HoneyComb3.0技术系列之AppWidget(RemoteViewService)

浏览数：45 / 时间：2015年06月11日

1. 概述：

在HoneyComb3.0中AppWidget上可以添加更多的组件，如：ListView，GridView，StackView和ViewFlipper等集合组件。它提供了一套新的

集合组件渲染机制RemoteViewService，它继承自Service,向外提供渲染ListView，GridView或StackView等集合组件的Factory，这个Factory

类似Adapter向这些集合组件提供数据。在AppWidgetProviderInfo类中（<appwidget-provider>标签）新增加了两个属性，一个是

previewImage，这个属性指定一张图片，这个图片显示在添加AppWidget的Picker界面中，拖动这张图片到Launcher的WorkSpace后就向其中

添加图片所对应的AppWidget，另一个是autoAdvanceViewId，这个属性指定自动更新的ViewID，我指定StackView的ID有效果（View之间不

停的滑动），但是指定的ListView或GridView的ID没有任何效果。

2. 整体效果图：

（1）AppWidget的Picker效果图，如下：

（2）AppWidget效果图，如下：

3. AppWidget的代码实现，如下：

（1）AndroidManifest.xml配置文件，如下：

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<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.android.weatherlistwidget">
<application android:label="Weather Widget Sample">
<receiver android:name="WeatherWidgetProvider">
<intent-filter>
<action android:name="android.appwidget.action.APPWIDGET_UPDATE" />
</intent-filter>
<meta-data android:name="android.appwidget.provider"
android:resource="@xml/widgetinfo" />
</receiver>
<service android:name="WeatherWidgetService"
android:permission="android.permission.BIND_REMOTEVIEWS"
android:exported="false" />
<provider android:name="WeatherDataProvider"
android:authorities="com.example.android.weatherlistwidget.provider" />
</application>
<uses-sdk android:minSdkVersion="11" />
</manifest>

（2）res/xml/目录中AppWidget的配置文件，如下：

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<?xml version="1.0" encoding="utf-8"?>
<appwidget-provider
xmlns:android="http://schemas.android.com/apk/res/android"
android:minWidth="222dip"
android:minHeight="222dip"
android:updatePeriodMillis="1800000"
android:initialLayout="@layout/widget_layout"
android:previewImage="@drawable/preview"
>
</appwidget-provider>

（3）res/layout目录中AppWidget的总布局，如下：

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<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="294dp"
android:layout_height="match_parent"
android:orientation="vertical">
<FrameLayout
android:layout_width="match_parent"
android:layout_height="wrap_content">
<ImageView
android:id="@+id/header"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:src="@drawable/header" />
<ImageButton
android:id="@+id/refresh"
android:layout_width="56dp"
android:layout_height="39dp"
android:layout_marginLeft="222dp"
android:layout_marginTop="20dp"
android:background="@drawable/refresh_button" />
</FrameLayout>
<FrameLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_weight="1"
android:layout_gravity="center"
android:background="@drawable/body">
<ListView
android:id="@+id/weather_list"
android:layout_width="match_parent"
android:layout_height="match_parent" />
<TextView
android:id="@+id/empty_view"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:gravity="center"
android:visibility="gone"
android:textColor="#ffffff"
android:text="@string/empty_view_text"
android:textSize="20sp" />
</FrameLayout>
<ImageView
android:id="@+id/footer"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:src="@drawable/footer" />
</LinearLayout>

