2.App Components-App Widgets

浏览数：28 / 时间：2015年06月11日

1. App Widgets

　　App Widgets are miniature application views that can be embedded in other applications (such as the Home screen) and receive periodic

　　　　updates. These views are referred to as Widgets in the user interface, and you can publish one with an App Widget provider. An

　　　　application component that is able to hold other App Widgets is called an App Widget host. The screenshot below shows the Music

　　　　App Widget.

2. The Basics

　　To create an App Widgets, you need the following:

　　<1> AppWidgetProviderInfo object

　　　　Describes the metadata for an App Widget, such as the App Widget‘s layout, update frequency, and the AppWidgetProvider class.

　　　　　　This should be defined in XML

　　<2> AppWidgetProvider class implementation

　　　　Defines the basic methods that allow you to programmatically interface with the App Widget, based on broadcast events. Through it,

　　　　　　you will receive broadcasts when the App Widget is updated, enabled, disabled and deleted

　　<3> View Layout

　　　　Defines the initial layout for the App Widget, defined in XML.

3. Declaring an App Widget in the Manifest

<receiver android:name="ExampleAppWidgetProvider" > //specifies the AppWidgetProvider used by the App Widget
    <intent-filter>
        <action android:name="android.appwidget.action.APPWIDGET_UPDATE" />  //specifies that the AppWidgetProvider accepts the
　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　  //ACTION_APPWIDGET_UPDATE broadcast 

    </intent-filter>
    <meta-data android:name="android.appwidget.provider"   //specifies the metadata name
               android:resource="@xml/example_appwidget_info" />   //specifies the AppWidgetProviderInfo resource location
</receiver>