A content length will only be returned if the HTTP header of Content-Length has been set. This wouldn't normally be set for a static web page (if it can even be set?). It is more likely to be set if the page is programatically generated such as from a servlet which "knows" the size of the page that it is outputting.
int size = response.getText().length();
to get the length of the response excluding headers. You should find it returns 115kb.
IF you are testing the header objects, the prior answer won't work.
To get back to your original question...
Your post is wrong. It's not that httpunit deprecated, but Java deprecated some calls in their java.net class that httpunit depends on. You have several options.
1. Go back to older build of java. You don't always need to have the latest and greatest for 'testing' purpose. I stick with a working one as long as I can.
2. Download the latest httpunit. Maybe they fixed the deprecated calls? The last release was in October so if you are using a JDK newer then the latest version, you may be out of luck.
3. Get the source of httpunit, fix it, then submit it back to httpunit project. (Hell, I've submitted code to Ant project to fix bugs...).
First two is ideal. I would guess the third is out of question as you'd probably done that by now. If you download their source, and simply compile it, you will see all the deprecation errors/warning.
NOTE: I also use httpunit, but we are using an older version of jdk 1.4.x.