AppWidgetProvider是android中提供的用于显示桌面小部件的类，其本质是一个广播，其继承了BroadcastReceiver，在实际应用中把他当做一个BroadcastReceiver就可以了。
1.定义类MyAppWidgetProvider继承AppWidgetProvider
public class MyAppWidgetProvider extends AppWidgetProvider { public static final String TAG = "MyAppWidgetProvider"; public static final String CLICK_ACTION = "android.andyidea.widget"; @Override public void onReceive(final Context context, Intent intent) { super.onReceive(context, intent); Log.i(TAG, "onReceive=" + intent.getAction()); if(intent.getAction().equals(CLICK_ACTION)){ Toast.makeText(context,"click it",Toast.LENGTH_SHORT).show(); new Thread(){ @Override public void run() { Bitmap bitmap = BitmapFactory.decodeResource(context.getResources(), R.drawable.notification); AppWidgetManager appWidgetManager = AppWidgetManager.getInstance(context); for(int i=0;i<37;i++){ float degree = (i*10)%360; RemoteViews remoteViews = new RemoteViews(context.getPackageName(),R.layout.widget); remoteViews.setImageViewBitmap(R.id.imageView, rotateBitmap(context, bitmap, degree)); Intent intentClick = new Intent(); intentClick.setAction(CLICK_ACTION); PendingIntent pendingIntent = PendingIntent.getBroadcast(context,0,intentClick,0); remoteViews.setOnClickPendingIntent(R.id.imageView,pendingIntent); appWidgetManager.updateAppWidget(new ComponentName(context, MyAppWidgetProvider.class), remoteViews); SystemClock.sleep(30); } } }.start(); } } @Override public void onUpdate(Context context, AppWidgetManager appWidgetManager, int[] appWidgetIds) { super.onUpdate(context, appWidgetManager, appWidgetIds); final int counter = appWidgetIds.length; for (int i=0;i<counter;i++){ int appWidgetId = appWidgetIds[i]; onWidgetUpdate(context,appWidgetManager,appWidgetId); } } private void onWidgetUpdate(Context context, AppWidgetManager appWidgetManager, int appWidgetId) { Log.i(TAG,"appWidgetId="+appWidgetId); RemoteViews remoteViews = new RemoteViews(context.getPackageName(),R.layout.widget); Intent intent = new Intent(); intent.setAction(CLICK_ACTION); PendingIntent pendingIntent = PendingIntent.getBroadcast(context,0,intent,0); remoteViews.setOnClickPendingIntent(R.id.imageView,pendingIntent); appWidgetManager.updateAppWidget(appWidgetId,remoteViews); } private Bitmap rotateBitmap(Context context, Bitmap bitmap, float degree) { Matrix matrix = new Matrix(); matrix.reset(); matrix.setRotate(degree); Bitmap tmpBitmap = Bitmap.createBitmap(bitmap,0,0,bitmap.getWidth(),bitmap.getHeight(),matrix,true); return tmpBitmap; } } 上面的代码是在桌面上显示一张图片，点击它后，这个图片会旋转一周，当小部件添加到桌面后，会通过RemoteViews来加载布局文件，而当小部件被单击后的旋转效果是通过不断的更新RemoteViews来实现的，由此可见，桌面小部件不管是初始化界面还是后续的更新都必须使用 RemoteViews来实现。
2.定义小部件的配置信息
在res/xml下新建
<?xml version="1.0" encoding="utf-8"?> <appwidget-provider xmlns:android="http://schemas.android.com/apk/res/android" android:minHeight="84dp" android:minWidth="84dp" android:updatePeriodMillis="86400000" android:initialLayout="@layout/widget"> </appwidget-provider>initialLayout就是指小部件所使用的初始化布局updatePeriodMillis是定义小工具的自动更新周期，没更新一次就调用一次onUpdate方法。 3.定义小部件界面
在res/layout下新建
