以下是我的代码,我试图通过onProgressUpdate方法显示Asyntask中的进度,但它没有显示在警示对话框中。只有初始消息被显示。
class DownloadFileFromURL extends AsyncTask<String, String, String> {
private AlertDialog.Builder alert;
private int progress = 0;
/**
* Before starting background thread Show Progress Bar Dialog
*/
@Override
protected void onPreExecute() {
super.onPreExecute();
alert = new AlertDialog.Builder(context);
alert.setTitle("Downloading..");
alert.setMessage("1");
alert.setCancelable(false);
alert.show();
}
/**
* Downloading file in background thread
*/
@Override
protected String doInBackground(String... f_url) {
int count;
try {
URL url = new URL(f_url[0]);
URLConnection conection = url.openConnection();
conection.connect();
// this will be useful so that you can show a tipical 0-100%
// progress bar
int lenghtOfFile = conection.getContentLength();
// download the file
InputStream input = new BufferedInputStream(url.openStream(),
8192);
// Output stream
OutputStream output = new FileOutputStream(file);
byte data[] = new byte[1024];
long total = 0;
while ((count = input.read(data)) != -1) {
total += count;
// publishing the progress....
// After this onProgressUpdate will be called
publishProgress("" + (int) ((total * 100) / lenghtOfFile));
// writing data to file
output.write(data, 0, count);
}
// flushing output
output.flush();
// closing streams
output.close();
input.close();
} catch (Exception e) {
Log.e("Error: ", e.getMessage());
}
return null;
}
/**
* Updating progress bar
*/
@Override
protected void onProgressUpdate(String... progress) {
Log.d("Myapp","progress :"+progress[0]);
alert.setMessage(""+progress[0]);
}
/**
* After completing background task Dismiss the progress dialog
**/
@Override
protected void onPostExecute(String file_url) {
// dismiss the dialog after the file was downloaded
}
}
我在onProgressUpdate中也写了一条日志来显示进度更新,该日志已打印,但是onProgressUpdate中的alert.setMessage似乎没有将消息设置到我的警报对话框中。