What's it all about, Alfie?

I got a request from a co-worker late yesterday to add in a timeout to the AJAX gathering code in my web app. It wasn't immediately obvious, but I spent just a few minutes and it turned out to be pretty simple after all. It's used when you need to pull in an XML file from a URL for parsing into a DOM. Not hard, but very important to get right, and in a nicely flexible way.

If you start with the code I had originally:

  InputSource    retval = null;
  URL   source = ...;
 
  try {
    retval = new InputSource(new InputStreamReader(source.openStream()));
  } catch (IOException ioe) {
    if (!ioe.getMessage().equals("Connection refused") &&
        !ioe.getMessage().startsWith("Server returned HTTP response code: 500 ")) {
      log.error("While trying to get the data from the URL, an IOException occurred: "
          + ioe.getMessage();
    }
  }

and then finally read in the JavaDocs that the call:

  source.openStream()

is really just:

  source.openConnection().getInputStream()

So the code can quickly become:

  InputSource    retval = null;
  URL   source = ...;
 
  try {
    URLConnection  conn = source.openConnection();
    if (conn != null) {
      if (aTimeoutMSec > 0) {
        conn.setReadTimeout(aTimeoutMSec);
      }
      retval = new InputSource(new InputStreamReader(conn.getInputStream()));
    }
  } catch (IOException ioe) {
    if (!ioe.getMessage().equals("Connection refused") &&
        !ioe.getMessage().startsWith("Server returned HTTP response code: 500 ")) {
      log.error("While trying to get the data from the URL, an IOException occurred: "
          + ioe.getMessage();
    }
  }

In the end, we added in more logging - even a stack trace by a co-worker to help them find out what the problem was with a server-side error. But I have to admit, Java isn't as clear as it could be on things like this. But the JavaDocs did have what I needed, and that was enough to find out what I needed.

This entry was posted on Wednesday, January 6th, 2010 at 8:03 am and is filed under Coding, Cube Life. You can follow any responses to this entry through the RSS 2.0 feed. Both comments and pings are currently closed.