from http://java.sun.com/j2ee/1.4/docs/tutorial/doc/index.html | Chapter 12
| EL | Variables
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The JSP expression language unifies the treatment of the . and []
operators. expr-a.expr-b is equivalent to a["expr-b"]; that is, the
expression expr-b is used to construct a literal whose value is the
identifier, and then the [] operator is used with that value.
To evaluate expr-a[expr-b], evaluate expr-a into value-a and evaluate
expr-b into value-b. If either value-a or value-b is null, return null.
* If value-a is a Map, return value-a.get(value-b). If
!value-a.containsKey(value-b), then return null.
* If value-a is a List or array, coerce value-b to int and return
value-a.get(value-b) or Array.get(value-a, value-b), as appropriate. If the
coercion couldn't be performed, an error is returned. If the get call
returns an IndexOutOfBoundsException, null is returned. If the get call
returns another exception, an error is returned.
* If value-a is a JavaBeans object, coerce value-b to String. If
value-b is a readable property of value-a, then return the result of a get
call. If the get method throws an exception, an error is returned.
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