【Android】創建桌面widget

創建一個widget需要一下步驟：

1、在AndroidManifest文件中聲明應用的appwidget

<receiver android:name="ExampleAppWidgetProvider" >
    <intent-filter>
        <action android:name="android.appwidget.action.APPWIDGET_UPDATE" />
    </intent-filter>
    <meta-data android:name="android.appwidget.provider"
               android:resource="@xml/example_appwidget_info" /> <!-- 這個佈局文件是用來控制桌面上widget佈局的 -->
</receiver>

2、讀取example_appwidget_info中的配置信息

<appwidget-provider xmlns:android="http://schemas.android.com/apk/res/android"
    android:minWidth="294dp"
    android:minHeight="72dp"
    android:updatePeriodMillis="86400000" <!-- 用來控制3中onUpate的刷新時間-->
    android:previewImage="@drawable/preview" <!-- 在桌面長按後得到的列表中的圖標-->
    android:initialLayout="@layout/example_appwidget"
    android:configure="com.example.android.ExampleAppWidgetConfigure" <!-- 下一步啓動的activity-->    
    android:resizeMode="horizontal|vertical">
</appwidget-provider>

3、AppWidgetProvider 初始化widget，當一個應用有多個widget時需要在這個處理一下，一般在onUpate不做過多的操作，而是啓動一個config activity來做配置操作

public class ExampleAppWidgetProvider extends AppWidgetProvider {

    public void onUpdate(Context context, AppWidgetManager appWidgetManager, int[] appWidgetIds) {
        final int N = appWidgetIds.length;

        // Perform this loop procedure for each App Widget that belongs to this provider
        for (int i=0; i<N; i++) {
            int appWidgetId = appWidgetIds[i];
	/*
            // Create an Intent to launch ExampleActivity
            Intent intent = new Intent(context, ExampleActivity.class);
            PendingIntent pendingIntent = PendingIntent.getActivity(context, 0, intent, 0);

            // Get the layout for the App Widget and attach an on-click listener
            // to the button
            RemoteViews views = new RemoteViews(context.getPackageName(), R.layout.appwidget_provider_layout);
            views.setOnClickPendingIntent(R.id.button, pendingIntent);

            // Tell the AppWidgetManager to perform an update on the current app widget
            appWidgetManager.updateAppWidget(appWidgetId, views);	這部分代碼可拿到config activity中做*/
        }
    }
}

<activity android:name=".ExampleAppWidgetConfigure">
    <intent-filter>
        <action android:name="android.appwidget.action.APPWIDGET_CONFIGURE"/>
    </intent-filter>
</activity>

4、ExampleAppWidgetConfigure（config activity）

<activity android:name=".ExampleAppWidgetConfigure">
    <intent-filter>
        <action android:name="android.appwidget.action.APPWIDGET_CONFIGURE"/>
    </intent-filter>
</activity>

Intent intent = getIntent();
Bundle extras = intent.getExtras();
if (extras != null) {
    mAppWidgetId = extras.getInt(
            AppWidgetManager.EXTRA_APPWIDGET_ID, 
            AppWidgetManager.INVALID_APPWIDGET_ID);
}

AppWidgetManager appWidgetManager = AppWidgetManager.getInstance(context);

RemoteViews views = new RemoteViews(context.getPackageName(),
R.layout.example_appwidget);
appWidgetManager.updateAppWidget(mAppWidgetId, views);

Intent resultValue = new Intent();
resultValue.putExtra(AppWidgetManager.EXTRA_APPWIDGET_ID, mAppWidgetId);
setResult(RESULT_OK, resultValue);
finish();