an Android developer, you'll often run into the scenario where you lot demand to perform tasks and display notifications for your app in the background.

To retain bombardment power on our users device we are going to run background tasks using a broadcast receiver. This will prevent a thread from constantly running in the background draining the bombardment quickly over time. Instead, the task will be run on defined intervals of the alarm.

                                                                    packet                    com                    .                    nraboy                    .                    instance                    ;                                                                                                                                                            import                    android                    .                    app                    .                    *                    ;                                                                                        import                    android                    .                    content                    .                    *                    ;                                                                                        import                    android                    .                    os                    .                    *                    ;                                                                                                                                                            public                    class                    AlarmReceiver                    extends                    BroadcastReceiver                    {                                                                                                                                                            @                    Override                                                                                        public                    void                    onReceive                    (                    Context                    context                    ,                    Intent                    intent                    )                    {                                                                                        Intent                    background                    =                    new                    Intent                    (                    context                    ,                    BackgroundService                    .                    class                    );                                                                                        context                    .                    startService                    (                    background                    );                                                                                        }                                                                                                                                                            }

The to a higher place code is our broadcast receiver. Every time it is called, our background service is executed.

So how practice we enable our broadcast receiver to work on Android's alert service? That is easy, and can exist seen in the following chunk of code:

                                                                    parcel                    com                    .                    nraboy                    .                    example                    ;                                                                                                                                                            import                    android                    .                    app                    .                    Activity                    ;                                                                                        import                    android                    .                    bone                    .                    *                    ;                                                                                        import                    android                    .                    content                    .                    *                    ;                                                                                        import                    android                    .                    app                    .                    *                    ;                                                                                                                                                            public                    class                    ExampleActivity                    extends                    Activity                    {                                                                                                                                                            private                    Context                    context                    ;                                                                                                                                                            @                    Override                                                                                        public                    void                    onCreate                    (                    Bundle                    savedInstanceState                    )                    {                                                                                        super                    .                    onCreate                    (                    savedInstanceState                    );                                                                                        setContentView                    (                    R                    .                    layout                    .                    master                    );                                                                                        this                    .                    context                    =                    this                    ;                                                                                        Intent                    alarm                    =                    new                    Intent                    (                    this                    .                    context                    ,                    AlarmReceiver                    .                    form                    );                                                                                        boolean                    alarmRunning                    =                    (                    PendingIntent                    .                    getBroadcast                    (                    this                    .                    context                    ,                    0                    ,                    warning                    ,                    PendingIntent                    .                    FLAG_NO_CREATE                    )                    !=                    goose egg                    );                                                                                        if                    (                    alarmRunning                    ==                    fake                    )                    {                                                                                        PendingIntent                    pendingIntent                    =                    PendingIntent                    .                    getBroadcast                    (                    this                    .                    context                    ,                    0                    ,                    alarm                    ,                    0                    );                                                                                        AlarmManager                    alarmManager                    =                    (                    AlarmManager                    )                    getSystemService                    (                    Context                    .                    ALARM_SERVICE                    );                                                                                        alarmManager                    .                    setRepeating                    (                    AlarmManager                    .                    ELAPSED_REALTIME_WAKEUP                    ,                    SystemClock                    .                    elapsedRealtime                    (),                    1800000                    ,                    pendingIntent                    );                                                                                        }                                                                                        }                                                                                                                                                            }

The above lawmaking will prepare our circulate receiver and then cheque to see if it is already running. If it is already running, do naught because we don't want to register it multiple times. If the receiver is not already running, nosotros volition register information technology to repeat every 1800000 milliseconds, or every thirty minutes.

And so what exactly is the broadcast receiver doing when information technology wakes up? It is just calling our background service intent where nosotros exercise all of our heavy lifting.

                                                                    package                    com                    .                    nraboy                    .                    example                    ;                                                                                                                                                            import                    android                    .                    app                    .                    *                    ;                                                                                        import                    android                    .                    content                    .                    *                    ;                                                                                        import                    android                    .                    os                    .                    *                    ;                                                                                                                                                            public                    class                    BackgroundService                    extends                    Service                    {                                                                                                                                                            private                    boolean                    isRunning                    ;                                                                                        private                    Context                    context                    ;                                                                                                                                                            @                    Override                                                                                        public                    IBinder                    onBind                    (                    Intent                    intent                    )                    {                                                                                        return                    null                    ;                                                                                        }                                                                                                                                                            @                    Override                                                                                        public                    void                    onCreate                    ()                    {                                                                                        this                    .                    context                    =                    this                    ;                                                                                        this                    .                    isRunning                    =                    imitation                    ;                                                                                        this                    .                    backgroundThread                    =                    new                    Thread                    (                    myTask                    );                                                                                        }                                                                                                                                                            private                    Runnable                    myTask                    =                    new                    Runnable                    ()                    {                                                                                        public                    void                    run                    ()                    {                                                                                        // Do something here                                                                                                                                stopSelf                    ();                                                                                        }                                                                                        };                                                                                                                                                            @                    Override                                                                                        public                    void                    onDestroy                    ()                    {                                                                                        this                    .                    isRunning                    =                    false                    ;                                                                                        }                                                                                                                                                            @                    Override                                                                                        public                    int                    onStartCommand                    (                    Intent                    intent                    ,                    int                    flags                    ,                    int                    startId                    )                    {                                                                                        if                    (!                    this                    .                    isRunning                    )                    {                                                                                        this                    .                    isRunning                    =                    true                    ;                                                                                        this                    .                    backgroundThread                    .                    start                    ();                                                                                        }                                                                                        return                    START_STICKY                    ;                                                                                        }                                                                                                                                                            }

You can come across in the to a higher place code that all of our variables get initialized in the onCreate and the service starts to run in the onStartCommand method. To prevent the users device from blowing up, all service work is going to be done in a thread. When the thread is complete, the service volition exist stopped until the circulate receiver fires it up over again. You lot'll likewise discover that the service thread will non re-burn if the service is already running. We wouldn't want threads to get jammed up and cease up with 100 running in the background. Your users wouldn't be too pleased with this.

To tie everything together, you need to add the circulate receiver and background service to your AndroidManifest.xml file. The following lines must be added to your file:

                                                <application>                                                                                        <service android:name=".BackgroundService" />                                                                                        <receiver android:name="AlarmReceiver"></receiver>                                                                    </application>

And so why might you desire to utilise a circulate receiver and background service? Well, if you ever want to brandish notifications to your user based on events or calculations yous're going to need to do this from the background. You can for example have your background service execute a RESTful asking to a web service and display a notification depending on the response. Or maybe only update your apps database in the groundwork and so users don't need to wait when they open their application. There are many different possibilities.

A video version of this article can be seen below.

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Nic Raboy

Nic Raboy is an advocate of modern spider web and mobile development technologies. He has feel in Java, JavaScript, Golang and a diversity of frameworks such equally Angular, NativeScript, and Apache Cordova. Nic writes most his development experiences related to making web and mobile development easier to empathize.