| The IterationTag interface extends Tag by defining one additional
method that controls the reevaluation of its body.
A tag handler that implements IterationTag is treated as one that
implements Tag regarding the doStartTag() and doEndTag() methods.
IterationTag provides a new method: doAfterBody().
The doAfterBody() method is invoked after every body evaluation
to control whether the body will be reevaluated or not. If doAfterBody()
returns IterationTag.EVAL_BODY_AGAIN, then the body will be reevaluated.
If doAfterBody() returns Tag.SKIP_BODY, then the body will be skipped
and doEndTag() will be evaluated instead.
Properties
There are no new properties in addition to those in Tag.
Methods
There is one new methods: doAfterBody().
Lifecycle
Lifecycle details are described by the transition diagram
below. Exceptions that are thrown during the computation of
doStartTag(), BODY and doAfterBody() interrupt the execution
sequence and are propagated up the stack, unless the tag handler
implements the TryCatchFinally interface; see that interface for
details.
Empty and Non-Empty Action
If the TagLibraryDescriptor file indicates that the action must
always have an empty element body, by a <body-content> entry of
"empty", then the doStartTag() method must return SKIP_BODY.
Note that which methods are invoked after the doStartTag() depends on
both the return value and on if the custom action element is empty
or not in the JSP page, not on how it's declared in the TLD.
If SKIP_BODY is returned the body is not evaluated, and then doEndTag()
is invoked.
If EVAL_BODY_INCLUDE is returned, and the custom action element is not
empty, the body is evaluated and "passed through" to the current out,
then doAfterBody() is invoked and, after zero or more iterations,
doEndTag() is invoked. | 