取消AsyncTask的内部ListArrayAdapter和辞退通知 [英] Cancel AsyncTask inside ListArrayAdapter and dismiss notification
本文介绍了取消AsyncTask的内部ListArrayAdapter和辞退通知的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
应用程序的目的是提供一个简单的方法来下载并提取了一堆档案（〜200mo），要删除它，打开它。下载显示的显示进度的通知。
我用一个ListView显示每一个可以下载的存档。每个阵列包含一个图像，一些文字，和两个按钮（用于读/删除，下载，或取消）。这些数据来自一个JSON检索。
当我尝试取消其显示通知的AsyncTask并下载文件我有一些问题。当我打电话的 async.cancel（真）; 的，通知和下载仍在运行。
也许我是从错误的地方调用AsyncTask的，但我不知道如何解决这个问题。
我的适配器：
公共类ListArrayAdapter扩展ArrayAdapter＆LT;串GT; {私人最终上下文的背景下;
公众可绘制D组;
私人的ArrayList＆LT;＆HashMap的LT;字符串，字符串＆GT;＆GT;清单;
公共布尔finishDownload = FALSE;
JSONArray jsonArray;//构造
公共ListArrayAdapter（上下文的背景下，列表与LT;弦乐＆GT;的价值观，
ArrayList的＆LT;＆HashMap的LT;字符串，字符串＆GT;＆GT;名单）{
超（背景下，R.layout.activity_list_array_adapter，价值观）;
this.context =背景;
this.list =清单;
}@覆盖
公共查看getView（最终诠释的立场，观点convertView，父母的ViewGroup）{ LayoutInflater吹气=（LayoutInflater）上下文
.getSystemService（Context.LAYOUT_INFLATER_SERVICE）;
查看rowView = inflater.inflate（R.layout.activity_list_array_adapter，
父母，假）; //声明
TextView的日期=（TextView中）rowView.findViewById（R.id.date）;
TextView的标题=（TextView中）rowView.findViewById（R.id.title）;
TextView中描述=（TextView中）rowView.findViewById（R.id.description）;
ImageView的ImageView的=（ImageView的）rowView.findViewById（R.id.cover）;
进度PD =（进度）rowView.findViewById（R.id.progress）;
最终按钮按钮1 =（按钮）rowView.findViewById（R.id.button1）;
最后的按钮按钮2 =（按钮）rowView.findViewById（R.id.button2）; //装满JSON文件数组
title.setText（list.get（位置）获得（标题））;
date.setText（list.get（位置）获得（日期））;
description.setText（list.get（位置）获得（说明））;
新ParseImage（位置，ImageView的，PD）.execute（）; 最终文件的文件=新的文件（Environment.getExternalStorageDirectory（）
.getPath（）+/杂志/+ list.get（位置）获得（姓名）+.ZIP）; //如果文件存在，让用户打开它
如果（file.exists（））{
button1.setText（里拉）;
button2.setVisibility（View.VISIBLE）;
button2.setText（Supprimer）;
} //否则，让用户下载
其他{
button1.setText（Télécharger）;
button2.setVisibility（View.GONE）;
} 最后DownloadTask异步=新DownloadTask（上下文，位置，清单）; button1.setOnClickListener（新Button.OnClickListener（）{
@覆盖
公共无效的onClick（视图v）{
如果（button1.getText（）==Télécharger）{
button1.setEnabled（假）;
button2.setVisibility（View.VISIBLE）;
button2.setText（更改或取消）;
finishDownload = FALSE;
async.execute（0）;
}否则如果（button1.getText（）==里拉）{
意图I1 =新意图（背景下，WebActivity.class）;
context.startActivity（I1）;
}
}
}）; button2.setOnClickListener（新Button.OnClickListener（）{
@覆盖
公共无效的onClick（视图v）{
如果（button2.getText（）==更改或取消）{
async.cancel（真）;
button1.setEnabled（真）;
button2.setVisibility（View.GONE）;
button1.setText（Télécharger）;
}否则如果（button2.getText（）==Supprimer）{
button1.setEnabled（真）;
button2.setVisibility（View.GONE）;
button1.setText（Télécharger）; 如果（file.exists（））{
file.delete（）;
}
}
}
}）; 返回rowView;
}公共类DownloadTask扩展的AsyncTask＆LT;整数，整数，太虚＆GT; { 私人NotificationHelper mNotificationHelper;
公众诠释的位置;
公众的ArrayList＆LT;＆HashMap的LT;字符串，字符串＆GT;＆GT;清单; 公共DownloadTask（上下文的背景下，INT位置，
