android 中 AppWidget 的 ListView 的实现
3.0 以后系统直接支持了ListView. 关于ListView 的国内资料匮乏,大多数例子都是转来转去。由于初学android, 鄙人在搜索资料的时候遇到了不少麻烦~很是郁闷和苦恼~深感国内学习氛围确实怪异，学习方式需要改变。应该多去查看官方文档。。。。
话不多说，现在开始listView 实现：
这是文档列出的支持的布局和widget控件：
A RemoteViews object (and, consequently, an App Widget) can support the following layout classes:
And the following widget classes:
- AnalogClock
- Button
- Chronometer
- ImageButton
- ImageView
- ProgressBar
- TextView
- ViewFlipper
- ListView
- GridView
- StackView
- AdapterViewFlipper
Descendants of these classes are not supported
其中有ListView和 GridView 等控件。
android 中实现 appWidget 有自己的一套机制：
1. widget 的支持，AppWidgetProvider 类的实现。
覆盖在 AppWidgetProvider 的 OnReceive() 函数，从android的源码中可以知道，AppWidgetProvider 的 OnUpdate() ， OnEnable(), OnDelete() 等方法都是从 OnReceive() 方法中分配进去的。即所有的广播先通过OnReceive()函数，再分配到OnUpdate()等函数去。
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_ENABLED.equals(action)) { this.onEnabled(context); } else if (AppWidgetManager.ACTION_APPWIDGET_DISABLED.equals(action)) { this.onDisabled(context); }}// END_INCLUDE(onReceive) |
注意到：
String action = intent.getAction(); |
这里 intent 先获取 action, 通过action 来获取到广播并区分类型，所以自己定义 action 通过 PendingIntent 来实现各种跳转~
到这里先摆下基础的文件吧：
这里需要注意到的是：android中的xml 文件不能有大写字母。区分单词用最好用 _ 符号。否则找不到文件名。
provider_info 文件，提供 appWidget 的一些基本控制信息。
<?xml version="1.0" encoding="utf-8"?><appwidget-provider android:minWidth = "294dp" android:minHeight = "367dp" android:updatePeriodMillis = "1000" android:initialLayout = "@layout/listview" android:background="#0000ff" > </appwidget-provider> |
listview 文件： ListView 控件就在内部：
<?xml version="1.0" encoding="utf-8"?><RelativeLayout android:layout_width="294dp" android:layout_height="400dp"> <LinearLayout android:layout_width="fill_parent" android:layout_height="360dp" android:minHeight="100dp" android:id="@+id/listviewWrapper" > <ListView android:layout_height = "360dp" android:layout_width = "294dp" android:background="#000000" android:id = "@+id/myListView" /> </LinearLayout> <Button android:layout_width="fill_parent" android:layout_height="wrap_content" android:layout_below="@id/listviewWrapper" android:layout_alignParentLeft="true" android:id="@+id/refresh" android:text="refresh" > </Button></RelativeLayout> |
下面是list_item 文件：
<?xml version="1.0" encoding="utf-8"?><RelativeLayout android:layout_width="match_parent" android:layout_height="match_parent"> <TextView android:layout_width="fill_parent" android:layout_height="wrap_content" android:gravity="center" android:textColor="#ff0000" android:layout_marginTop="5px" android:layout_marginBottom="5px" android:paddingBottom="25px" android:paddingTop="5px" android:textSize="60px" android:id="@+id/item" /> <ImageView android:id="@+id/imageItem" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_alignParentRight="true" android:layout_alignRight="@id/item" /></RelativeLayout> |
list 的 item 中也可以添加 ImageView 等appWidget 支持的控件。
这是manifest 问件：
<?xml version="1.0" encoding="utf-8"?><manifest xmlns:android="http://schemas.android.com/apk/res/android" package="com.zgc.AppWidget6" android:versionCode="1" android:versionName="1.0" > <uses-sdk android:minSdkVersion="15" /> <application android:icon="@drawable/ic_launcher" android:label="@string/app_name" > <receiver android:name=".MyWidgetProvider"> <meta-data android:name="android.appwidget.provider" android:resource="@xml/provider_info" > </meta-data> <intent-filter > <action android:name="android.appwidget.action.APPWIDGET_UPDATE"></action> </intent-filter> </receiver> <service android:name=".MyWidgetService" android:permission="android.permission.BIND_REMOTEVIEWS" android:exported="false" ></service> </application> <uses-permission android:name="android.permission.INTERNET"></uses-permission></manifest> |
