How do I make an search bar at the top of the page like on stackoverflow.com?

I need t开发者_如何学Co make the search bar at the top of the page like stackoverflow.com have in its website. I need some sample code for jsp/servlet for performing the operation for searching. What operation it provide while one write something at the search bar. I want to search anything but into my website only.

Please give me some idea...

Thanks

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You can use Lucene, that's a pretty good full text search engine. Since you are coding in Java it shouldn't be difficult at all to implement your search feature from Lucene.

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I believe you can use Google site search, there is more info here.

Or if you are willing to do more work you could check out the Apache Lucene project here.