Android App Widget 设计

1.App Widget的UI，xml布局文件

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent" >

    <ImageView
        android:id="@+id/iv_weather"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentLeft="true"
        android:layout_alignParentTop="true"
        android:src="@drawable/w_default" />

    <TextView
        android:id="@+id/tv_city"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignBottom="@+id/iv_weather"
        android:layout_alignRight="@+id/iv_weather"
        android:text="时间"
        tools:context=".MainActivity" />

</RelativeLayout>

2.设置App Widget的属性，在res/xml下新建appwidget_provider.xml

<?xml version="1.0" encoding="utf-8"?>
<appwidget-provider xmlns:android="http://schemas.android.com/apk/res/android"  
    android:minWidth="85dp"  
    android:minHeight="30dp"  
    android:updatePeriodMillis="1000"  
    android:initialLayout="@layout/activity_main" >  
</appwidget-provider>

3.编写App Widget的主程序

public class MainActivity extends AppWidgetProvider {

	@Override
	public void onUpdate(Context context, AppWidgetManager appWidgetManager,
			int[] appWidgetIds) {
		super.onUpdate(context, appWidgetManager, appWidgetIds);
		RemoteViews views = new RemoteViews(context.getPackageName(), R.layout.activity_main);//获取RemoteViews对象
	    String time = new Date().toLocaleString();
        views.setTextViewText(R.id.tv_city, time);  
        appWidgetManager.updateAppWidget(appWidgetIds, views);//更新widget
	}
}

4.编辑AndroidManifest.xml

<application
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/AppTheme" >
        <receiver android:name=".MainActivity" >  
            <meta-data  
                android:name="android.appwidget.provider"  
                android:resource="@xml/appwidget_provider" />  
            <intent-filter>  
                <action android:name="android.appwidget.action.APPWIDGET_UPDATE" />  
            </intent-filter>  
        </receiver>
    </application>

最后效果图：