 | Android Widget开发（转） ... by 机器人 ... 20 月 6 天前 ... 177 次点击
本帖最后由 haiyangjy 于 2009-4-21 12:10 编辑
近期Android 1.5 SDK中加入了不少开发框架，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 thisexample, we want our widget to be 2 cells wide and 1 cell tall, whichmeans we should request a minimum size 146dip x 72dip. We're also goingto request updates once per day, which is roughly every 86,400,000milliseconds. 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=".WordWidget" android:label="@string/widget_name">
? ? <intent-filter>
? ?? ???<action android:name="android.appwidget.action.APPWIDGET_UPDATE" />
? ? </intent-filter>
? ? <meta-data android:name="android.appwidget.provider" android:resource="@xml/widget_word" />
</receiver>
<!-- Service to perform web API queries -->
<serviceandroid:name=".WordWidget$UpdateService" />
Finally, let's write theBroadcastReceiver code to actually handle AppWidget requests. To helpwidgets manage all of the various broadcast events, there is a helperclass called AppWidgetProvider, which we'll use here. One veryimportant thing to notice is that we're launching a background serviceto perform the actual update. This is because BroadcastReceivers aresubject to the Application Not Responding (ANR) timer, which may promptusers to force close our app if it's taking too long. Making a webrequest might take several seconds, so we use the service to avoid anyANR timeouts.
/**
* Define a simple widget that shows the Wiktionary "Word 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);
? ?? ?? ?? ?manager.updateAppWidget(thisWidget, updateViews);
? ?? ???}
? ?? ???/**
? ?? ?? ?* Build a widget update to show the current Wiktionary
? ?? ?? ?* "Word of the day." Will block until the online API returns.
? ?? ?? ?*/
? ?? ???public RemoteViews buildUpdate(Context context) {
? ?? ?? ?? ?// Pick out month names from resources
? ?? ?? ?? ?Resources res = context.getResources();
? ?? ?? ?? ?String[] monthNames = res.getStringArray(R.array.month_names);
? ?? ?? ?? ?// Find current month and day
? ?? ?? ?? ?Time today = new Time();
? ?? ?? ?? ?today.setToNow();
? ?? ?? ?? ?// Build today's page title, like "Wiktionary:Word of the day/March 21"
? ?? ?? ?? ?String pageName = res.getString(R.string.template_wotd_title,
? ?? ?? ?? ?? ? monthNames[today.month], today.monthDay);
? ?? ?? ?? ?RemoteViews updateViews = null;
? ?? ?? ?? ?String pageContent = "";
? ?? ?? ?? ?try {
? ?? ?? ?? ?? ? // Try querying the Wiktionary API for today's word
? ?? ?? ?? ?? ? SimpleWikiHelper.prepareUserAgent(context);
? ?? ?? ?? ?? ? pageContent = SimpleWikiHelper.getPageContent(pageName, false);
? ?? ?? ?? ?} catch (ApiException e) {
? ?? ?? ?? ?? ? Log.e("WordWidget", "Couldn't contact API", e);
? ?? ?? ?? ?} catch (ParseException e) {
? ?? ?? ?? ?? ? Log.e("WordWidget", "Couldn't parse API response", e);
? ?? ?? ?? ?}
? ?? ?? ?? ?// Use a regular expression to parse out the word and its definition
? ?? ?? ?? ?Pattern pattern = Pattern.compile(SimpleWikiHelper.WORD_OF_DAY_REGEX);
? ?? ?? ?? ?Matcher matcher = pattern.matcher(pageContent);
? ?? ?? ?? ?if (matcher.find()) {
? ?? ?? ?? ?? ? // Build an update that holds the updated widget contents
? ?? ?? ?? ?? ? updateViews = new RemoteViews(context.getPackageName(), R.layout.widget_word);
? ?
? ?? ?? ?? ?? ? String wordTitle = matcher.group(1);
? ?? ?? ?? ?? ? updateViews.setTextViewText(R.id.word_title, wordTitle);
? ?? ?? ?? ?? ? updateViews.setTextViewText(R.id.word_type, matcher.group(2));
? ?? ?? ?? ?? ? updateViews.setTextViewText(R.id.definition, matcher.group(3).trim());
? ?
? ?? ?? ?? ?? ? // When user clicks on widget, launch to Wiktionary definition page
? ?? ?? ?? ?? ? String definePage = res.getString(R.string.template_define_url,
? ?? ?? ?? ?? ?? ?? ?? ?Uri.encode(wordTitle));
? ?? ?? ?? ?? ? Intent defineIntent = new Intent(Intent.ACTION_VIEW, Uri.parse(definePage));
? ?? ?? ?? ?? ? PendingIntent pendingIntent = PendingIntent.getActivity(context,
? ?? ?? ?? ?? ?? ?? ?? ?0 /* no requestCode */, defineIntent, 0 /* no flags */);
? ?? ?? ?? ?? ? updateViews.setOnClickPendingIntent(R.id.widget, pendingIntent);
? ?
? ?? ?? ?? ?} else {
? ?? ?? ?? ?? ? // Didn't find word of day, so show error message
? ?? ?? ?? ?? ? updateViews = new RemoteViews(context.getPackageName(), R.layout.widget_message);
? ?? ?? ?? ?? ? CharSequence errorMessage = context.getText(R.string.widget_error);
? ?? ?? ?? ?? ? updateViews.setTextViewText(R.id.message, errorMessage);
? ?? ?? ?? ?}
? ?? ?? ?? ?return updateViews;
? ?? ???}
? ?? ???@Override
? ?? ???public IBinder onBind(Intent intent) {
? ?? ?? ?? ?// We don't need to bind to this service
? ?? ?? ?? ?return null;
? ?? ???}
? ? }
}复制代码 | |
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