ArrayList的＆LT;＆HashMap的LT;字符串，字符串＆GT;＆GT;名单）{
mNotificationHelper =新NotificationHelper（背景）;
this.position =位置;
this.list =清单;
} @覆盖
在preExecute保护无效（）{
mNotificationHelper.createNotification（）;
} @覆盖
保护无效doInBackground（整数...整数）{
诠释计数= 0;
尝试{
视频下载（1）;
网址URL =新的URL（list.get（位置）获得（内容））;
URLConnection的连接如= url.openConnection（）;
conection.connect（）;
INT lenghtOfFile = conection.getContentLength（）; 输入的InputStream =新的BufferedInputStream（url.openStream（）
8192）; OutputStream的输出=新的FileOutputStream（环境
.getExternalStorageDirectory（）的getPath（）
+/杂志/
+ list.get（位置）获得（姓名）
+的.zip）; 字节的数据[] =新的字节[1024]; 总长= 0;
INT progress_temp = 0;
而（（计数= input.read（数据））！= - 1）
{
总+ =计数;
progress_temp =（int）的总* 100 / lenghtOfFile;
output.write（数据0，计）;
} publishProgress（progress_temp）;
output.flush（）;
output.close（）;
input.close（）; }赶上（例外五）{
Log.e（错误，e.getMessage（））;
}
返回null;
} @覆盖
保护无效onProgressUpdate（整数...进度）{
mNotificationHelper.progressUpdate（进展[0]）;
} @覆盖
保护无效onCancelled（）{
mNotificationHelper.completed（）; super.onCancelled（）;
} @覆盖
保护无效onPostExecute（虚空结果）{ mNotificationHelper.completed（）; finishDownload = TRUE;
}
}
}
该notificationHelper类管理的通知：
公共类NotificationHelper {
私人语境mContext;
私人INT NOTIFICATION_ID = 1;
私人通知mNotification;
私人NotificationManager mNotificationManager;
私人的PendingIntent mContentIntent;
私人CharSequence的mContentTitle; 公共NotificationHelper（上下文的背景下）{
mContext =背景;
} @燮pressWarnings（德precation）
公共无效createNotification（）{
mNotificationManager =（NotificationManager）mContext
.getSystemService（Context.NOTIFICATION_SERVICE）; INT图标= android.R.drawable.stat_sys_download;
CharSequence的tickerText = mContext.getString（R.string.download_ticker）;
时长= System.currentTimeMillis的（）;
mNotification =新的通知（图标，tickerText时）; mContentTitle = mContext.getString（R.string.content_title）;
的CharSequence contentText =0％téléchargé; 意图notificationIntent =新意图（mContext，MainActivity.class）;
mContentIntent = PendingIntent.getActivity（mContext，0，
notificationIntent，0）; mNotification.setLatestEventInfo（mContext，mContentTitle，contentText，
mContentIntent）; mNotification.flags = Notification.FLAG_ONGOING_EVENT; mNotificationManager.notify（NOTIFICATION_ID，mNotification）;
} @燮pressWarnings（德precation）
公共无效progressUpdate（INT percentageComplete）{
CharSequence的contentText = percentageComplete +％téléchargé; mNotification.setLatestEventInfo（mContext，mContentTitle，contentText，
mContentIntent）;
mNotificationManager.notify（NOTIFICATION_ID，mNotification）;
} 公共无效完成（）{
mNotificationManager.cancel（NOTIFICATION_ID）;
}
}
解决方案
的取消（）在 AsyncTasks 方法（容易混淆）实际上并没有停止运行线程，而是设置一个标志的任务。你可以在这里找到有关一些讨论。如此看来，目前，如果你想你的线程真正停止中旬执行，你需要使用手动检查标志在你的循环code中的 isCancelled（）方法。例如，在doInBackground while循环
，而（（数= input.read（数据））！= -1）
{
总+ =计数;
progress_temp =（int）的总* 100 / lenghtOfFile;
output.write（数据0，计）;
如果（isCancelled（））
{
// code在这里，可能...
