下载大文件时，AsynTask仍在运行时，ProgrressDialog会出现混乱
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在实现AsynTask和ProgressDialog时，我有一个扼杀行为。当我下载小文件时，一切正常，进度状态从0％更新为100％。但是，当我下载较大的文件时，ProgressDialog上的数字将达到6或7％，然后不再更新。但是，在2,3分钟后，我收到一条消息，表明asyntask任务已完成下载过程。
public class DownloadHelper extends AsyncTask<String, Integer, Long> implements DialogInterface.OnDismissListener{
private volatile boolean running = true;
private PhonegapActivity _ctx = null;
private ProgressDialog _progressDialog = null;
private String _title = null;
private File _root = null;
private File _destination = null;
private DatabaseHelper _dbHelper = null;
private Cursor _cursorMedia = null;
public DownloadHelper(String title, File root, File destination, DatabaseHelper dbHelper, PhonegapActivity ctx){
_title = title;
_ctx = ctx;
_root = root;
_destination = destination;
_dbHelper = dbHelper;
}
@Override
protected void onPreExecute() {
if (_progressDialog != null)
{
_progressDialog.dismiss();
_progressDialog = null;
}
_progressDialog = new ProgressDialog(_ctx);
_progressDialog.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);
_progressDialog.setTitle(\"Downloading\");
_progressDialog.setMessage(_title);
_progressDialog.setCancelable(true);
_progressDialog.setMax(100);
_progressDialog.setProgress(0);
/*_progressDialog.setOnCancelListener(
new DialogInterface.OnCancelListener() {
public void onCancel(DialogInterface dialog) {
_progressDialog = null;
running = false;
}
});
_progressDialog.setOnDismissListener(
new DialogInterface.OnDismissListener() {
public void onDismiss(DialogInterface dialog) {
Log.d(\"DownloadHelper\", \"canceled inside listener\");
_progressDialog = null;
running = false;
}
}
);*/
_progressDialog.show();
running = true;
}
@Override
protected Long doInBackground(String... sUrl) {
try {
Log.d(\"DownloadHelper\", \"Start download from url \" + sUrl[0]);
long total = 0;
total = _download(sUrl[0], _destination);
return total;
} catch (Exception ex2) {
ex2.printStackTrace();
Log.d(\"DownloadHelper\", \"Failed to download test file from \" + sUrl[0] + \" to \" + _destination.getAbsolutePath().toString());
_closeProgressDialog();
}
return null;
}
protected void onCancelled(Long result) {
Log.d(\"DownloadHelper\", \"CANCELLED result = \" + result);
_closeProgressDialog();
}
protected void onProgressUpdate(Integer... progress) {
if (_progressDialog != null && running)
{
Log.d(\"DownloadHelper\", \"UPDATED progess = \" + progress[0]);
_progressDialog.setProgress(progress[0]);
}
else //cancel the task
{
Log.d(\"DownloadHelper\", \"onProgressUpdate cancelled\");
cancel(true);
}
}
protected void onPostExecute(Long result) {
Log.d(\"DownloadHelper\", \"FINISHED result = \" + result);
// Close the ProgressDialog
_closeProgressDialog();
running = false;
if (result != null) //OK
{
_showAlertDialog(\"Test has been downloaded successfully.\", \"Message\", \"OK\");
}
else // error
{
_showAlertDialog(\"Can not download the test. Please try again later.\", \"Error\", \"OK\");
}
}
@Override
protected void onCancelled() {
running = false;
}
public void onDismiss(DialogInterface dialog) {
Log.d(\"DownloadHelper\", \"Cancelled\");
this.cancel(true);
}
protected void _closeProgressDialog(){
if (_progressDialog != null)
{
_progressDialog.dismiss();
_progressDialog = null;
}
}
protected void _showAlertDialog(final String message, final String title, final String buttonLabel){
AlertDialog.Builder dlg = new AlertDialog.Builder(_ctx);
dlg.setMessage(message);
dlg.setTitle(title);
dlg.setCancelable(false);
dlg.setPositiveButton(buttonLabel,
new AlertDialog.OnClickListener() {
public void onClick(DialogInterface dialog, int which) {
dialog.dismiss();
}
});
dlg.create();
dlg.show();
}
protected Cursor _checkMedia() {
_dbHelper.openDatabase(_destination.getAbsolutePath());
Log.d(\"DownloadHelper\", \"Database is opened\");
String[] columns = {\"type, size, location, location_id, url\"};
Cursor cursor = _dbHelper.get(\"media\", columns);
_dbHelper.closeDatabase();
_dbHelper.close();
_dbHelper = null;
return cursor;
}
protected long _download(String sUrl, File destination) throws IOException {
URL url = new URL(sUrl);
URLConnection conexion = url.openConnection();
conexion.connect();
// this will be useful so that you can show a tipical 0-100% progress bar
int lenghthOfFile = conexion.getContentLength();
Log.d(\"DownloadHelper\", \"length of File = \" + lenghthOfFile);
// downlod the file
InputStream input = new BufferedInputStream(url.openStream());
OutputStream output = new FileOutputStream(destination);
byte data[] = new byte[1024];
long total = 0;
int count;
// Reset the progress
_progressDialog.setProgress(0);
// Start downloading main test file
while ((count = input.read(data)) != -1 && running) {
total += count;
Log.d(\"DownloadHelper\", \"total = \" + total);
// publishing the progress....
