When creating and evaluating expressions, some other important classes come into play: a javax.el.ELContext is required at creation time and evaluation time. It contains methods to access a function mapper (javax.el.FunctionMapper), a variable mapper (javax.el.VariableMapper) and a resolver (javax.el.ELResolver).
- At creation time, the context's function mapper and variable mapper are used to bind function invocations to static methods and identifiers (variables) to value expressions. The context's resolver is not used at creation time.
- At evaluation time, the context's resolver is used for property resolutions and to resolve unbound identifiers (top-level properties). The context's function mapper and variable mapper are not used at evaluation time.
JUEL provides simple implementations of these classes to get you using the unified EL "out of the box".