I need to disconnect a long polling http request from the client side in some cases. The relevant part of the HttpUrlConnection I make to the server is as follows (all the code below is within a Thread's run() method):
try {
URL url = new URL(requestURL);
connection = (HttpURLConnection) url.openConnection();
connection.setRequestProperty("Accept-Charset", "UTF-8");
connection.setConnectTimeout(5 * 1000);
connection.setReadTimeout(60 * 1000);
connection.setRequestMethod("GET");
// read the output from the server
reader = new BufferedReader(new InputStreamReader(connection.getInputStream()));
StringBuilder stringBuilder = new StringBuilder();
String line = null;
while ((line = reader.readLine()) != null) {
stringBuilder.append(line + "\n");
}
Log.d(TAG, stringBuilder);
} catch (IOException ioe) {
Log.e(TAG, ioe);
} finally {
if (reader != null) {
try {
reader.close();
} catch (IOException ioe) {
ioe.printStackTrace();
}
}
}
This is how I first initiate, then (after a second delay) try to cancel the request:
pollThread = new PollThread();
pollThread.start();
Log.d(TAG, "pollThread started");
new Handler().postDelayed(new Runnable() {
@Override
public void run() {
pollThread.cancelRequest();
Log.d(TAG, "pollThread presumably cancelled");
}
}, 1000);
And this is what the cancelRequest() method looks like:
public void cancelRequest() {
if (connection != null) {
connection.disconnect();
}
}
So essentially,
And this is exactly what happens on various emulators (2.2 - 4.0.3), a Motorola Atrix (2.3.7) and a Samsung Note (4.0.1). But on some HTC devices running 2.2, the request will stay alive and it will recieve the response, despite the fact that I explicitly terminated the connection. I verified this with an HTC Desire and an HTC Wildfire.
What's going on here? How can I cancel such a request safely on all devices running 2.2+?
For your convenience, the whole code is available here, should you like to do a test drive yourself: https://gist.github.com/3306225
This is a known bug in earlier android release (Froyo 2.2) which, in sort, sockets can not be closed asynchronously by other threads, and has been fixed in Gingerbread 2.3:
Issue 11705: impossible to close HTTP connection using HttpURLConnection
Comments from project member in that link:
The best approximation of this that will work in current releases is to set read and connect timeouts on the HTTP connection.
Hope that helps.