RemoteView中的应用除了有通知栏的自定义之外，还有桌面小部件也是通过RemoteView以及AppWidgetProvider来完成的。

实际上AppWidgetProvider是一个广播，即继承于BroadcastReceiver。

public class AppWidgetProvider extends BroadcastReceiver

那么我们其实可以将AppWidgetProvider当成一个特殊的BroadcastReceiver就可以了。

让我们来自定义一个桌面小部件：

首先现在res/layout/ 下创建一个xml文件，命名为appwidget.xml，这个就代表着小部件的样子是什么：

android:layout_width="match_parent"

android:layout_height="match_parent"

android:orientation="vertical" >

android:layout_width="wrap_content"

android:layout_height="wrap_content"

android:src="@drawable/icon1" />

LinearLayout>

接着我们在res/xml下创建appwidget_provider_info.xml：

android:initialLayout="@layout/appwidget"

android:minHeight="84dp"

android:minWidth="84dp"

android:updatePeriodMillis="86400000" >

appwidget-provider>

在上面第一个属性是指小工具使用的初始化布局。第二属性和第三个属性是指最小的宽高，最后一个属性是指更新周期，每隔这么多秒就会被触发。

下面是实现类，要继承于AppWidgetProvider：

public class AppProvider extends AppWidgetProvider{

public static final String TAG = "MyAppProvider";

public static final String CLICK_ACTION = "com.example.remoteview.action.CLICK";

public AppProvider(){

super();

}

//同样是要重写onReceive()

@Override

public void onReceive(final Context context,Intent intent){

super.onReceive(context, intent);

Log.e(TAG, "action = " + intent.getAction());

if(intent.getAction().equals(CLICK_ACTION)){

Toast.makeText(context, "click it", Toast.LENGTH_SHORT).show();

new Thread(new Runnable() {

@Override

public void run() {

// TODO Auto-generated method stub

//建立Bitmap

Bitmap srcBitmap = BitmapFactory.decodeResource(context.getResources(), R.drawable.icon1);

//声明AppWidgetManager

AppWidgetManager appWidgetManager = AppWidgetManager.getInstance(context);

for(int i = 0;i < 37;i++){

//控件图片旋转360度

float degree = (i * 10)%360;

RemoteViews remoteView = new RemoteViews(context.getPackageName(),R.layout.appwidget);

remoteView.setImageViewBitmap(R.id.imageView1,rotateBitmap(context,srcBitmap,degree));

Intent intentClick = new Intent();

intentClick.setAction(CLICK_ACTION);

PendingIntent pendingIntent = PendingIntent.getBroadcast(context, 0, intentClick, 0);

remoteView.setOnClickPendingIntent(R.id.imageView1,pendingIntent);

//updateAppWidget将会调用onUpdate

appWidgetManager.updateAppWidget(new ComponentName(context, AppProvider.class),remoteView);

SystemClock.sleep(30);

}

}

}).start();

}

}

@Override

public void onUpdate(Context context,AppWidgetManager appWidgetManager,int[] appWidgetIds){

super.onUpdate(context, appWidgetManager, appWidgetIds);

Log.e(TAG, "onUpdate");

final int counter = appWidgetIds.length;

Log.e(TAG, "COUNTER = " + counter);

for(int i = 0;i < counter; i++){

int appWidgetId = appWidgetIds[i];

onWidgetUpdate(context,appWidgetManager,appWidgetId);

}

}

//更新部件函数

private void onWidgetUpdate(Context context,AppWidgetManager appWidgetManager,int appWidgetId){

RemoteViews remoteViews = new RemoteViews(context.getPackageName(),R.layout.appwidget);

Intent intentClick = new Intent();

intentClick.setAction(CLICK_ACTION);

PendingIntent pendingIntent = PendingIntent.getBroadcast(context, 0, intentClick, 0);

//桌面小部件将会被点击触发，发送PendingIntent

remoteViews.setOnClickPendingIntent(R.id.imageView1, pendingIntent);

appWidgetManager.updateAppWidget(appWidgetId, remoteViews);

}

//变换Bitmap的矩阵

private Bitmap rotateBitmap(Context context,Bitmap srcBitmap,float degree){

Matrix matrix = new Matrix();

matrix.reset();

matrix.setRotate(degree);

Bitmap tmpBitmap = Bitmap.createBitmap(srcBitmap,0,0,srcBitmap.getWidth(),srcBitmap.getHeight(),matrix,true);

return tmpBitmap;

}

}

对了，别忘记了还有继承于BroadcastReceiver我们还是需要注册，注册有点点不一样。如下：

android:resource="@xml/appwidget_provider_info">

meta-data>

intent-filter>

receiver>

第一个Action用来标识点击行为，第二个Action是声明为AppWidget必须存在的action。

这样就完成了桌面小工具的实现了。