Category Archives: Java

Using a servlet filter for 404 error-page

The upcoming Wicket 1.3 and 2.0 versions intercept their requests using a servlet filter to provide more flexible resource mapping and nicer URLs. Your Wicket pages no longer need to live at foo.com/app/PageName and can instead be rooted properly at foo.com/PageName.

This is now working well. I did, however, come up against a small issue, which is how you serve custom error pages for your 404 or 500 responses. It’s nice to render these like any other pages, so you can use your branding and whatnot. This used to work fine with Wicket as a servlet, but switching to a filter broke things. I did some digging around before reading the servlet spec in more detail and finally realising you need a Servlet 2.4 spec container and web.xml config file, with some <dispatcher> elements in your filter mapping.
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More on boilerplate and IoC

Java has lately been seriously annoying me in this regard. Why do I have to write getters/setters for beans? Why can’t we just have a property keyword instead that does it automatically? Why does everyone insist on using getters/setters in the first place rather than public fields anyway? What’s the point? Ah, yes, we need to be able to proxy the methods through cglib for Hibernate, or via Spring’s IoC/AOP stuff, so we can write “better” code with fewer dependencies.
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Java boilerplate

I fixed a Wicket bug today for compressing whitespace in HTML. The wrinkle is that you need to avoid doing that inside <pre> tags, otherwise your code formatting goes all wrong.

You should probably just gzip your responses instead, as it’ll be much more efficient than this, but apparently, someone cares enough to raise a bug report, so I rolled up my sleeves. I mean, how hard can it be to strip out some whitespace?

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