javax.servlet.jsp.tagext

Class TagSupport

java.lang.Object

javax.servlet.jsp.tagext.TagSupport

All Implemented Interfaces:

java.io.Serializable, IterationTag, JspTag, Tag

Direct Known Subclasses:

BodyTagSupport, BundleTag, CatchTag, ChooseTag, ConditionalTagSupport, CoreRedirectTag, CoreUrlTag, CoreWhenTag, FmtRequestEncodingTag, FmtSetTimeZoneTag, FmtTimeZoneTag, FmtTimeZoneTag, ForEachTag, I18NSupport, IfTag, IfTag, IntegerLoopSupportTag, IteratorLoopSupportTag, LoopTagSupport, OtherwiseTag, RedirectTag, RemoveTag, RequestEncodingTag, SetBundleTag, SetLocaleTag, SetTimeZoneTag, SqlDateParamTag, SqlDateParamTag, SqlSetDataSourceTag, SqlSetDataSourceTag, SqlTransactionTag, SqlTransactionTag, UrlTag, WhenTag, XmlForEachTag, XmlIfTag, XmlOutTag, XmlOutTag, XmlSetTag, XmlWhenTag

public class TagSupport
extends java.lang.Object
implements IterationTag, java.io.Serializable

Convenient support class for creating tags which don't analyze their bodies. Normally, tags will extend TagSupport instead of implementing Tag directly.

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
protected java.lang.String	id The value of the "id" attribute for the tag, if specified.
protected PageContext	pageContext The owning PageContext.

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

EVAL_BODY_AGAIN

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

EVAL_BODY_INCLUDE, EVAL_PAGE, SKIP_BODY, SKIP_PAGE

Constructor Summary

Constructors

Constructor and Description
TagSupport() Tags need to implement a zero-arg constructor.

Method Summary

Modifier and Type	Method and Description
int	doAfterBody() Processed to check if the tag should loop.
int	doEndTag() Processed at the end of the tag.
int	doStartTag() Processed at the beginning of the tag.
static Tag	findAncestorWithClass(Tag tag, java.lang.Class cl) Finds an ancestor of a tag matching the class.
java.lang.String	getId() Sets the id attribute.
Tag	getParent() Returns the tag's parent.
java.lang.Object	getValue(java.lang.String name) Returns an attribute from the tag.
java.util.Enumeration<java.lang.String>	getValues() Enumerates the tag's attributes.
void	release() Cleans the tag after it completes.
void	removeValue(java.lang.String name) Removes a value from the tag.
void	setId(java.lang.String id) Sets the id attribute.
void	setPageContext(PageContext page) Stores the page context for the JSP page.
void	setParent(Tag parent) If the tag is contained in another tag, this sets the parent.
void	setValue(java.lang.String name, java.lang.Object value) Sets the value for a tag attribute.

Methods inherited from class java.lang.Object

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

Field Detail

id

protected java.lang.String id

The value of the "id" attribute for the tag, if specified.

pageContext

protected PageContext pageContext

The owning PageContext.

Constructor Detail

TagSupport

public TagSupport()

Tags need to implement a zero-arg constructor.

Method Detail

doStartTag

public int doStartTag()
               throws JspException

Processed at the beginning of the tag.

The default behavior returns SKIP_BODY to skip the tag's body.

Specified by:

doStartTag in interface Tag

Returns:

SKIP_BODY to ignore the body and EVAL_BODY_INCLUDE to evaluate the body.

Throws:

JspException

doAfterBody

public int doAfterBody()
                throws JspException

Processed to check if the tag should loop. The default behavior returns SKIP_BODY so it does not loop.

Specified by:

doAfterBody in interface IterationTag

Returns:

EVAL_BODY_AGAIN to repeat the body or SKIP_BODY to stop.

Throws:

JspException

doEndTag

public int doEndTag()
             throws JspException

Processed at the end of the tag. The default behavior continues with the rest of the JSP.

Specified by:

doEndTag in interface Tag

Returns:

EVAL_PAGE to continue the page SKIP_PAGE to stop.

Throws:

JspException

setId

public void setId(java.lang.String id)

Sets the id attribute.

getId

public java.lang.String getId()

Sets the id attribute.

setPageContext

public void setPageContext(PageContext page)

Stores the page context for the JSP page.

Specified by:

setPageContext in interface Tag

setParent

public void setParent(Tag parent)

If the tag is contained in another tag, this sets the parent.

Specified by:

setParent in interface Tag

Parameters:

parent - the tag to be used as a parent.

getParent

public Tag getParent()

Returns the tag's parent.

Specified by:

getParent in interface Tag

findAncestorWithClass

public static final Tag findAncestorWithClass(Tag tag,
                                              java.lang.Class cl)

Finds an ancestor of a tag matching the class. The search is strict, i.e. only parents will be searched, not the tag itself.

Parameters:

tag - child tag to start searching.

cl - the class that the tag should implement.

Returns:

the matching tag or null.

getValue

public java.lang.Object getValue(java.lang.String name)

Returns an attribute from the tag.

getValues

public java.util.Enumeration<java.lang.String> getValues()

Enumerates the tag's attributes.

removeValue

public void removeValue(java.lang.String name)

Removes a value from the tag.

setValue

public void setValue(java.lang.String name,
                     java.lang.Object value)

Sets the value for a tag attribute.

Parameters:

name - the name of the attribute.

value - the new value for the attribute.

release

public void release()

Cleans the tag after it completes.

Specified by:

release in interface Tag