JSL is a library written in Java that provides a framework for general searching on graphs. While the standard search algorithms depth-first, breadth-first and A* are already provided by JSL you can easily plug in any other search algorithm you like.
JSL must not be confused with libraries for full text or web search. While those create indices for fast text search JSL searches graphs that represent abstract problems described in a domain. It is thus much more related to problems found in AI.
The domain of the search can be anything you like specified by custom classes imeplementing JSL's adapter interfaces.
There does not seem to be anything really comparable to JSL, yet, but weakly related may be constraint logic programming / constraint satisfaction problem solver libraries like
JSL: Copyright (c) 2003-2004, Oliver Zeigermann, Henrik Heine