Cancel/abort a connection from the ThreadSafeClientConnManager connection pool

Question

I'm using ThreadSafeClientConnManager to manage a pool of client connections, because my application has several threads, which are simultaneously connecting to a webserver.

Abstract sample code:

HttpClient httpClient;
ClientConnectionManager conMgr = new ThreadSafeClientConnManager(parameters,schReg);
httpclient = new DefaultHttpClient(conMgr, parameters);

Now lets say on of this threads is downloading a large file, but then the user of my application is switching to another activity/screen. Therefor the file is needless and I'd like to abort this download connection.

In ThreadSafeClientConnManager I found this method:

public ClientConnectionRequest requestConnection (HttpRoute route, Object state) Returns a new ClientConnectionRequest, from which a ManagedClientConnection can be obtained or the request can be aborted.

So far I've been using:

HttpGet httpRequest = new HttpGet(URL_TO_FILE);
HttpResponse response = (HttpResponse) httpclient.execute(httpRequest);
[...]

Now from what I understand, I've to use:

httpclient.getConnectionManager().requestConnection(HttpRoute route, Object state);

And that's the point where I'm stuck. I assume that for the route I can just use new HttpRoute(new HttpHost("10.0.0.1")) or whatever my server is, but what to put in for Object state?

And second, as soon as I've the ClientConnectionManager I can call getConnection(long timeout, TimeUnit tunit). But then from there, how I do I execute my HttpGet httpRequest = new HttpGet(URL_TO_FILE); as I did before with HttpResponse response = (HttpResponse) httpclient.execute(httpRequest);?

I've been gone through the documentation and tried out quite a few different things, but I wasn't able to obtain a working solution. Therefor any suggestions and/or code examples are more than welcome.

Answer 1

You just need to call httpRequest.abort() and the connection should be closed.

With a large file, you must have a loop process the data. You can just check the cancel status and abort from there,

    HttpEntity entity = response.getEntity();
    if (entity != null) {
        InputStream instream = entity.getContent();
        while (instream.read(buf) >= 0) {
            if (cancelled)
               httpRequest.abort();
            // Process the file
        }
     }

When pooling or keepalive is used, the aborted connection can't be returned to the pool and it must be closed. There was a bug in older versions that the connection is kept alive and it messes up next request. I think this is all fixed.