12.2 Identify the tag library descriptor element names
that declare the following:
- The name of a tag attribute -
- Whether a tag attribute is required -
- Whether or not the attribute's value can be dynamically
specified -
12.3 Given a custom tag, identify the necessary value
for the bodycontent TLD element for any of the following
tag types:
- Empty-tag - empty
- Custom tag that surrounds other JSP code - JSP (default,
even if there-s no body-content element)
- Custom tag that surrounds content that is used only
by the tag handler - tagdependent
12.4 Given a tag event method (doStartTag, doAfterBody,
and doEndTag), identify the correct description of the methods
trigger.
- doStart - Process the start tag for this instance
- doAfterBody - Process body (re)evaluation - repeat
for iteration tag.
- doEndTag - Process the end tag for this instance.
Used to clean up resources and add any closing tags
to the output as necessary
12.5 Identify valid return values for the following
methods:
doStartTag - Tag.EVAL_BODY_INCLUDE,'
BodyTag.EVAL_BODY_BUFFERED,
Tag.SKIP_BODY
doAfterBody - IterationTag.EVAL_BODY_AGAIN, Tag.SKIP_BODY
doEndTag - Tag.EVAL_PAGE, Tag.SKIP_PAGE
PageContext.getOut - javax.servlet.jsp.JspWriter
12.6 Given a "BODY" or "PAGE" constant, identify a
correct description of the constant's use in the following
methods:
- doStartTag
- doAfterBody
- doEndTag
EVAL_BODY_AGAIN : Request the reevaluation of some body.
Returned from doAfterBody. For backward compatibility with
JSP 1.1, the value is carefully selected to be the same
as, now deprecated, BodyTag.EVAL_BODY_TAG. Defined in IterationTag.
EVAL_BODY_TAG : Deprecated now. Defined in BodyTag
EVAL_BODY_BUFFERED : Request the creation of new buffer,
a BodyContent on which to evaluate the body of this tag.
Returned from doStartTag when it implements BodyTag. This
is an illegal return value for doStartTag when the class
does not implement BodyTag. Defined in BodyTag.
EVAL_BODY_INCLUDE : Evaluate body into existing out stream.
Valid return value for doStartTag. Defined in Tag.
SKIP_BODY : Skip body evaluation. Valid return value
for doStartTag and doAfterBody. Defined in Tag.
EVAL_PAGE : Continue evaluating the page. Valid return
value for doEndTag(). Defined in Tag.
SKIP_PAGE : Skip the rest of the page. Valid return value
for doEndTag. Defined in Tag.
|
doStart |
doAfterBody |
doEndTag |
EVAL_BODY_INCLUDE |
All |
|
|
EVAL_BODY_BUFFERED |
Body tag only |
|
|
EVAL_BODY_AGAIN |
|
Iteration |
|
SKIP_BODY |
All |
All |
|
EVAL_BODY_TAG |
deprecated |
deprecated |
deprecated |
EVAL_PAGE |
|
|
All |
SKIP_PAGE |
|
|
All |
12.7 Identify the method in the custom tag handler
that accesses:
- A given JSP page's implicit variable
- The JSP page's attributes
A PageContext instance provides access to all the namespaces
associated with a JSP page, provides access to several page
attributes, as well as a layer above the implementation
details.
The following methods provide convenient access to implicit
objects:
getOut(), getException(), getPage() getRequest(), getResponse(),
getSession(),getServletConfig() and getServletContext().
The following methods provide support for forwarding,
inclusion and error handling:
forward(), include(), and handlePageException().
The methods related to attributes are:
setAttribute(), getAttribute(), removeAttribute() - deals
page scope
findAttribute(), - looks in all scopes
int getAttributesScope() and getAttributeNamesInScope(int
scope)
Note: TagSupport implements IterationTag which extends
Tag. BodyTagSupport implements BodyTag which extends IterationTag.
getPreviousOut(), getBodyContent(), setBodyContent(),
doInitBody() methods are defined in BodyTagSupport.
12.8 Identify methods that return an outer tag handler
from within an inner tag handler.
Tag Tag.getParent()
Tag TagSupport.getParent()
Tag TagSupport.findAncestorWithClass(Tag from, java.lang.Class
class) (A static method)
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