- java.lang.Object
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- javax.servlet.jsp.tagext.TagSupport
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- All Implemented Interfaces:
- Serializable, IterationTag, JspTag, Tag
- Direct Known Subclasses:
- AttributeTag, BodyTagSupport, ConditionalTagSupport, ConverterELTag, ConverterTag, FacetTag, LoopTagSupport, ValidatorELTag, ValidatorTag
public class TagSupport extends Object implements IterationTag, Serializable
A base class for defining new tag handlers implementing Tag.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:
- Serialized Form
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Field Summary
Fields Modifier and Type Field and Description protected String
id
The value of the id attribute of this tag; or null.protected PageContext
pageContext
The PageContext.-
Fields inherited from interface javax.servlet.jsp.tagext.IterationTag
EVAL_BODY_AGAIN
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Fields inherited from interface javax.servlet.jsp.tagext.Tag
EVAL_BODY_INCLUDE, EVAL_PAGE, SKIP_BODY, SKIP_PAGE
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Constructor Summary
Constructors Constructor and Description TagSupport()
Default 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 Summary
All Methods Static Methods Instance Methods Concrete Methods Modifier and Type Method and Description int
doAfterBody()
Default processing for a body.int
doEndTag()
Default processing of the end tag returning EVAL_PAGE.int
doStartTag()
Default processing of the start tag, returning SKIP_BODY.static Tag
findAncestorWithClass(Tag from, Class klass)
Find the instance of a given class type that is closest to a given instance.String
getId()
The value of the id attribute of this tag; or null.Tag
getParent()
The Tag instance most closely enclosing this tag instance.Object
getValue(String k)
Get a the value associated with a key.Enumeration<String>
getValues()
Enumerate the keys for the values kept by this tag handler.void
release()
Release state.void
removeValue(String k)
Remove a value associated with a key.void
setId(String id)
Set the id attribute for this tag.void
setPageContext(PageContext pageContext)
Set the page context.void
setParent(Tag t)
Set the nesting tag of this tag.void
setValue(String k, Object o)
Associate a value with a String key.
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Field Detail
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id
protected String id
The value of the id attribute of this tag; or null.
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pageContext
protected PageContext pageContext
The PageContext.
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Constructor Detail
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TagSupport
public 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 Detail
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findAncestorWithClass
public static final Tag findAncestorWithClass(Tag from, Class klass)
Find 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 addititional 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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doStartTag
public int doStartTag() throws JspException
Default processing of the start tag, returning SKIP_BODY.- Specified by:
doStartTag
in interfaceTag
- Returns:
- SKIP_BODY
- Throws:
JspException
- if an error occurs while processing this tag- See Also:
Tag.doStartTag()
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doEndTag
public int doEndTag() throws JspException
Default processing of the end tag returning EVAL_PAGE.- Specified by:
doEndTag
in interfaceTag
- Returns:
- EVAL_PAGE
- Throws:
JspException
- if an error occurs while processing this tag- See Also:
Tag.doEndTag()
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doAfterBody
public int doAfterBody() throws JspException
Default processing for a body.- Specified by:
doAfterBody
in interfaceIterationTag
- Returns:
- SKIP_BODY
- Throws:
JspException
- if an error occurs while processing this tag- See Also:
IterationTag.doAfterBody()
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release
public void release()
Release state.- Specified by:
release
in interfaceTag
- See Also:
Tag.release()
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setParent
public void setParent(Tag t)
Set the nesting tag of this tag.- Specified by:
setParent
in interfaceTag
- Parameters:
t
- The parent Tag.- See Also:
Tag.setParent(Tag)
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getParent
public Tag getParent()
The Tag instance most closely enclosing this tag instance.- Specified by:
getParent
in interfaceTag
- Returns:
- the parent tag instance or null
- See Also:
Tag.getParent()
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setId
public void setId(String id)
Set the id attribute for this tag.- Parameters:
id
- The String for the id.
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getId
public String getId()
The value of the id attribute of this tag; or null.- Returns:
- the value of the id attribute, or null
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setPageContext
public void setPageContext(PageContext pageContext)
Set the page context.- Specified by:
setPageContext
in interfaceTag
- Parameters:
pageContext
- The PageContext.- See Also:
Tag.setPageContext(javax.servlet.jsp.PageContext)
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setValue
public void setValue(String k, Object o)
Associate a value with a String key.- Parameters:
k
- The key String.o
- The value to associate.
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getValue
public Object getValue(String k)
Get 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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removeValue
public void removeValue(String k)
Remove a value associated with a key.- Parameters:
k
- The string key.
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getValues
public Enumeration<String> getValues()
Enumerate 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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Document créé le 24/12/2007, dernière modification le 18/08/2025
Source du document imprimé : https://www.gaudry.be/java-api-javaee-rf-javax/servlet/jsp/tagext/tagsupport.html
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