其中 service 提供 name 是 MyWidgetService ，他是继承RemoteViewsService 类。是我们需要为 远程 ListView 提供 数据源的服务。
RemoteViewsService的是个服务。其中：
public RemoteViewsFactory onGetViewFactory(Intent intent) { return new ListRemoteViewsFactory(this.getApplicationContext(), intent); } |
ListRemoteViewsFactory 这里就充当 ListView 的数据源。 |
就好比在activity 中使用ListView 一样。也需要通过AdapterView 来为ListView 提供数据源。不过AdatperView中提供了每一Item的方法。
具体逻辑如图：
下面是 service 的源代码：
public class MyWidgetService extends RemoteViewsService { @Override public RemoteViewsFactory onGetViewFactory(Intent intent) { return new ListRemoteViewsFactory(this.getApplicationContext(), intent); } @Override public void onCreate() { // TODO Auto-generated method stub System.out.println("service in onCreate"); super.onCreate(); } @Override public void onDestroy() { // TODO Auto-generated method stub System.out.println("service in onDestory"); super.onDestroy(); } @Override public boolean onUnbind(Intent intent) { // TODO Auto-generated method stub System.out.println("service in onUnbind"); return super.onUnbind(intent); } @Override public void onRebind(Intent intent) { // TODO Auto-generated method stub System.out.println("service in onRebind"); super.onRebind(intent); } @Override public void onStart(Intent intent, int startId) { // TODO Auto-generated method stub System.out.println("service in onStart"); super.onStart(intent, startId); } @Override public int onStartCommand(Intent intent, int flags, int startId) { // TODO Auto-generated method stub return super.onStartCommand(intent, flags, startId); }}<br><br> |
class ListRemoteViewsFactory implements RemoteViewsService.RemoteViewsFactory { private static int mCount = 0; private List<WidgetItem> mWidgetItems = new ArrayList<WidgetItem>(); private List<String> mWidgetItemsAttr= new ArrayList<String>(); private Context mContext; private int mAppWidgetId; public static int whichPage = 0; public static int mainPageId = -1; public static int secPageId = -1; public static final int mainPage = 0; public static final int secPage = 1; public static List<Integer> checkPos = new ArrayList<Integer>(); //public static int[] checkPosArr = new int[100]; public ListRemoteViewsFactory(Context context, Intent intent){ mContext = context; mAppWidgetId = intent.getIntExtra(AppWidgetManager.EXTRA_APPWIDGET_ID, AppWidgetManager.INVALID_APPWIDGET_ID); } @Override public void onCreate() { System.out.println("onCreate in factory"); // TODO Auto-generated method stub try { Thread.sleep(3000); } catch (InterruptedException e) { e.printStackTrace(); } } @Override public int getCount() { // TODO Auto-generated method stub if(whichPage == mainPage){ mCount = mWidgetItems.size(); } else if(whichPage == secPage){ mCount = mWidgetItemsAttr.size(); } return mCount; } @Override public long getItemId(int position) { // TODO Auto-generated method stub return position; } @Override public RemoteViews getLoadingView() { // TODO Auto-generated method stub System.out.println("getLoadingView"); return null; } @Override public RemoteViews getViewAt(int position) { System.out.println("getViewAt"); // TODO Auto-generated method stub RemoteViews rv = new RemoteViews(mContext.getPackageName(), R.layout.list_item); switch(whichPage){ case mainPage : if(-1 == mainPageId){ //refresh main page System.out.println("getViewAt mainPage