Embeddable Java Compiler
Janino is a compiler that reads a Java expression, block, class body, source file or a set of source files, and generates Java bytecode that is loaded and executed directly. Janino is not intended to be a development tool, but an embedded compiler for run-time compilation purposes, e.g. expression evaluators or "server pages" engines like JSP.
Janino can also be used for static code analysis
The project's home page is http://janino.net