TagAdapter (Java EE 5)

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

包装任何 SimpleTag，并使用 Tag 接口公开它。此类用于支持经典标记处理程序与 SimpleTag 处理程序之间的协作。

因为 SimpleTag 没有扩展 Tag，并且因为 Tag.setParent() 只接受 Tag 实例，所以经典标记处理程序（实现 Tag 的经典标记处理程序）无法使 SimpleTag 成为其父标记。为了对此进行补救，可创建 TagAdapter 来包装 SimpleTag 父标记，并将适配器传递给 setParent()。经典标记处理程序可以调用 getAdaptee() 来获取已封装的 SimpleTag 实例。

since

2.0

英文文档：

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

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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

public TagAdapter(SimpleTag adaptee)
创建包装给定 SimpleTag 的新 TagAdapter，并在调用 getParent() 时返回父标记。

adaptee

将被适配为 Tag 的 SimpleTag。

英文文档：

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

public void setPageContext(PageContext pc)
不得调用。

pc	忽略。
Throws	UnsupportedOperationException: 不得调用

英文文档：

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

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public void setParent(Tag parentTag)
不得调用。此标记的父标记始终是 getAdaptee().getParent()。

parentTag	忽略。
Throws	UnsupportedOperationException: 不得调用。

英文文档：

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.

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public Tag getParent()
返回此标记的父标记，该父标记始终是 getAdaptee().getParent()。 此父标记可能是封闭 Tag（如果 getAdaptee().getParent() 实现了 Tag），也可能是封闭 Tag 的适配器（如果 getAdaptee().getParent() 没有实现 Tag）。

return

将被适配的标记的父标记。

英文文档：

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)

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public JspTag getAdaptee()
获取将被适配到 Tag 接口的标记。在 JSP 2.0 中，此标记应该是 SimpleTag 实例，但为以后规范版本中的其他种类的标记保留了空间。

return

将被适配的标记

英文文档：

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

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public int doStartTag() throws JspException
不得调用。

return	总是抛出 UnsupportedOperationException
Throws	UnsupportedOperationException: 不得调用
Throws	JspException: 不会抛出

英文文档：

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

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public int doEndTag() throws JspException
不得调用。

return	总是抛出 UnsupportedOperationException
Throws	UnsupportedOperationException: 不得调用
Throws	JspException: 不会抛出

英文文档：

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

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public void release()
不得调用。

Throws

UnsupportedOperationException: 不得调用

英文文档：

release

public void release()

Must not be called.

Specified by:

release in interface Tag

Throws:

UnsupportedOperationException - Must not be called

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