//跳出循环，
//停止线程，
//关闭通知，
//执行任何清理，等等。
}
}
下可以找到用法这在AsyncTask的文档另一个例子头。希望这有助于！
The aim of the application is to offer a simple way to download and extract a bunch of archives (~200mo), to delete it, and to open it. The download display a notification which display the progress.
I'm using a ListView to display every archive that can be downloaded. Each array contain an image, some text, and two buttons (for reading/deleting, downloading, or cancel). The data are retrieved from a json.
I've got some issues while I try to cancel the AsyncTask which display the notification and download the file. When I call the async.cancel(true);, the notification and the download are still running.
Maybe am I calling the asyncTask from the wrong place, but I don't know how to fix this.
My adapter :
public class ListArrayAdapter extends ArrayAdapter<String> {
private final Context context;
public Drawable d;
private ArrayList<HashMap<String, String>> list;
public boolean finishDownload = false;
JSONArray jsonArray;
// Constructor
public ListArrayAdapter(Context context, List<String> values,
ArrayList<HashMap<String, String>> list) {
super(context, R.layout.activity_list_array_adapter, values);
this.context = context;
this.list = list;
}
@Override
public View getView(final int position, View convertView, ViewGroup parent) {
LayoutInflater inflater = (LayoutInflater) context
.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
View rowView = inflater.inflate(R.layout.activity_list_array_adapter,
parent, false);
// Déclaration
TextView date = (TextView) rowView.findViewById(R.id.date);
TextView title = (TextView) rowView.findViewById(R.id.title);
TextView description = (TextView) rowView.findViewById(R.id.description);
ImageView imageView = (ImageView) rowView.findViewById(R.id.cover);
ProgressBar pd = (ProgressBar) rowView.findViewById(R.id.progress);
final Button button1 = (Button) rowView.findViewById(R.id.button1);
final Button button2 = (Button) rowView.findViewById(R.id.button2);
// Fill the array with the json file
title.setText(list.get(position).get("Title"));
date.setText(list.get(position).get("Date"));
description.setText(list.get(position).get("Description"));
new ParseImage(position, imageView, pd).execute();
final File file = new File(Environment.getExternalStorageDirectory()
.getPath() + "/Magazine/" + list.get(position).get("Name") + ".zip");
//If the file exist, let the user open it
if (file.exists()) {
button1.setText("Lire");
button2.setVisibility(View.VISIBLE);
button2.setText("Supprimer");
}
// else, let the user download it
else {
button1.setText("Télécharger");
button2.setVisibility(View.GONE);
}
final DownloadTask async = new DownloadTask(context, position, list);
button1.setOnClickListener(new Button.OnClickListener() {
@Override
public void onClick(View v) {
if (button1.getText() == "Télécharger") {
button1.setEnabled(false);
button2.setVisibility(View.VISIBLE);
button2.setText("Annuler");
finishDownload = false;
async.execute(0);
} else if (button1.getText() == "Lire") {
Intent i1 = new Intent(context, WebActivity.class);
context.startActivity(i1);
}
}
});
button2.setOnClickListener(new Button.OnClickListener() {
@Override
public void onClick(View v) {
if (button2.getText() == "Annuler") {
async.cancel(true);
button1.setEnabled(true);
button2.setVisibility(View.GONE);
button1.setText("Télécharger");
} else if (button2.getText() == "Supprimer") {
button1.setEnabled(true);
button2.setVisibility(View.GONE);
button1.setText("Télécharger");
if (file.exists()) {
file.delete();
}
}
}
});
return rowView;
}
public class DownloadTask extends AsyncTask<Integer, Integer, Void> {
private NotificationHelper mNotificationHelper;
public int position;
public ArrayList<HashMap<String, String>> list;
public DownloadTask(Context context, int position,
ArrayList<HashMap<String, String>> list) {
