crafterm's weblog

java.net.HttpURLConnection!

Found out an interesting surprise today with the java.net.HttpURLConnection class.
Take a look at the two following code fragments:

URL url = new URL("http://localhost:8080/something/somewhere/");
URLConnection conn = url.openConnection();
HttpURLConnection c = (HttpURLConnection) conn;
System.out.println("1." + c.getInputStream());
System.out.println("2." + c.getLastModified());
System.out.println("3." + c.getContentType());
System.out.println("4." + c.getResponseCode());


and

URL url = new URL("http://localhost:8080/something/somewhere/");
URLConnection conn = url.openConnection();
HttpURLConnection c = (HttpURLConnection) conn;
System.out.println("2." + c.getLastModified());
System.out.println("3." + c.getContentType());
System.out.println("4." + c.getResponseCode());
System.out.println("1." + c.getInputStream());


(simple reordering of the call to getInputStream())

I expected both fragments to yield the same results, however there's a hidden surprise here - if the location you point your URL object to does not exist, then the first fragment will raise a FileNotFoundException (as expected), but the second one will give you an InputStream containing the error page from the server!

This certainly had me on a wild goose chase for an hour! :)

Update:

Ok, looks like this is a problem specific to JDK 1.3.1, JDK 1.4.x exhibits correct behaviour.

Posted by crafterm at June 27, 2003 07:07 PM | TrackBack