TagAdapter (Java EE 5 SDK)

javax.servlet.jsp.tagext Class TagAdapter

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

所有已实现的接口:

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.

从以下版本开始:

JSP 2.0

TagAdapter

public TagAdapter(SimpleTag adaptee)

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

参数:

adaptee - The SimpleTag being adapted as a Tag.

setPageContext

public void setPageContext(PageContext pc)

Must not be called.

规范说明:

setPageContext in interface Tag

参数:

pc - ignored.

抛出异常:

UnsupportedOperationException - Must not be called

setParent

public void setParent(Tag parentTag)

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

规范说明:

setParent in interface Tag

参数:

parentTag - ignored.

抛出异常:

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).

规范说明:

getParent in interface Tag

返回:

The parent of the tag being adapted.

另请参见:

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.

返回:

the tag that is being adapted

doStartTag

public int doStartTag()
               throws JspException

Must not be called.

规范说明:

doStartTag in interface Tag

返回:

always throws UnsupportedOperationException

抛出异常:

UnsupportedOperationException - Must not be called

JspException - never thrown

另请参见:

BodyTag

doEndTag

public int doEndTag()
             throws JspException

Must not be called.

规范说明:

doEndTag in interface Tag

返回:

always throws UnsupportedOperationException

抛出异常:

UnsupportedOperationException - Must not be called

JspException - never thrown

release

public void release()

Must not be called.

规范说明:

release in interface Tag

抛出异常:

UnsupportedOperationException - Must not be called

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