AppWidget framework在Android桌面开发Widget小工具

  次阅读 作者:智能小宝 来源:互联网 2015-10-03 10:39 我要评论(0)

AppWidget framework 可以方便的在Android桌面上开发Widget小工具,在过去我们已经看到了Live Folder中,下面就以Google官方的一个例子来做介绍吧.

首先我们需要计算下最小高度, 默认情况下Android桌面使用的是基于网格的布局,使用下面的公式可以很好的处理:

Minimum size in dip = (Number of cells * 74dip)2dipIn this example, we want our widget to be 2 cells wide and 1 cell tall, which means we should request a minimum size 146dip x 72dip. We re also going to request updates once per day, which is roughly every 86,400,000 milliseconds. Here s what our widget XML metadata looks like:

<appwidget-provider

xmlns:android= http://schemas.android.com/apk/res/android

android:minWidth= 146dip

android:minHeight= 72dip

android:initialLayout= @layout/widget_message

android:updatePeriodMillis= 86400000

/>

Next, let s pair this XML metadata with a BroadcastReceiver in the AndroidManifest:

<!Broadcast Receiver that will process AppWidget updates>

<receiver android:name= .WordWidgetandroid:label= @string/widget_name >

<intent-filter>

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

</intent-filter>

<meta-data android:name= android.appwidget.providerandroid:resource= @xml/widget_word/>

</receiver>

<!Service to perform web API queries>

<service android:name= .WordWidget$UpdateService/>

Finally, let s write the BroadcastReceiver code to actually handle AppWidget requests. To help widgets manage all of the various broadcast events, there is a helper class called AppWidgetProvider, which we ll use here. One very important thing to notice is that we re launching a background service to perform the actual update. This is because BroadcastReceivers are subject to the Application Not Responding (ANR) timer, which may prompt users to force close our app if it s taking too long. Making a web request might take several seconds, so we use the service to avoid any ANR timeouts.

/**

* Define a simple widget that shows the WiktionaryWord of the day.To build

* an update we spawn a background {@link Service} to perform the API queries.

*/

public class WordWidget extends AppWidgetProvider {

@Override

public void onUpdate(Context context, AppWidgetManager appWidgetManager,

int[] appWidgetIds) {

// To prevent any ANR timeouts, we perform the update in a service

context.startService(new Intent(context, UpdateService.class));

}

public static class UpdateService extends Service {

@Override

public void onStart(Intent intent, int startId) {

// Build the widget update for today

RemoteViews updateViews = buildUpdate(this);

// Push update for this widget to the home screen

ComponentName thisWidget = new ComponentName(this, WordWidget.class);

AppWidgetManager manager = AppWidgetManager.getInstance(this);

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