Application Widget lecture 1 (Android Learning Guide)

 

Steps for implementing the App Widget:

 

A. Create an AppWidgetProvider object and define it by using XML (appwidgetinfo. xml:

 

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<? Xml version = "1.0" encoding = "UTF-8"?>

<Appwidget-provider

Xmlns: android = "http://schemas.android.com/apk/res/android"

Android: minWidth = "294dp"

Android: minHeight = "72dp"

Android: updatePeriodMillis = "86400000"

Android: initialLayout = "@ layout/awl"

>

</Appwidget-provider>

Defines the minimum width, minimum height, update period, and initial layout of the AppWidget.

 

The initial layout file (awl. xml) of the AppWidget is as follows:

 

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<? Xml version = "1.0" encoding = "UTF-8"?>

<LinearLayout

Xmlns: android = "http://schemas.android.com/apk/res/android"

Android: layout_width = "fill_parent"

Android: layout_height = "fill_parent"

Android: orientation = "vertical">

<TextView android: id = "@ + id/TV"

Android: layout_width = "fill_parent"

Android: layout_height = "wrap_content"

Android: text = "test"/>

<Button android: id = "@ + id/btn"

Android: layout_width = "fill_parent"

Android: layout_height = "wrap_content"

Android: text = "click"/>

</LinearLayout>

B. Implement the AppWidgetProvider class (AWTProvider. java ):

 

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Package yc. yc;

 

Import android. app. PendingIntent;

Import android. appwidget. AppWidgetManager;

Import android. appwidget. AppWidgetProvider;

Import android. content. Context;

Import android. content. Intent;

Import android. widget. RemoteViews;

 

Public class AWTProvider extends AppWidgetProvider {

 

// Every time an AppWidget is deleted, the onDeleted method is called.

@ Override

Public void onDeleted (Context context, int [] appWidgetIds ){

System. out. println ("delete ");

Super. onDeleted (context, appWidgetIds );

}

 

// When the last AppWidget is deleted, the onDisabled method is called.

// In this method, terminate some AppWidget operations, such as deleting a temporary database.

@ Override

Public void onDisabled (Context context ){

System. out. println ("disable ");

Super. onDisabled (context );

}

// When the first AppWidget instance is created, the onEnabled method is called.

// In this method, initialize some AppWidget, such as creating a database or performing some operations.

@ Override

Public void onEnabled (Context context ){

System. out. println ("enable ");

Super. onEnabled (context );

}

// OnReceive is equivalent to a manager. When an external task comes, the task is distributed to its employees (onEnable, onDeleted, onDisabled, onUpdate) for processing.

@ Override

Public void onReceive (Context context, Intent intent ){

System. out. println ("receive ");

Super. onReceive (context, intent );

}

 

// Here, there are two conditions for onUpdate execution: 1. The update cycle is set; 2. Add a new AppWidget.

// In onUpdate, event processing is defined for the control or a temporary Service is enabled.

// Here is how to add a click event for our button control.

// Context indicates the environment in which the receiver is running

// AppWManager indicates that the AppWidget manager can change the control attributes of a specified AppWidget by calling updateAppWidget (ComponentName, RemoteViews ).

// AppWidgetIds indicates the Appwidget ID, which is automatically generated by the system.

@ Override

Public void onUpdate (Context context, AppWidgetManager appWidgetManager,

Int [] appWidgetIds ){

System. out. println ("update ");

Final int N = appWidgetIds. length;

For (int I = 0; I <N; I ++ ){

Int appWidgetId = appWidgetIds [I];

System. out. println ("appWidgetId =" + appWidgetId );

Intent intent = new Intent (context, AWTActivity. class );

PendingIntent pendingIntent = PendingIntent. getActivity (context, 0, intent, 0 );

RemoteViews views = new RemoteViews (context. getPackageName (), R. layout. awl );

Views. setOnClickPendingIntent (R. id. btn, pendingIntent );

AppWidgetManager. updateAppWidget (appWidgetId, views );

}

}

 

}

C. register the implementation class in AndroidManifest. xml and define metadata:

 

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<? Xml version = "1.0" encoding = "UTF-8"?>

<Manifest xmlns: android = "http://schemas.android.com/apk/res/android"

Package = "yc. yc"

Android: versionCode = "1"

Android: versionName = "1.0" type = "codeph" text = "/codeph">

<Uses-sdk android: minSdkVersion = "7"/>

 

<Application android: icon = "@ drawable/icon" android: label = "@ string/app_name">

<Activity android: name = ". AWTActivity"

Android: label = "@ string/app_name">

<Intent-filter>

<Action android: name = "android. intent. action. MAIN"/>

<Category android: name = "android. intent. category. LAUNCHER"/>

</Intent-filter>

</Activity>

<! -- Register the implementation class -->

<Explorer android: name = ". AWTProvider">

<Intent-filter>

<Action android: name = "android. appwidget. action. APPWIDGET_UPDATE"/>

</Intent-filter>

<! -- Define metadata -->

<Meta-data android: name = "android. appwidget. provider"

Android: resource = "@ xml/appwidgetinfo"/>

</Cycler>

</Application>

</Manifest>

 

Note: This is only the first lecture of AppWidget and the subsequent courses.

 

From tianshijianbing1989