refresh"); rv.setTextViewText(R.id.item, mWidgetItems.get(position).text); Bundle extras = new Bundle(); extras.putInt("page", 0); extras.putInt(MyWidgetProvider.EXTRA_ITEM, position); extras.putString("name", mWidgetItems.get(position).text); Intent fillInIntent = new Intent(); fillInIntent.putExtras(extras); rv.setOnClickFillInIntent(R.id.item, fillInIntent); } else{ //refresh to secPage list content System.out.println("getViewAt mainPage item click"); mainPageId = -1; } break; case secPage: if(-1 == secPageId){ //refresh when click back button, but I only have one home button //refresh second list page System.out.println("getViewAt secPage refresh"); rv.setTextViewText(R.id.item, mWidgetItemsAttr.get(position)); rv.setImageViewResource(R.id.imageItem, R.drawable.checkbox); Bundle extras = new Bundle(); extras.putInt("page", 1); extras.putInt(MyWidgetProvider.EXTRA_ITEM, position); Intent fillInIntent = new Intent(); fillInIntent.putExtras(extras); rv.setOnClickFillInIntent(R.id.item, fillInIntent); rv.setOnClickFillInIntent(R.id.imageItem, fillInIntent); } else{ //change positon rv.setTextViewText(R.id.item, mWidgetItemsAttr.get(position)); if(-1 != checkPos.indexOf(position)){ //change list item picture to be checked rv.setImageViewResource(R.id.imageItem, R.drawable.checkedbox); } else{ rv.setImageViewResource(R.id.imageItem, R.drawable.checkbox); } //每一个 item 都需要从新赋值。否则会出错！！具体原因没有查明 Bundle extras = new Bundle(); extras.putInt("page", 1); extras.putInt(MyWidgetProvider.EXTRA_ITEM, position); Intent fillInIntent = new Intent(); fillInIntent.putExtras(extras); rv.setOnClickFillInIntent(R.id.item, fillInIntent); rv.setOnClickFillInIntent(R.id.imageItem, fillInIntent); } break; default: ; } return rv; } @Override public int getViewTypeCount() { // TODO Auto-generated method stub return 1; } @Override public boolean hasStableIds() { // TODO Auto-generated method stub return true; } @Override public void onDataSetChanged() { // TODO Auto-generated method stub System.out.println("onDataSetChanged"); //this func is get data mWidgetItems.clear(); switch(whichPage){ case mainPage : System.out.println("onDataSetChanged_mainPage"); if(-1 == mainPageId){ //refresh main page try{ URL reqURL = new URL(url); BufferedReader br = new BufferedReader(new InputStreamReader(reqURL.openStream(), "gbk")); StringBuffer sb = new StringBuffer(); String line; while(null != (line = br.readLine())){ sb.append(line); } br.close(); ArrayList <Map<String, Object>> mList= new ArrayList<Map<String, Object>>(); JSONArray arr_json = new JSONArray(sb.toString()); for(int i = 0, len = arr_json.length(); i < len; i++){ String strName = arr_json.getJSONObject(i).getString("name"); String strUrl = arr_json.getJSONObject(i).getString("url"); int id = arr_json.getJSONObject(i).getInt("id"); Map<String, Object> map = new HashMap<String, Object>(); mWidgetItems.add(new WidgetItem(strName, id)); map.put("name", strName); map.put("url", strUrl); mList.add(map); } mCount = mWidgetItems.size(); }catch(Exception e){ Toast.makeText(mContext, "can't connect server", Toast.LENGTH_LONG).show(); } } else{ // System.out.println("onDataSetChanged_mainPage else"); WidgetItem item = mWidgetItems.get(mainPageId); } System.out.println("onDataSetChanged_-1"); break; case secPage: //here can get more info from server, but no need to get more infomation, if(-1 == secPageId){ mWidgetItemsAttr.clear(); System.out.println("onDataSetChanged_secPage -1"); mWidgetItemsAttr.add("zhang"); mWidgetItemsAttr.add("gui"); mWidgetItemsAttr.add("chuang"); mWidgetItemsAttr.add("hui"); mWidgetItemsAttr.add("cong"); mWidgetItemsAttr.add("gui"); mWidgetItemsAttr.add("chuang"); mWidgetItemsAttr.add("hui"); mWidgetItemsAttr.add("cong"); mWidgetItemsAttr.add("gui"); mWidgetItemsAttr.add("chuang"); mWidgetItemsAttr.add("hui"); mWidgetItemsAttr.add("cong"); mWidgetItemsAttr.add("cong"); } else{ System.out.println("onDataSetChanged_secPage else"); } break; default: return ; } } @Override public void onDestroy() { System.out.println("onDestory in factory"); // TODO Auto-generated method stub mWidgetItems.clear(); }} |
<br> |
<br>注意到几个方法：<br>public void onDataSetChanged(){.....}<br>public RemoteViews getViewAt(int position) {....}<br>public int getCount() {....}<br><br>onDateSetChanged(){...} 方法在你使用的 MyWidgetProvider 的 onReceive() 和 onUpdate() 方法中调用 |
AppWidgetManager 的实例的方法: mgr.notifyAppWidgetViewDataChanged(appIds, R.id.myListView); 来更新要求更新数据源：<br>首先就会调用 ： |
onDataSetChanged(){.....} |
然后在调用 getViewAt(int position){....}<br>其中getViewAt 的参数 position 就是你的ListView中每一项 item 的位置。从 0 计数。<br>其中你必须 override 的 getCount()方法是返回你的ListView item 的总数。这个自己必须返回自己的数据才能让getViewAt的postion能够计数。<br><br>你获取数据的方式比如http从服务器获取数据的话，就需要放在onDateSetChagged()方法里。<br>当然 public RemoteViews getLoadingView(){...} 也可以。不过要注意放回的是RemoteViews 就说明这是要更新界面的，这个函数的作用就是在你更新界面的时候如果耗时就会显示 正在加载... 的默认字样，但是你可以更改这个界面。需要返回一个 RemoteViews 类型。其中你可以使用RemoteViews 去切换自己定义的 Layout 。<br><br>关于 remoteViews 的实例的方法： |
rv.setOnClickFillInIntent(R.id.item, fillInIntent); |
在下面会解释。<br><br><br>下面是provider: |
public class MyWidgetProvider extends AppWidgetProvider{ public static final String TOAST_ACTION = "com.zgc.listwidget.TOAST_ACTION"; public static final String EXTRA_ITEM = "com.zgc.listwidget.EXTRA_ITEM"; public static final String TO_SITE = "com.zgc.listwidget.TO_SITE"; public static final String SITE = "com.zgc.listwidget.SITE"; public static final String BACK_HOME = "com.zgc.listwidget.BACK_HOME"; public static String PicName = ""; public static final String REFRESH = "com.zgc.listwidget.REFRESH"; public static final String ITEM = "com.zgc.AppWidget6.ITEM"; @Override public IBinder peekService(Context myContext, Intent service) { // TODO Auto-generated method stub System.out.println("peekService in provider"); return super.peekService(myContext, service); } @Override public void onDeleted(Context context, int[] appWidgetIds) { // TODO Auto-generated method stub System.out.println("onDeleted in Provider"); super.onDeleted(context, appWidgetIds); } @Override public void onDisabled(Context context) { // TODO Auto-generated method stub System.out.println("onDisabled in Provider"); super.onDisabled(context); } @Override public void onEnabled(Context context) { // TODO Auto-generated method stub System.out.println("onEnabled in Provider"); super.onEnabled(context); } @Override public void onReceive(Context context, Intent intent) { // TODO Auto-generated method stub AppWidgetManager mgr = AppWidgetManager.getInstance(context); ComponentName cmpName = new ComponentName(context, MyWidgetProvider.class); if (intent.getAction().equals(ITEM)) { System.out.println("item action"); int pageNum = intent.getIntExtra("page", 1); int itemPos = intent.getIntExtra(EXTRA_ITEM, 0); if(0 == pageNum){ System.out.println("item action 0 page"); ListRemoteViewsFactory.secPageId = -1; ListRemoteViewsFactory.whichPage = ListRemoteViewsFactory.secPage; int[] appIds = mgr.getAppWidgetIds(cmpName); mgr.notifyAppWidgetViewDataChanged(appIds, R.id.myListView); //change refresh