onDatasetChanged方法包含异步网络调用Android时Widget ListView不刷新
onDatasetChanged方法包含异步网络调用Android时Widget ListView不刷新
提问于 2018-07-29 21:51:26
我想加载一个汽车清单从互联网到一个小工具的ListView。当我在onDatasetChanged方法中请求汽车时，它不会更新列表。但是，当我手动单击刷新按钮时，它确实会刷新它。可能的问题是什么？为了提供尽可能多的信息，我放入了complete source into a ZIP file，它可以被解压并在Android Studio中打开。我也会把它嵌入到下面。注意:我正在使用RxJava处理异步请求，代码是用Kotlin编写的，尽管这个问题不是每种语言的限制。
CarsWidgetProvider
class CarsWidgetProvider : AppWidgetProvider() {
override fun onUpdate(context: Context, appWidgetManager: AppWidgetManager, appWidgetIds: IntArray) {
Log.d("CAR_LOG", "Updating")
val widgets = appWidgetIds.size
for (i in 0 until widgets) {
Log.d("CAR_LOG", "Updating number $i")
val appWidgetId = appWidgetIds[i]
// Get the layout
val views = RemoteViews(context.packageName, R.layout.widget_layout)
val otherIntent = Intent(context, ListViewWidgetService::class.java)
views.setRemoteAdapter(R.id.cars_list, otherIntent)
// Set an onclick listener for the action and the refresh button
views.setPendingIntentTemplate(R.id.cars_list, getPendingSelfIntent(context, "action"))
views.setOnClickPendingIntent(R.id.refresh, getPendingSelfIntent(context, "refresh"))
// Tell the AppWidgetManager to perform an update on the current app widget
appWidgetManager.updateAppWidget(appWidgetId, views)
}
}
private fun onUpdate(context: Context) {
val appWidgetManager = AppWidgetManager.getInstance(context)
val thisAppWidgetComponentName = ComponentName(context.packageName, javaClass.name)
val appWidgetIds = appWidgetManager.getAppWidgetIds(thisAppWidgetComponentName)
appWidgetManager.notifyAppWidgetViewDataChanged(appWidgetIds, R.id.cars_list)
onUpdate(context, appWidgetManager, appWidgetIds)
}
private fun getPendingSelfIntent(context: Context, action: String): PendingIntent {
val intent = Intent(context, javaClass)
intent.action = action
return PendingIntent.getBroadcast(context, 0, intent, 0)
}
@SuppressLint("CheckResult")
override fun onReceive(context: Context?, intent: Intent?) {
super.onReceive(context, intent)
if (context != null) {
if ("action" == intent!!.action) {
val car = intent.getSerializableExtra("car") as Car
// Toggle car state
Api.toggleCar(car)
.subscribeOn(Schedulers.io())
.observeOn(AndroidSchedulers.mainThread())
.subscribe {
Log.d("CAR_LOG", "We've got a new state: $it")
car.state = it
onUpdate(context)
}
} else if ("refresh" == intent.action) {
onUpdate(context)
}
}
}
}ListViewWidgetService
class ListViewWidgetService : RemoteViewsService() {
override fun onGetViewFactory(intent: Intent): RemoteViewsService.RemoteViewsFactory {
return ListViewRemoteViewsFactory(this.applicationContext, intent)
}
}
internal class ListViewRemoteViewsFactory(private val context: Context, intent: Intent) : RemoteViewsService.RemoteViewsFactory {
private var cars: ArrayList<Car> = ArrayList()
override fun onCreate() {
Log.d("CAR_LOG", "Oncreate")
cars = ArrayList()
}
override fun getViewAt(position: Int): RemoteViews {
val remoteViews = RemoteViews(context.packageName, R.layout.widget_list_item_car)
// Get the current car
val car = cars[position]
Log.d("CAR_LOG", "Get view at $position")
Log.d("CAR_LOG", "Car: $car")
// Fill the list item with data
remoteViews.setTextViewText(R.id.title, car.title)
remoteViews.setTextViewText(R.id.description, car.model)
remoteViews.setTextViewText(R.id.action, "${car.state}")
remoteViews.setInt(R.id.action, "setBackgroundColor",
if (car.state == 1) context.getColor(R.color.colorGreen) else context.getColor(R.color.colorRed))