<?xml version="1.0" encoding="utf-8"?> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:orientation="vertical" android:layout_width="match_parent" android:layout_height="match_parent"> <ImageView android:id="@+id/imageView" android:layout_width="wrap_content" android:layout_height="wrap_content" android:src="@drawable/notification"/> </LinearLayout>4.manifest中声明 <receiver android:name=".appwidgetmanager.MyAppWidgetProvider"> <meta-data android:name="android.appwidget.provider" android:resource="@xml/appwidget_provider_indo"/> <intent-filter> <action android:name="android.appwidget.action.APPWIDGET_UPDATE"/> <action android:name="android.andyidea.widget"/> </intent-filter> </receiver>上面的两个action，其中第二个action用于识别小部件的单击行为，而第一个action则作为小部件的标识必须存在，如果不加那么就是普通的广播，系统不会认为是一个桌面小部件，也不会出现在手机的小部件列表里面了。5.AppWidgetProvider出了常用的onUpdate方法，还有几个其他方法，下面介绍下这几个常用的方法：
onReceive：这是广播的内置方法，用于分发具体的事件给其他方法。
onEnable：当窗口小部件第一次添加到桌面时调用该方法，小部件可以添加多次，但只在第一次调用。
onUpdate：小部件被添加时或者每次小部件更新时都会调用一次该方法，更新时间由updatePeriodMillis来指定，每个周期小部件都会自动更新一次。
onDisabled：当最后一个该类型的桌面小部件被删除时调用该方法，这里是最后一个。
onDeleted：每删除一个桌面小部件就调用一次。
通过下面源码我们可以看出onReceive的分发过程。
public void onReceive(Context context, Intent intent) { // Protect against rogue update broadcasts (not really a security issue, // just filter bad broacasts out so subclasses are less likely to crash). String action = intent.getAction(); if (AppWidgetManager.ACTION_APPWIDGET_UPDATE.equals(action)) { Bundle extras = intent.getExtras(); if (extras != null) { int[] appWidgetIds = extras.getIntArray(AppWidgetManager.EXTRA_APPWIDGET_IDS); if (appWidgetIds != null && appWidgetIds.length > 0) { this.onUpdate(context, AppWidgetManager.getInstance(context), appWidgetIds); } } } else if (AppWidgetManager.ACTION_APPWIDGET_DELETED.equals(action)) { Bundle extras = intent.getExtras(); if (extras != null && extras.containsKey(AppWidgetManager.EXTRA_APPWIDGET_ID)) { final int appWidgetId = extras.getInt(AppWidgetManager.EXTRA_APPWIDGET_ID); this.onDeleted(context, new int[] { appWidgetId }); } } else if (AppWidgetManager.ACTION_APPWIDGET_OPTIONS_CHANGED.equals(action)) { Bundle extras = intent.getExtras(); if (extras != null && extras.containsKey(AppWidgetManager.EXTRA_APPWIDGET_ID) && extras.containsKey(AppWidgetManager.EXTRA_APPWIDGET_OPTIONS)) { int appWidgetId = extras.getInt(AppWidgetManager.EXTRA_APPWIDGET_ID); Bundle widgetExtras = extras.getBundle(AppWidgetManager.EXTRA_APPWIDGET_OPTIONS); this.onAppWidgetOptionsChanged(context, AppWidgetManager.getInstance(context), appWidgetId, widgetExtras); } } else if (AppWidgetManager.ACTION_APPWIDGET_ENABLED.equals(action)) { this.onEnabled(context); } else if (AppWidgetManager.ACTION_APPWIDGET_DISABLED.equals(action)) { this.onDisabled(context); } else if (AppWidgetManager.ACTION_APPWIDGET_RESTORED.equals(action)) { Bundle extras = intent.getExtras(); if (extras != null) { int[] oldIds = extras.getIntArray(AppWidgetManager.EXTRA_APPWIDGET_OLD_IDS); int[] newIds = extras.getIntArray(AppWidgetManager.EXTRA_APPWIDGET_IDS); if (oldIds != null && oldIds.length > 0) { this.onRestored(context, oldIds, newIds); this.onUpdate(context, AppWidgetManager.getInstance(context), newIds); } } } }