javax.servlet.jsp.tagext
Class TagAdapter

java.lang.Object
  javax.servlet.jsp.tagext.TagAdapter

All Implemented Interfaces:

JspTag, Tag

public class TagAdapter
extends Object
implements Tag

Wraps any SimpleTag and exposes it using a Tag interface. This is used to allow collaboration between classic Tag handlers and SimpleTag handlers.

Because SimpleTag does not extend Tag, and because Tag.setParent() only accepts a Tag instance, a classic tag handler (one that implements Tag) cannot have a SimpleTag as its parent. To remedy this, a TagAdapter is created to wrap the SimpleTag parent, and the adapter is passed to setParent() instead. A classic Tag Handler can call getAdaptee() to retrieve the encapsulated SimpleTag instance.

Since:

JSP 2.0

Field Summary

Fields inherited from interface javax.servlet.jsp.tagext.Tag

EVAL_BODY_INCLUDE, EVAL_PAGE, SKIP_BODY, SKIP_PAGE

Constructor Summary

TagAdapter(SimpleTag adaptee)
Creates a new TagAdapter that wraps the given SimpleTag and returns the parent tag when getParent() is called.

Method Summary

int	doEndTag() Must not be called.
int	doStartTag() Must not be called.
JspTag	getAdaptee() Gets the tag that is being adapted to the Tag interface.
Tag	getParent() Returns the parent of this tag, which is always getAdaptee().getParent().
void	release() Must not be called.
void	setPageContext(PageContext pc) Must not be called.
void	setParent(Tag parentTag) Must not be called.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

TagAdapter

public TagAdapter(SimpleTag adaptee)

Creates a new TagAdapter that wraps the given SimpleTag and returns the parent tag when getParent() is called.

Parameters:

adaptee - The SimpleTag being adapted as a Tag.

Method Detail

setPageContext

public void setPageContext(PageContext pc)

Must not be called.

Specified by:

setPageContext in interface Tag

Parameters:

pc - ignored.

Throws:

UnsupportedOperationException - Must not be called

setParent

public void setParent(Tag parentTag)

Must not be called. The parent of this tag is always getAdaptee().getParent().

Specified by:

setParent in interface Tag

Parameters:

parentTag - ignored.

Throws:

UnsupportedOperationException - Must not be called.

getParent

public Tag getParent()

Returns the parent of this tag, which is always getAdaptee().getParent(). This will either be the enclosing Tag (if getAdaptee().getParent() implements Tag), or an adapter to the enclosing Tag (if getAdaptee().getParent() does not implement Tag).

Specified by:

getParent in interface Tag

Returns:

The parent of the tag being adapted.

See Also:

TagSupport.findAncestorWithClass(javax.servlet.jsp.tagext.Tag, java.lang.Class)

getAdaptee

public JspTag getAdaptee()

Gets the tag that is being adapted to the Tag interface. This should be an instance of SimpleTag in JSP 2.0, but room is left for other kinds of tags in future spec versions.

Returns:

the tag that is being adapted

doStartTag

public int doStartTag()
               throws JspException

Must not be called.

Specified by:

doStartTag in interface Tag

Returns:

always throws UnsupportedOperationException

Throws:

UnsupportedOperationException - Must not be called

JspException - never thrown

See Also:

BodyTag

doEndTag

public int doEndTag()
             throws JspException

Must not be called.

Specified by:

doEndTag in interface Tag

Returns:

always throws UnsupportedOperationException

Throws:

UnsupportedOperationException - Must not be called

JspException - never thrown

release

public void release()

Must not be called.

Specified by:

release in interface Tag

Throws:

UnsupportedOperationException - Must not be called