Description:

OGNL stands for Object-Graph Navigation Language; it is an
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.
Many people have asked exactly what OGNL is good for. Several
of the uses to which OGNL has been applied are:
* A binding language between GUI elements (textfield, combobox,
etc.) to model objects. Transformations are made easier by
OGNL's TypeConverter mechanism to convert values from one
type to another (String to numeric types, for example).
* A data source language to map between table columns and a
TableModel.
* A binding language between web components and the underlying
model objects (WebOGNL, Tapestry and WebWork).
* A more expressive replacement for the property-getting
language used by the Jakarta Commons BeanUtils package
(which only allows simple property navigation and
rudimentary indexed properties).
Most of what you can do in Java is possible in OGNL, plus other
extras such as list projection and selection and lambda expressions.