（4）ContentProvider类，如下：

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package com.example.android.weatherlistwidget;
import java.util.ArrayList;
import android.content.ContentProvider;
import android.content.ContentValues;
import android.database.Cursor;
import android.database.MatrixCursor;
import android.net.Uri;
class WeatherDataPoint {
String city;
int degrees;
WeatherDataPoint(String c, int d) {
city = c;
degrees = d;
}
}
public class WeatherDataProvider extends ContentProvider {
public static final Uri CONTENT_URI = Uri.parse("content://com.example.android.weatherlistwidget.provider");
public static class Columns {
public static final String ID = "_id";
public static final String CITY = "city";
public static final String TEMPERATURE = "temperature";
}
private static final ArrayList<WeatherDataPoint> sData = new ArrayList<WeatherDataPoint>();
/**
* 在onCreate()时初始化数据。
*/
@Override
public boolean onCreate() {
sData.add(new WeatherDataPoint("San Francisco", 13));
sData.add(new WeatherDataPoint("New York", 1));
sData.add(new WeatherDataPoint("Seattle", 7));
sData.add(new WeatherDataPoint("Boston", 4));
sData.add(new WeatherDataPoint("Miami", 22));
sData.add(new WeatherDataPoint("Toronto", -10));
sData.add(new WeatherDataPoint("Calgary", -13));
sData.add(new WeatherDataPoint("Tokyo", 8));
sData.add(new WeatherDataPoint("Kyoto", 11));
sData.add(new WeatherDataPoint("London", -1));
sData.add(new WeatherDataPoint("Nomanisan", 27));
return true;
}
@Override
public synchronized Cursor query(Uri uri, String[] projection, String selection,
String[] selectionArgs, String sortOrder) {
assert(uri.getPathSegments().isEmpty());
/**
* 创建MatrixCursor，并向MatrixCursor中添加数据，返回。
*/
final MatrixCursor c = new MatrixCursor(new String[]{ Columns.ID, Columns.CITY, Columns.TEMPERATURE });
for (int i = 0; i < sData.size(); ++i) {
final WeatherDataPoint data = sData.get(i);
c.addRow(new Object[]{ new Integer(i), data.city, new Integer(data.degrees) });
}
return c;
}
@Override
public String getType(Uri uri) {
return "vnd.android.cursor.dir/vnd.weatherlistwidget.citytemperature";
}
@Override
public Uri insert(Uri uri, ContentValues values) {
return null;
}
@Override
public int delete(Uri uri, String selection, String[] selectionArgs) {
return 0;
}
@Override
public synchronized int update(Uri uri, ContentValues values, String selection, String[] selectionArgs) {
assert(uri.getPathSegments().size() == 1);
final int index = Integer.parseInt(uri.getPathSegments().get(0));
assert(0 <= index && index < sData.size());
final WeatherDataPoint data = sData.get(index);
data.degrees = values.getAsInteger(Columns.TEMPERATURE);
/**
* 提醒ContentObserver数据改变。
*/
getContext().getContentResolver().notifyChange(uri, null);
return 1;
}
}