to commit button ,here no need to reload listview RemoteViews rv2 = new RemoteViews(context.getPackageName(), R.layout.listview); rv2.setTextViewText(R.id.refresh, "commit"); Intent commitIntent = new Intent(context, MyWidgetProvider.class); commitIntent.setData(Uri.parse(commitIntent.toUri(Intent.URI_INTENT_SCHEME))); commitIntent.setAction(SITE); PendingIntent commitPendingIntent = PendingIntent.getBroadcast(context, 0, commitIntent, PendingIntent.FLAG_UPDATE_CURRENT); rv2.setOnClickPendingIntent(R.id.refresh, commitPendingIntent); mgr.updateAppWidget(appIds, rv2); } else if(1 == pageNum){ System.out.println("item action 1 page"); ListRemoteViewsFactory.secPageId = itemPos; if(-1 == ListRemoteViewsFactory.checkPos.indexOf(itemPos)){ ListRemoteViewsFactory.checkPos.add(itemPos); } else{ ListRemoteViewsFactory.checkPos.remove(ListRemoteViewsFactory.checkPos.indexOf(itemPos)); } int[] appIds = mgr.getAppWidgetIds(cmpName); mgr.notifyAppWidgetViewDataChanged(appIds, R.id.myListView); } } else if(intent.getAction().equals(SITE)){ System.out.println("in receive commit SITE action"); RemoteViews rv = new RemoteViews(context.getPackageName(), R.layout.img); int id = R.drawable.uliuli; if(PicName.equals("google")){ id = R.drawable.uliuli; } else if(PicName.equals("douban")){ id = R.drawable.uliuli; } rv.setImageViewResource(R.id.displayImage, id); Intent homeIntent = new Intent(context, MyWidgetProvider.class); homeIntent.setAction(BACK_HOME); //homeIntent.setAction(AppWidgetManager.ACTION_APPWIDGET_UPDATE); homeIntent.setData(Uri.parse(homeIntent.toUri(Intent.URI_INTENT_SCHEME))); PendingIntent pendingIntent = PendingIntent.getBroadcast(context, 0, homeIntent, PendingIntent.FLAG_UPDATE_CURRENT); rv.setOnClickPendingIntent(R.id.backHome, pendingIntent); mgr.updateAppWidget(cmpName, rv); //Toast.makeText(context, "Touched view zhang", Toast.LENGTH_SHORT).show(); } else if(intent.getAction().equals(BACK_HOME)){ System.out.println("back_home "); int[] appWidgetIds = mgr.getAppWidgetIds(cmpName); //mgr.notifyAppWidgetViewDataChanged(appWidgetIds, R.id.myListView); Intent serviceIntent = new Intent(context, MyWidgetService.class); // //intent.putExtra(AppWidgetManager.EXTRA_APPWIDGET_ID, appWidgetIds[i]); serviceIntent.setData(Uri.parse(serviceIntent.toUri(Intent.URI_INTENT_SCHEME))); RemoteViews rv = new RemoteViews(context.getPackageName(), R.layout.listview); rv.setRemoteAdapter(R.id.myListView, serviceIntent); Intent toastIntent = new Intent(context, MyWidgetProvider.class); toastIntent.setAction(MyWidgetProvider.ITEM); intent.setData(Uri.parse(intent.toUri(Intent.URI_INTENT_SCHEME))); PendingIntent toastPendingIntent = PendingIntent.getBroadcast(context, 0, toastIntent, PendingIntent.FLAG_UPDATE_CURRENT); rv.setPendingIntentTemplate(R.id.myListView, toastPendingIntent); mgr.updateAppWidget(appWidgetIds, rv); Intent refreshIntent = new Intent(context, MyWidgetProvider.class); refreshIntent.setAction(REFRESH); PendingIntent refreshPendingIntent = PendingIntent.getBroadcast(context, 0, refreshIntent, 0); rv.setOnClickPendingIntent(R.id.refresh, refreshPendingIntent); ListRemoteViewsFactory.whichPage = ListRemoteViewsFactory.mainPage; ListRemoteViewsFactory.mainPageId = -1; mgr.updateAppWidget(cmpName, rv); mgr.notifyAppWidgetViewDataChanged(appWidgetIds, R.id.myListView); System.out.println("zhanggui"); //Toast.makeText(context, "Touched view back home", Toast.LENGTH_SHORT).show(); } else if(intent.getAction().equals(REFRESH)){ System.out.println("refresh button