javax.servlet.jsp.tagext

## Class TagAdapter

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

- All Implemented Interfaces:
    JspTag, Tag

      public class TagAdapter
      extends java.lang.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:
    2.0

- - ### Field Summary

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

      `EVAL_BODY_INCLUDE, EVAL_PAGE, SKIP_BODY, SKIP_PAGE`

  - ### Constructor Summary

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

  - ### Method Summary

    Methods
    Modifier and Type | Method and Description
    --- | ---
    `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:
        `java.lang.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:
        `java.lang.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:
        `java.lang.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:
        `java.lang.UnsupportedOperationException` - Must not be called
        `JspException` - never thrown

    - #### release

          public void release()

      Must not be called.
      Specified by:
        `release` in interface `Tag`
      Throws:
        `java.lang.UnsupportedOperationException` - Must not be called

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