Class TagSupport
- All Implemented Interfaces:
- IterationTag,- JspTag,- Tag,- Serializable
- Direct Known Subclasses:
- BodyTagSupport
The TagSupport class is a utility class intended to be used as the base class for new tag handlers. The TagSupport class implements the Tag and IterationTag interfaces and adds additional convenience methods including getter methods for the properties in Tag. TagSupport has one static method that is included to facilitate coordination among cooperating tags.
Many tag handlers will extend TagSupport and only redefine a few methods.
- See Also:
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Field SummaryFieldsModifier and TypeFieldDescriptionprotected StringThe value of the id attribute of this tag; or null.protected PageContextThe PageContext.Fields inherited from interface jakarta.servlet.jsp.tagext.IterationTagEVAL_BODY_AGAINFields inherited from interface jakarta.servlet.jsp.tagext.TagEVAL_BODY_INCLUDE, EVAL_PAGE, SKIP_BODY, SKIP_PAGE
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Constructor SummaryConstructorsConstructorDescriptionDefault constructor, all subclasses are required to define only a public constructor with the same signature, and to call the superclass constructor.
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Method SummaryModifier and TypeMethodDescriptionintDefault processing for a body.intdoEndTag()Default processing of the end tag returning EVAL_PAGE.intDefault processing of the start tag, returning SKIP_BODY.static final TagfindAncestorWithClass(Tag from, Class<?> klass) Find the instance of a given class type that is closest to a given instance.getId()The value of the id attribute of this tag; or null.The Tag instance most closely enclosing this tag instance.Get a the value associated with a key.Enumerate the keys for the values kept by this tag handler.voidrelease()Release state.voidRemove a value associated with a key.voidSet the id attribute for this tag.voidsetPageContext(PageContext pageContext) Set the page context.voidSet the nesting tag of this tag.voidAssociate a value with a String key.
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Field Details- 
idThe value of the id attribute of this tag; or null.
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pageContextThe PageContext.
 
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Constructor Details- 
TagSupportpublic TagSupport()Default constructor, all subclasses are required to define only a public constructor with the same signature, and to call the superclass constructor. This constructor is called by the code generated by the JSP translator.
 
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Method Details- 
findAncestorWithClassFind the instance of a given class type that is closest to a given instance. This method uses the getParent method from the Tag interface. This method is used for coordination among cooperating tags.The current version of the specification only provides one formal way of indicating the observable type of a tag handler: its tag handler implementation class, described in the tag-class subelement of the tag element. This is extended in an informal manner by allowing the tag library author to indicate in the description subelement an observable type. The type should be a subtype of the tag handler implementation class or void. This additional constraint can be exploited by a specialized container that knows about that specific tag library, as in the case of the JSP standard tag library. When a tag library author provides information on the observable type of a tag handler, client programmatic code should adhere to that constraint. Specifically, the Class passed to findAncestorWithClass should be a subtype of the observable type. - Parameters:
- from- The instance from where to start looking.
- klass- The subclass of Tag or interface to be matched
- Returns:
- the nearest ancestor that implements the interface or is an instance of the class specified
 
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doStartTagDefault processing of the start tag, returning SKIP_BODY.- Specified by:
- doStartTagin interface- Tag
- Returns:
- SKIP_BODY
- Throws:
- JspException- if an error occurs while processing this tag
- See Also:
 
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doEndTagDefault processing of the end tag returning EVAL_PAGE.- Specified by:
- doEndTagin interface- Tag
- Returns:
- EVAL_PAGE
- Throws:
- JspException- if an error occurs while processing this tag
- See Also:
 
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doAfterBodyDefault processing for a body.- Specified by:
- doAfterBodyin interface- IterationTag
- Returns:
- SKIP_BODY
- Throws:
- JspException- if an error occurs while processing this tag
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releasepublic void release()Release state.
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setParentSet the nesting tag of this tag.
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getParentThe Tag instance most closely enclosing this tag instance.
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setIdSet the id attribute for this tag.- Parameters:
- id- The String for the id.
 
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getIdThe value of the id attribute of this tag; or null.- Returns:
- the value of the id attribute, or null
 
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setPageContextSet the page context.- Specified by:
- setPageContextin interface- Tag
- Parameters:
- pageContext- The PageContext.
- See Also:
 
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setValueAssociate a value with a String key.- Parameters:
- k- The key String.
- o- The value to associate.
 
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getValueGet a the value associated with a key.- Parameters:
- k- The string key.
- Returns:
- The value associated with the key, or null.
 
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removeValueRemove a value associated with a key.- Parameters:
- k- The string key.
 
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getValuesEnumerate the keys for the values kept by this tag handler.- Returns:
- An enumeration of all the keys for the values set, or null or an empty Enumeration if no values have been set.
 
 
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