begin"); int[] appWidgetIds = mgr.getAppWidgetIds(cmpName); mgr.notifyAppWidgetViewDataChanged(appWidgetIds, R.id.myListView); System.out.println("refresh button end"); } super.onReceive(context, intent); } @Override public void onUpdate(Context context, AppWidgetManager appWidgetManager, int[] appWidgetIds) { System.out.println("onUpdate"); // TODO Auto-generated method stub for(int i = 0; i < appWidgetIds.length; i++){ Intent intent = new Intent(context, MyWidgetService.class); intent.putExtra(AppWidgetManager.EXTRA_APPWIDGET_ID, appWidgetIds[i]); // When intents are compared, the extras are ignored, so we need to embed the extras // into the data so that the extras will not be ignored. intent.setData(Uri.parse(intent.toUri(Intent.URI_INTENT_SCHEME))); RemoteViews rv = new RemoteViews(context.getPackageName(), R.layout.listview); rv.setRemoteAdapter(R.id.myListView, intent); //rv.setEmptyView(R.id.myListView, R.id.empty); Intent refreshIntent = new Intent(context, MyWidgetProvider.class); refreshIntent.setAction(REFRESH); PendingIntent refreshPendingIntent = PendingIntent.getBroadcast(context, 0, refreshIntent, 0); rv.setOnClickPendingIntent(R.id.refresh, refreshPendingIntent); Intent toastIntent = new Intent(context, MyWidgetProvider.class); toastIntent.setAction(MyWidgetProvider.ITEM); //toastIntent.putExtra("page", 0); // main page intent.setData(Uri.parse(intent.toUri(Intent.URI_INTENT_SCHEME))); PendingIntent toastPendingIntent = PendingIntent.getBroadcast(context, 0, toastIntent, PendingIntent.FLAG_UPDATE_CURRENT); rv.setPendingIntentTemplate(R.id.myListView, toastPendingIntent); appWidgetManager.updateAppWidget(appWidgetIds[i], rv); } super.onUpdate(context, appWidgetManager, appWidgetIds); }} |
首先看onUpdate() 函数，默认是从这里先进去的：
申明intent 后使用：
intent.setData(Uri.parse(intent.toUri(Intent.URI_INTENT_SCHEME))); |
用：这是为了让 intent 能够带上 extras 数据一起传递，否则在intent的比较的过程中会被忽略掉。这里的比较应该是在同一个代码块中有多个intent的时候会发生比较吧（猜测：因为当一条逻辑执行路径上代码块中只有一个Intent发送的时候能够带数据(不适用intent.setData函数)，但是有多个Intent的话不行）
PendingIntent 的使用不再解释。不过这里的 remoteView 实例使用：
rv.setPendingIntentTemplate(R.id.myListView, toastPendingIntent); |
listView 使用 setPendingIntentTemplate 方法，当你点击 ListView 中的任何一个item 时都会发送 toastPendingIntent ，在我们的 service 中的getViewAt() 方法中，为每一个item 都设置了一个 intent ：
rv.setOnClickFillInIntent(R.id.item, fillInIntent); |
其中 remoteViews 的setOnClickFillInIntent() 是将 fillIntent 合并到 toastPendingIntent 中去。就是两个 intent 合并了。
具体的合并方法是Intent中的fillIn(..) 方法：
Intent A ： {data="foo", categories="bar"}
Intent B ： {action="gotit", data-type="some/thing", categories="one","two"}.
调用 fillIn()： A.fillIn(B, Intent.FILL_IN_DATA)
结果： A : {action="gotit", data-type="some/thing", categories="bar"}.
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注意到 action 还是你在 onUpdate()中设置的 action,当然你也可以在 item 中的 fillInIntent 设置action.但是不好。
这里可以在每个 item 的 fillInIntent 中 使用 putExtras() 方法让Intent 带每个item 的 位置号码 来区分每个 item.
机制基本上已经说完，还有一点就是：
RemoteViewsService 中每次获取数据都会重新创建 service 和 销毁 service ，但是 RemoteViewsService.RemoteViewsFactory
的销毁则是在 机器上把 appWidget 删除后发生。就好像 RemoteViewsService.RemoteViewsFactory 是个数据库。你每次去访问这个数据源都会创建 一个 RemoteViewsService 然后销毁。这个源于我android学习1月，也不清楚内部机制。没仔细研究。等研究了再发文表上。
还有 AppWidgetProvider 类的实例是每发送一次 intent （即每一次 boardcast） 就新建一次，所以如果需要做 flag 来表示按钮是否check的话，最好就先声明为 static 类型或者放到其他类中。
其余的就是自己逻辑的实现：
我这里实现了 两个 ListView 的数据加载(通过http从服务器获取数据)和点入每条item进入另外的页面(这里也是在listView上从新加载数据，但是可以区分每个Item。也可以自己加载其他的layout)。还可以实现回到第一个加载的页面。其实可以做到回到上一个页面。
原文：http://www.cnblogs.com/debugman/archive/2012/06/18/android.html