val extras = Bundle()
extras.putSerializable("car", car)
val fillInIntent = Intent()
fillInIntent.putExtras(extras)
remoteViews.setOnClickFillInIntent(R.id.activity_chooser_view_content, fillInIntent)
return remoteViews
}
override fun getCount(): Int {
Log.d("CAR_LOG", "Counting")
return cars.size
}
@SuppressLint("CheckResult")
override fun onDataSetChanged() {
Log.d("CAR_LOG", "Data set changed")
// Get a token
Api.getToken()
.subscribeOn(Schedulers.io())
.observeOn(AndroidSchedulers.mainThread())
.subscribe { token ->
if (token.isNotEmpty()) {
Log.d("CAR_LOG", "Retrieved token")
DataModel.token = token
// Get the cars
Api.getCars()
.subscribeOn(Schedulers.io())
.observeOn(AndroidSchedulers.mainThread())
.subscribe {
cars = it as ArrayList<Car>
Log.d("CAR_LOG", "Found cars: $cars")
}
} else {
Api.getCars()
.subscribeOn(Schedulers.io())
.observeOn(AndroidSchedulers.mainThread())
.subscribe {
cars = it as ArrayList<Car>
Log.d("CAR_LOG", "Found cars: $cars")
}
}
}
}
override fun getViewTypeCount(): Int {
Log.d("CAR_LOG", "Get view type count")
return 1
}
override fun getItemId(position: Int): Long {
Log.d("CAR_LOG", "Get item ID")
return position.toLong()
}
override fun onDestroy() {
Log.d("CAR_LOG", "On Destroy")
cars.clear()
}
override fun hasStableIds(): Boolean {
Log.d("CAR_LOG", "Has stable IDs")
return true
}
override fun getLoadingView(): RemoteViews? {
Log.d("CAR_LOG", "Get loading view")
return null
}
}DataModel
object DataModel {
var token: String = ""
var currentCar: Car = Car()
var cars: ArrayList<Car> = ArrayList()
init {
Log.d("CAR_LOG", "Creating data model")
}
override fun toString(): String {
return "Token : $token \n currentCar: $currentCar \n Cars: $cars"
}
}小汽车
class Car : Serializable {
var id : String = ""
var title: String = ""
var model: String = ""
var state: Int = 0
}编辑
在我收到一些答案后，我开始找出一个临时修复方法，即在AsyncTask上调用.get()，这使它成为同步的
@SuppressLint("CheckResult")
override fun onDataSetChanged() {
cars = GetCars().execute().get() as ArrayList<Car>
}
class GetCars : AsyncTask<String, Void, List<Car>>() {
override fun doInBackground(vararg params: String?): List<Device> {
return Api.getCars().blockingFirst();
}
}回答 1
Stack Overflow用户
回答已采纳
发布于 2018-08-01 16:56:30
正如@ferini所说，你的rx链是一个异步调用，所以当你调用appWidgetManager.notifyAppWidgetViewDataChanged(appWidgetIds, R.id.cars_list)时到底发生了什么：
正如您所看到的，在调用notifyAppWidgetViewDataChanged() onDataSetChange()之后，但是您的调用是异步的，这就是为什么RemoteViewFactory会进一步使用FetchMetaData (查看图片)。因此，在小部件第一次启动时，您将cars初始化为ArrayList()，这就是ListView为空的原因。当您发送刷新操作时，您cars不是空的，因为您在onDataSetChange()中启动的异步调用已经获取数据并填充了您的cars，这就是为什么在刷新操作时通过最后一个异步调用填充ListView。
正如您所看到的，onDataSetChanged()用于填充数据库中的某些数据或类似的内容。您可以选择如何更新您的小部件：
- 通过在onDataSetChange中调用notifyAppWidgetViewDataChanged()，在数据库中保存和在IntentService ()中提取。使用RemoteView上的可打包数据和setRemoteAdapter()为listview适配器处理完全更新并创建新的intent，因此在onCreate RemoteViewsService中，将intent传递给RemoteViewsFactory，您可以从intent中获取汽车的数组列表，并将其设置为RemoteViewsFactory，在这种情况下，您根本不需要onDataSetChange()回调。
- 只是在onDataSetChange()中进行所有同步(阻塞)调用，因为它不是UI线程。
您可以通过在onDataSetChanged()中进行阻塞rx调用来轻松地检查这一点，您的小部件将按您所希望的那样工作。
override fun onDataSetChanged() {
Log.d("CAR_LOG", "Data set changed")
cars = Api.getCars().blockingFirst() as ArrayList<Car>
}更新：实际上，如果您将当前线程记录在RemoteViewFactory回调中，您将看到只有onCreate()在主线程上，其他回调在绑定器线程池的线程上工作。因此，在onDataSetChanged()中进行同步调用是可以的，因为它不在UI线程上，所以进行阻塞调用是可以的，您将不会得到ANR
页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/51580982
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