this.publishProgress((int)(total*100/lenghthOfFile));
output.write(data, 0, count);
}
if (running == false)
{
this.cancel(true);
}
output.flush();
output.close();
input.close();
return total;
}
}
D/DownloadHelper( 1666): length = **3763782**; total = 77356; percent = 2; save_percent = 0
D/DownloadHelper( 1666): UPDATED progess = 2
D/DownloadHelper( 1666): length = 3763782; total = 230320; percent = 6; save_percent = 0
D/DownloadHelper( 1666): UPDATED progess = 6
D/dalvikvm( 1666): GC freed 10241 objects / 1087168 bytes in 88ms
*D/DownloadHelper( 1666): FINISHED result = **230320***
OSNetworkSystem.receiveStreamImpl(FileDescriptor, byte[], int, int, int) line: not available [native method]
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try { // this is the file to be downloaded final URL url = new URL(Url); // set the download URL, a url that // points to a file on the internet // create the new connection final HttpURLConnection urlConnection = (HttpURLConnection) url .openConnection(); // set up some things on the connection and connect! urlConnection.setRequestMethod(\"GET\"); urlConnection.setDoOutput(true); urlConnection.setConnectTimeout(4500); // Connection timeout in // miliseconds urlConnection.connect(); Log.i(TAG, \"Connected\"); // set the path where we want to save the file // in this case on root directory of the // sd card. File directory = new File(Environment.getExternalStorageDirectory().getAbsoluteFile()+MUSIC_VIDEOS_PATH+artist); // create a new file, specifying the path, and the filename // which we want to save the file as. directory.mkdirs(); // If we want to save the file in another // directory on the SD card // we need to make the directories if they dont exist. // you can download to any type of file ex: (image), (text file), // (audio file) Log.i(TAG, \"File Name:\" + filename); final File file = new File(directory, filename); if (file.createNewFile()) { file.createNewFile(); } // this will be used to write the downloaded data into the file we // created final FileOutputStream fileOutput = new FileOutputStream(file); // this will be used in reading the data from the internet final InputStream inputStream = urlConnection.getInputStream(); // this is the total size of the file final int totalSize = urlConnection.getContentLength(); // variable to store total downloaded bytes int downloadedSize = 0; // a buffer final byte[] buffer = new byte[1024*1024]; int bufferLength = 0; // used to store a temporary size of the // buffer int lastProgress = 0, progress = 0; // now, read through the input buffer and write the contents to the // file while ((bufferLength = inputStream.read(buffer)) > 0) { // add the data in the buffer to the file in the file output // stream (the file on the sd card fileOutput.write(buffer, 0, bufferLength); // add up the size so we know how much is downloaded downloadedSize += bufferLength; // this is where you would do something to report the prgress, // like this maybe // Log.i(\"Progress:\",\"downloadedSize:\"+String.valueOf((int)((downloadedSize/(double)totalSize)*100))+\" % totalSize:\"+ // totalSize) ; progress = (int) ((downloadedSize / (double) totalSize) * 100); if (progress != lastProgress && progress % 10 == 0) { notification.contentView.setProgressBar(R.id.ProgressBar01, 100, progress, false); // inform the progress bar of updates in progress nm.notify(id, notification); Log.i(TAG, String.valueOf(progress)); } lastProgress = progress; } // close the output stream when done fileOutput.flush(); fileOutput.close();孤捷侩
而不是一个对象）。int lengthOfFile = conexion.getContentLength(); // note spelling :) int tickSize = 2 * lengthOfFile / 100; // adjust to how often you want to update progress, this is 2% int nextProgress = tickSize; // ... while ((count = input.read(data)) != -1 && running) { total += count; if (total >= nextProgress) { nextProgress = (total / tickSize + 1) * tickSize; this.publishProgress((int)(total*100/lengthOfFile)); } output.write(data, 0, count); } // ...