[英]publishing progress in shared class in doBackgorund in AsyncTask
[英]AsyncTask is publishing progress after cancelled
我的情况是可以下载发票的RecyclerView。 他们具有启动下载并在“下载”按钮本身周围的圆形进度视图中显示进度的操作。 我使用AsyncTask通过自定义侦听器下载PDF格式的特定发票,因此我知道何时在AsyncTask本身之外取消,执行和更新进度(以避免在AsyncTask内部通过View并对其进行更新)。
到目前为止,这是我的AsyncTask:
public class DownloadTask extends AsyncTask<URL, Integer, String> implements Codes {
private AsyncTaskProgressListener listener;
private File file;
public DownloadTask(AsyncTaskProgressListener listener) {
this.listener = listener;
}
@Override
protected String doInBackground(URL... urls) {
InputStream input = null;
OutputStream output = null;
HttpURLConnection connection = null;
try {
URL url = urls[0];
file = new File(Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS) + "/" + url.getFile());
connection = (HttpURLConnection) url.openConnection();
connection.connect();
if (connection.getResponseCode() != HttpURLConnection.HTTP_OK) {
return "Server returned HTTP " + connection.getResponseCode()
+ " " + connection.getResponseMessage();
}
int fileLength = connection.getContentLength();
LogUtil.log("" + fileLength);
// download the file
input = connection.getInputStream();
output = new FileOutputStream(new File(Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS), url.getFile()));
byte data[] = new byte[4096];
long total = 0;
int count;
int lastProgress = 0;
while ((count = input.read(data)) != -1) {
if (isCancelled()) {
break;
}
total += count;
// publishing the progress....
int progress = 0;
if (fileLength > 0) {
// only if total length is known
progress = (int) (total * 100 / fileLength);
}
//Prevent publishing the same progress various times as it would freeze the progress bar.
if (progress > lastProgress) {
publishProgress(progress);
lastProgress = progress;
}
output.write(data, 0, count);
}
} catch (Exception e) {
LogUtil.log(e.toString());
return e.toString();
} finally {
try {
if (output != null)
output.close();
if (input != null)
input.close();
} catch (IOException e) {
e.printStackTrace();
}
if (connection != null)
connection.disconnect();
}
return null;
}
@Override
protected void onProgressUpdate(Integer... values) {
super.onProgressUpdate(values);
listener.onProgressUpdated(values[0]);
}
@Override
protected void onPostExecute(String s) {
super.onPostExecute(s);
listener.onCompleted();
}
@Override
protected void onCancelled(String s) {
listener.onCancel();
file.delete();
LogUtil.log("CANCELED");
super.onCancelled(s);
//noinspection ResultOfMethodCallIgnored
}
}
而我的听众:
tasks[0] = new DownloadTask(new AsyncTaskProgressListener() {
@Override
public void onCompleted() {
state = INVOICE_DOWNLOADED;
}
@Override
public void onCancel() {
state = INVOICE_NOT_DOWNLOADED;
progressView.resetAnimation();
}
@Override
public void onProgressUpdated(int progress) {
progressView.setProgress(progress);
}
});
当我按下取消按钮时,这就是所谓的:
progressView.setProgress(0);
if (tasks[0] != null)
tasks[0].cancel(true);
最后是我的问题:我发现当取消下载时(主要是在下载50%之后onProgressUpdated(progress)
在progressView.setProgress(0)
之后最后一次调用了onProgressUpdated(progress)
,因此取消了下载,但进度条卡住了最后的进度而不是0(设置新进度时,它会以非常酷的方式进行动画处理)。
我试图以各种方式来解决此,就像上的AsyncTask一个布尔值,知道它是否取消,它设置为true的方法,以及它在一个检查onProgressUpdated(progress)
的的AsyncTask的调用之前onProgressUpdated(progress)
设置视图进度的侦听器; 我无法找到解决方案。
onProgressUpdated()
和progressView.setProgress(0);
两者都在UI线程上运行,因此您可以对其添加布尔检查。
boolean noMoreProgressUpdate = false
progressView.setProgress(0);
之后添加noMoreProgressUpdate = true
progressView.setProgress(0);
更改
public void onProgressUpdated(int progress) { progressView.setProgress(progress); }
至
`
public void onProgressUpdated(int progress) {
if(!noMoreProgressUpdate) {
progressView.setProgress(progress);
}
}
`
我会用
onPreExecute() {
//do progress bar here
}
然后在onPostExecute()
onPostExecute(String result) {
//dismiss progress bar before anything else
}
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