（5）AppWidget类，如下：

[java] view plain copy

package com.example.android.weatherlistwidget;
import java.util.Random;
import android.app.PendingIntent;
import android.appwidget.AppWidgetManager;
import android.appwidget.AppWidgetProvider;
import android.content.ComponentName;
import android.content.ContentResolver;
import android.content.ContentUris;
import android.content.ContentValues;
import android.content.Context;
import android.content.Intent;
import android.database.ContentObserver;
import android.database.Cursor;
import android.net.Uri;
import android.os.Handler;
import android.os.HandlerThread;
import android.widget.RemoteViews;
import android.widget.Toast;
class WeatherDataProviderObserver extends ContentObserver {
private AppWidgetManager mAppWidgetManager;
private ComponentName mComponentName;
WeatherDataProviderObserver(AppWidgetManager mgr, ComponentName cn, Handler h) {
super(h);
mAppWidgetManager = mgr;
mComponentName = cn;
}
/**
* ContentProvider的内容改变后会通过AppWidget组件中的ListView重新渲染数据。这里会调用RemoteViewService中RemoteViewsFactory的onDataSetChanged方法。
*/
@Override
public void onChange(boolean selfChange) {
mAppWidgetManager.notifyAppWidgetViewDataChanged(mAppWidgetManager.getAppWidgetIds(mComponentName), R.id.weather_list);
}
}
public class WeatherWidgetProvider extends AppWidgetProvider {
public static String CLICK_ACTION = "com.example.android.weatherlistwidget.CLICK";
public static String REFRESH_ACTION = "com.example.android.weatherlistwidget.REFRESH";
public static String EXTRA_CITY_ID = "com.example.android.weatherlistwidget.city";
private static HandlerThread sWorkerThread;
private static Handler sWorkerQueue;
private static WeatherDataProviderObserver sDataObserver;
public WeatherWidgetProvider() {
sWorkerThread = new HandlerThread("WeatherWidgetProvider-worker");
sWorkerThread.start();
sWorkerQueue = new Handler(sWorkerThread.getLooper());
}
@Override
public void onEnabled(Context context) {
final ContentResolver r = context.getContentResolver();
/**
* 在发出AppWidget的Enable广播后向WeatherDataProvider注册WeatherDataProviderObserver（ContentObserver）。
*/
if (sDataObserver == null) {
final AppWidgetManager mgr = AppWidgetManager.getInstance(context);
final ComponentName cn = new ComponentName(context, WeatherWidgetProvider.class);
sDataObserver = new WeatherDataProviderObserver(mgr, cn, sWorkerQueue);
r.registerContentObserver(WeatherDataProvider.CONTENT_URI, true, sDataObserver);
}
}
@Override
public void onReceive(Context ctx, Intent intent) {
final String action = intent.getAction();
if (action.equals(REFRESH_ACTION)) {
final Context context = ctx;
sWorkerQueue.removeMessages(0);
sWorkerQueue.post(new Runnable() {
/**
* 单击刷新按钮后会更新数据。
*/
@Override
public void run() {
final ContentResolver r = context.getContentResolver();
final Cursor c = r.query(WeatherDataProvider.CONTENT_URI, null, null, null,
null);
final int count = c.getCount();
final int maxDegrees = 96;
r.unregisterContentObserver(sDataObserver);
for (int i = 0; i < count; ++i) {
final Uri uri = ContentUris.withAppendedId(WeatherDataProvider.CONTENT_URI, i);
final ContentValues values = new ContentValues();
values.put(WeatherDataProvider.Columns.TEMPERATURE,
new Random().nextInt(maxDegrees));
r.update(uri, values, null, null);
}
r.registerContentObserver(WeatherDataProvider.CONTENT_URI, true, sDataObserver);
final AppWidgetManager mgr = AppWidgetManager.getInstance(context);
final ComponentName cn = new ComponentName(context, WeatherWidgetProvider.class);
/**
* 这句话会调用RemoteViewSerivce中RemoteViewsFactory的onDataSetChanged()方法。
*/
mgr.notifyAppWidgetViewDataChanged(mgr.getAppWidgetIds(cn), R.id.weather_list);
}
});
} else if (action.equals(CLICK_ACTION)) {
/**
* 单击ListView中的某一项会显示一个Toast提示。
*/
final String city = intent.getStringExtra(EXTRA_CITY_ID);
final String formatStr = ctx.getResources().getString(R.string.toast_format_string);
Toast.makeText(ctx, String.format(formatStr, city), Toast.LENGTH_SHORT).show();
}
super.onReceive(ctx, intent);
}
@Override
public void onUpdate(Context context, AppWidgetManager appWidgetManager, int[] appWidgetIds) {
for (int i = 0; i < appWidgetIds.length; ++i) {
/**
* 创建请求Service的Intent对象。
*/
final Intent intent = new Intent(context, WeatherWidgetService.class);
intent.putExtra(AppWidgetManager.EXTRA_APPWIDGET_ID, appWidgetIds[i]);
intent.setData(Uri.parse(intent.toUri(Intent.URI_INTENT_SCHEME)));
/**
* 创建RemoteViews对象，在其中的布局中存在一个ListView组件widget_layout。
*/
final RemoteViews rv = new RemoteViews(context.getPackageName(), R.layout.widget_layout);
/**
* 组件ListView组件weather_list设置RemoteViewService渲染ListView.
*/
rv.setRemoteAdapter(appWidgetIds[i], R.id.weather_list, intent);
/**
* 如果weather_list为空则显示empty_view。
*/
rv.setEmptyView(R.id.weather_list, R.id.empty_view);
/**
* 点击ListView某一项时会显示一个Toast提示。
*/
final Intent onClickIntent = new Intent(context, WeatherWidgetProvider.class);
onClickIntent.setAction(WeatherWidgetProvider.CLICK_ACTION);
onClickIntent.putExtra(AppWidgetManager.EXTRA_APPWIDGET_ID, appWidgetIds[i]);
onClickIntent.setData(Uri.parse(onClickIntent.toUri(Intent.URI_INTENT_SCHEME)));
final PendingIntent onClickPendingIntent = PendingIntent.getBroadcast(context, 0,
onClickIntent, PendingIntent.FLAG_UPDATE_CURRENT);
rv.setPendingIntentTemplate(R.id.weather_list, onClickPendingIntent);
/**
* 点击刷新按钮时刷新ListView数据。
*/
final Intent refreshIntent = new Intent(context, WeatherWidgetProvider.class);
refreshIntent.setAction(WeatherWidgetProvider.REFRESH_ACTION);
final PendingIntent refreshPendingIntent = PendingIntent.getBroadcast(context, 0,
refreshIntent, PendingIntent.FLAG_UPDATE_CURRENT);
rv.setOnClickPendingIntent(R.id.refresh, refreshPendingIntent);
/**
* 更新AppWidget组件。
*/
appWidgetManager.updateAppWidget(appWidgetIds[i], rv);
}
super.onUpdate(context, appWidgetManager, appWidgetIds);
}
}