mNotificationHelper = new NotificationHelper(context);
this.position = position;
this.list = list;
}
@Override
protected void onPreExecute() {
mNotificationHelper.createNotification();
}
@Override
protected Void doInBackground(Integer... integers) {
int count = 0;
try {
Thread.sleep(1);
URL url = new URL(list.get(position).get("Content"));
URLConnection conection = url.openConnection();
conection.connect();
int lenghtOfFile = conection.getContentLength();
InputStream input = new BufferedInputStream(url.openStream(),
8192);
OutputStream output = new FileOutputStream(Environment
.getExternalStorageDirectory().getPath()
+ "/Magazine/"
+ list.get(position).get("Name")
+ ".zip");
byte data[] = new byte[1024];
long total = 0;
int progress_temp = 0;
while ((count=input.read(data)) != -1)
{
total += count;
progress_temp = (int) total*100/lenghtOfFile;
output.write(data, 0, count);
}
publishProgress(progress_temp);
output.flush();
output.close();
input.close();
} catch (Exception e) {
Log.e("Error: ", e.getMessage());
}
return null;
}
@Override
protected void onProgressUpdate(Integer... progress) {
mNotificationHelper.progressUpdate(progress[0]);
}
@Override
protected void onCancelled() {
mNotificationHelper.completed();
super.onCancelled();
}
@Override
protected void onPostExecute(Void result) {
mNotificationHelper.completed();
finishDownload = true;
}
}
}
The notificationHelper class which manage the notification :
public class NotificationHelper {
private Context mContext;
private int NOTIFICATION_ID = 1;
private Notification mNotification;
private NotificationManager mNotificationManager;
private PendingIntent mContentIntent;
private CharSequence mContentTitle;
public NotificationHelper(Context context) {
mContext = context;
}
@SuppressWarnings("deprecation")
public void createNotification() {
mNotificationManager = (NotificationManager) mContext
.getSystemService(Context.NOTIFICATION_SERVICE);
int icon = android.R.drawable.stat_sys_download;
CharSequence tickerText = mContext.getString(R.string.download_ticker);
long when = System.currentTimeMillis();
mNotification = new Notification(icon, tickerText, when);
mContentTitle = mContext.getString(R.string.content_title);
CharSequence contentText = "0% téléchargé";
Intent notificationIntent = new Intent(mContext, MainActivity.class);
mContentIntent = PendingIntent.getActivity(mContext, 0,
notificationIntent, 0);
mNotification.setLatestEventInfo(mContext, mContentTitle, contentText,
mContentIntent);
mNotification.flags = Notification.FLAG_ONGOING_EVENT;
mNotificationManager.notify(NOTIFICATION_ID, mNotification);
}
@SuppressWarnings("deprecation")
public void progressUpdate(int percentageComplete) {
CharSequence contentText = percentageComplete + "% téléchargé";
mNotification.setLatestEventInfo(mContext, mContentTitle, contentText,
mContentIntent);
mNotificationManager.notify(NOTIFICATION_ID, mNotification);
}
public void completed() {
mNotificationManager.cancel(NOTIFICATION_ID);
}
}
解决方案
The cancel() method on AsyncTasks (confusingly) doesn't actually stop the Thread from running, but rather sets a flag on the Task. You can find some discussion about that here. It seems that currently, if you want your Thread to actually stop mid-execution, you'll need to manually check that flag in your looping code using the isCancelled() method. For example, in your while loop in doInBackground:
while ((count=input.read(data)) != -1)
{
total += count;
progress_temp = (int) total*100/lenghtOfFile;
output.write(data, 0, count);
if(isCancelled())
{
//Code here that may...
// break out of the loop,
// stop the thread,
// close the notification,
// perform any cleanup, etc...
}
}
You can find another example of this in the AsyncTask docs under the "Usage" header. Hope this helps!
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