Question

I faced very strange problem. Writing an application to download some data from Internet with proxy server support I decided to use Apache’s HttpClient library. jar binaries were successfully added to NetBeans project and the following code snippet was executed (successfully too) in a simple application:

DefaultHttpClient httpclient = new DefaultHttpClient();
String proxyHost = "192.168.4.10";
Integer proxyPort = 8080;

HttpHost targetHost = new HttpHost("noaasis.noaa.gov", 80, "http");
HttpGet httpget = new HttpGet("/ptbus/ptbus167");

try {

    HttpHost proxy = new HttpHost(proxyHost, proxyPort);
    httpclient.getParams().setParameter(ConnRoutePNames.DEFAULT_PROXY, proxy);

    System.out.println("executing request: " + httpget.getRequestLine());
    System.out.println("via proxy: " + proxy);
    System.out.println("to target: " + targetHost);

    HttpResponse response = httpclient.execute(targetHost, httpget);
    HttpEntity entity = response.getEntity();

    System.out.println("----------------------------------------");
    System.out.println(response.getStatusLine());
    Header[] headers = response.getAllHeaders();
    for (int i = 0; i<headers.length; i++) {
        System.out.println(headers[i]);
    }

    System.out.println("----------------------------------------");
    System.out.println(response.getStatusLine());
    if (entity != null) {
        System.out.println("Response content length: " + entity.getContentLength());
    }
    EntityUtils.consume(entity);

}
catch (IOException ex) {

}
finally {
    // When HttpClient instance is no longer needed,
    // shut down the connection manager to ensure
    // immediate deallocation of all system resources
    httpclient.getConnectionManager().shutdown();
}

But when I try to do the same thing in Swing application it doesn’t work. For example, rewriting default Netbeans desktop application’s “about” action listener as follows

@Action
public void showAboutBox() {

    new Thread(new Runnable() {

        public void run() {

            DefaultHttpClient httpclient = new DefaultHttpClient();

            ......
            ......
            ......

            finally {
                // When HttpClient instance is no longer needed,
                // shut down the connection manager to ensure
                // immediate deallocation of all system resources
                httpclient.getConnectionManager().shutdown();
            }

        }
    }).start();
}

causes application’s execution to stop somewhere in

HttpResponse response = httpclient.execute(targetHost, httpget);

Leastways, it never returns…

The interesting thing is if I also put this code snippet in application’s main method just before creating any Swing instance the mentioned line is passed and HTTP response is received. And calling showAboutBox() doesn’t cause the problem anymore then – I receive HTTP response too.

What am I doing wrong, guys? What’s the trick? Can I use Apache’s library in my Swing application? I cannot understand what happens and didn’t find anything similar to this spending hours in the net.

Thank You for attention. Hope for any help!

Answer 1

I solved the problem by excluding org.jdesktop.application.SingleFrameApplication and replacing FrameView by JFrame. Of course, one loses advantages of FrameView but all required things can be implemented extending JFrame.

Unfortunately, I have no enough time to examine why HttpClient doesn’t work with SingleFrameApplication so the solution proposed is acceptable for me.

Hope this will help somebody else.

And thanks to trashgod and mKorbel for participation. Thank you, guys. Both +1.