Expression Languages

Jakarta JXPath
JXPath defines a simple interpreter of an expression language called XPath. JXPath applies XPath expressions to graphs of objects of called XPath. JXPath applies XPath expressions to graphs of objects of all kinds: JavaBeans, Maps, Servlet contexts, DOM etc, including mixtures thereof.

Java Expression Language - JEXL
Java Expression Language (JEXL) is an expression language engine which can be embedded in applications and frameworks. JEXL is inspired which can be embedded in applications and frameworks. JEXL is inspired by Jakarta Velocity and the Expression Language defined in the JavaServer Pages Standard Tag Library version 1.1 (JSTL) and JavaServer Pages version 2.0 (JSP). While inspired by JSTL EL, it must be noted that JEXL is not a compatible implementation of EL as defined in JSTL 1.1 (JSR-052) or JSP 2.0 (JSR-152)

Object Graph Navigation Language - OGNL
OGNL stands for Object-Graph Navigation Language; it is an expression language for getting and setting properties of Java objects. expression language for getting and setting properties of Java objects. You use the same expression for both getting and setting the value of a property. The ognl.Ognl class contains convenience methods for evaluating OGNL expressions. You can do this in two stages, parsing an expression into an internal form and then using that internal form to either set or get the value of a property; or you can do it in a single stage, and get or set a property using the String form of the expression directly.

MVEL
MVEL is a powerful expression language for Java-based applications. It provides a plethora of features and is suited for applications. It provides a plethora of features and is suited for everything from the smallest property binding and extraction, to full blown scripts. MVEL is general purpose. It may be useful as an extension to anything from use in JSP Tag Libraries, to the configuration facilities of your library/framework. In addition to being an expression language, MVEL also comes packaged with an equally high-performance templating system similar to Velocity and FreeMarker.

JUEL
JUEL (Java Unified Expression Language) provides a lightweight and efficient implementation of the unified expression language (EL) as and efficient implementation of the unified expression language (EL) as specified by the JSP 2.1 standard. Though still part of JSP, the EL API has been separated into package javax.el and all dependencies to the core JSP classes have been removed.

JExel
JExel is a Java based expression language. It is a non-compiled scripting language parser that can be useful in many different scripting language parser that can be useful in many different applications. It can handle most basic mathematical and string expressions with the built in operator set fairly easily.