当我在一个线程中运行它时，它工作得很好，但是我想使用Asynctask，当我执行它的版本时，没有任何反应：
try {
//set the download URL, a url that points to a file on the internet
//this is the file to be downloaded
URL url = new URL(filename2);
//create the new connection
HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection();
//set up some things on the connection
urlConnection.setRequestMethod("GET");
urlConnection.setDoOutput(true);
//and connect!
urlConnection.connect();
//set the path where we want to save the file
//in this case, going to save it on the root directory of the
//sd card.
SDCardRoot = Environment.getExternalStorageDirectory() + "/download/";
//create a new file, specifying the path, and the filename
//which we want to save the file as.
File file = new File(SDCardRoot,filename3);
//this will be used to write the downloaded data into the file we created
FileOutputStream fileOutput = new FileOutputStream(file);
//this will be used in reading the data from the internet
InputStream inputStream = urlConnection.getInputStream();
//this is the total size of the file
//int totalSize = urlConnection.getContentLength();
//variable to store total downloaded bytes
int downloadedSize = 0;
//create a buffer...
byte[] buffer = new byte[1024];
int bufferLength = 0; //used to store a temporary size of the buffer
//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
//updateProgress(downloadedSize, totalSize);
//publishProgress((int)(total*100/lenghtOfFile));
}
//close the output stream when done
fileOutput.close();
//catch some possible errors...
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
这是我要求的尝试：
private class DownloadFile extends AsyncTask<Void, Integer, Long> {
protected void onProgressUpdate(Integer... progress) {
}
protected void onPostExecute(Long result) {
Intent in = new Intent(mainmenu.this, DownloadService.class);
stopService(in);
}
@Override
protected Long doInBackground(Void... params) {
try {
//set the download URL, a url that points to a file on the internet
//this is the file to be downloaded
URL url = new URL(filename2);
//create the new connection
HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection();
//set up some things on the connection
urlConnection.setRequestMethod("GET");
urlConnection.setDoOutput(true);
//and connect!
urlConnection.connect();
//set the path where we want to save the file
//in this case, going to save it on the root directory of the
//sd card.
SDCardRoot = Environment.getExternalStorageDirectory() + "/download/";
//create a new file, specifying the path, and the filename
//which we want to save the file as.
File file = new File(SDCardRoot,filename3);
//this will be used to write the downloaded data into the file we created
FileOutputStream fileOutput = new FileOutputStream(file);
//this will be used in reading the data from the internet
InputStream inputStream = urlConnection.getInputStream();
//this is the total size of the file
//int totalSize = urlConnection.getContentLength();
//variable to store total downloaded bytes
int downloadedSize = 0;
//create a buffer...
byte[] buffer = new byte[1024];
int bufferLength = 0; //used to store a temporary size of the buffer
//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
//updateProgress(downloadedSize, totalSize);
//publishProgress((int)(total*100/lenghtOfFile));
}
//close the output stream when done
fileOutput.close();
//catch some possible errors...
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
return null;
}
}
答案 0 :(得分：0)
你去吧
public class WebRequest extends AsyncTask<URL, Void, String> {
ProgressDialog dialog;
Context _context;
String _title;
String _message;
public WebRequest(Context context,
String ProgressTitle, String ProgressMessage) {
this._context = context;
this._title = ProgressTitle;
this._message = ProgressMessage;
}
@Override
protected void onPreExecute() {
// TODO Auto-generated method stub
dialog = new ProgressDialog(_context);
dialog.setTitle(_title);
dialog.setMessage(_message);
dialog.show();
}
@Override
protected String doInBackground(URL... params) {
// TODO Auto-generated method stub
try {
//set the download URL, a url that points to a file on the internet
//this is the file to be downloaded
URL url = params[0];
//create the new connection
HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection();
//set up some things on the connection
urlConnection.setRequestMethod("GET");
urlConnection.setDoOutput(true);
//and connect!
urlConnection.connect();
//set the path where we want to save the file
//in this case, going to save it on the root directory of the
//sd card.
SDCardRoot = Environment.getExternalStorageDirectory() + "/download/";
//create a new file, specifying the path, and the filename
//which we want to save the file as.
File file = new File(SDCardRoot,filename3);
//this will be used to write the downloaded data into the file we created
FileOutputStream fileOutput = new FileOutputStream(file);
//this will be used in reading the data from the internet
InputStream inputStream = urlConnection.getInputStream();
//this is the total size of the file
//int totalSize = urlConnection.getContentLength();
//variable to store total downloaded bytes
int downloadedSize = 0;
//create a buffer...
byte[] buffer = new byte[1024];
int bufferLength = 0; //used to store a temporary size of the buffer
//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
//updateProgress(downloadedSize, totalSize);
//publishProgress((int)(total*100/lenghtOfFile));
}
//close the output stream when done
fileOutput.close();
return "Success";
//catch some possible errors...
} catch (MalformedURLException e) {
e.printStackTrace();
return "Failed";
} catch (IOException e) {
e.printStackTrace();
return "Failed";
}
}
@Override
protected void onPostExecute(String result) {
// TODO Auto-generated method stub
if (dialog.isShowing())
dialog.cancel();
Toast.makeText(_context,result,Toast.LENGTH_LONG);
}
}
//使用此
WebRequest request = new WebRequest(context,"Downloading","Please wait..");
request.Execute(object of URL);