I need to do full text searches on my entities, across many different fields, and with many different parameters. A while ago I heard about Hibernate Search(TM), and became envious. It took me about two days*, but it is (almost) here. Here is how I search my blog's posts at the moment:
And yes, I probably do have seamless integration with updating the indexes, so I wouldn't have to worry about it except for the first time. I strongly suggest that you would read the documentation above, since it is almost identical to my implementation.
Unlike most of my stuff, I am not going to release it just yet, it still needs more testing and some beating before I will let it see the light of day.
* And just to point out, no sleep, for real. I am working on caffiene and sheer inertation at the moment.