（6）RemoteViewsService渲染器，如下：

[java] view plain copy

package com.example.android.weatherlistwidget;
import android.content.Context;
import android.content.Intent;
import android.database.Cursor;
import android.os.Bundle;
import android.widget.RemoteViews;
import android.widget.RemoteViewsService;
public class WeatherWidgetService extends RemoteViewsService {
@Override
public RemoteViewsFactory onGetViewFactory(Intent intent) {
return new StackRemoteViewsFactory(this.getApplicationContext(), intent);
}
}
/**
* 这个Factory就类拟一个Adapter,可以为AppWidget中的集合组件设置数据。
*/
class StackRemoteViewsFactory implements RemoteViewsService.RemoteViewsFactory {
private Context mContext;
private Cursor mCursor;
public StackRemoteViewsFactory(Context context, Intent intent) {
mContext = context;
}
public void onCreate() {
}
public void onDestroy() {
if (mCursor != null) {
mCursor.close();
}
}
/**
* 获取Cursor中的数据个数。
*/
public int getCount() {
return mCursor.getCount();
}
/**
* 获取ListView中的每一个条目View.
*/
public RemoteViews getViewAt(int position) {
String city = "Unknown City";
int temp = 0;
if (mCursor.moveToPosition(position)) {
final int cityColIndex = mCursor.getColumnIndex(WeatherDataProvider.Columns.CITY);
final int tempColIndex = mCursor.getColumnIndex(
WeatherDataProvider.Columns.TEMPERATURE);
city = mCursor.getString(cityColIndex);
temp = mCursor.getInt(tempColIndex);
}
final String formatStr = mContext.getResources().getString(R.string.item_format_string);
final int itemId = (position % 2 == 0 ? R.layout.light_widget_item
: R.layout.dark_widget_item);
RemoteViews rv = new RemoteViews(mContext.getPackageName(), itemId);
rv.setTextViewText(R.id.widget_item, String.format(formatStr, temp, city));
final Intent fillInIntent = new Intent();
final Bundle extras = new Bundle();
extras.putString(WeatherWidgetProvider.EXTRA_CITY_ID, city);
fillInIntent.putExtras(extras);
rv.setOnClickFillInIntent(R.id.widget_item, fillInIntent);
return rv;
}
public RemoteViews getLoadingView() {
return null;
}
public int getViewTypeCount() {
return 2;
}
public long getItemId(int position) {
return position;
}
public boolean hasStableIds() {
return true;
}
/**
* 在AppWidget被第一次加载到屏幕时会自动调用此方法或者调用AppWidgetManager.notifyAppWidgetViewDataChanged()方法也会调用此方法。
*/
public void onDataSetChanged() {
if (mCursor != null) {
mCursor.close();
}
mCursor = mContext.getContentResolver().query(WeatherDataProvider.CONTENT_URI, null, null, null, null);
}
}