Chapter 16. Simplifying Access to Java Code: The JSP 2.0 Expression Language

Topics in This Chapter

Motivating use of the expression language
Invoking the expression language
Disabling the expression language
Preventing the use of classic scripting elements
Understanding the relationship of the expression language to the MVC architecture
Referencing scoped variables
Accessing bean properties, array elements, List elements, and Map entries
Using expression language operators
Evaluating expressions conditionally

JSP 2.0 introduced a shorthand language for evaluating and outputting the values of Java objects that are stored in standard locations. This expression language (EL) is one of the two most important new features of JSP 2.0; the other is the ability to define custom tags with JSP syntax instead of Java syntax. This chapter discusses the expression language; Volume 2 discusses the new tag library capabilities.

Core Warning

The JSP expression language cannot be used in servers that support only JSP 1.2 or earlier.