Class TagSupport
- java.lang.Object
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- jakarta.servlet.jsp.tagext.TagSupport
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- All Implemented Interfaces:
IterationTag,JspTag,Tag,java.io.Serializable
- Direct Known Subclasses:
BodyTagSupport
public class TagSupport extends java.lang.Object implements IterationTag, java.io.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 Description protected java.lang.StringidThe value of the id attribute of this tag; or null.protected PageContextpageContextThe PageContext.-
Fields inherited from interface jakarta.servlet.jsp.tagext.IterationTag
EVAL_BODY_AGAIN
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Fields inherited from interface jakarta.servlet.jsp.tagext.Tag
EVAL_BODY_INCLUDE, EVAL_PAGE, SKIP_BODY, SKIP_PAGE
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Constructor Summary
Constructors Constructor 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 Description intdoAfterBody()Default processing for a body.intdoEndTag()Default processing of the end tag returning EVAL_PAGE.intdoStartTag()Default processing of the start tag, returning SKIP_BODY.static TagfindAncestorWithClass(Tag from, java.lang.Class<?> klass)Find the instance of a given class type that is closest to a given instance.java.lang.StringgetId()The value of the id attribute of this tag; or null.TaggetParent()The Tag instance most closely enclosing this tag instance.java.lang.ObjectgetValue(java.lang.String k)Get a the value associated with a key.java.util.Enumeration<java.lang.String>getValues()Enumerate the keys for the values kept by this tag handler.voidrelease()Release state.voidremoveValue(java.lang.String k)Remove a value associated with a key.voidsetId(java.lang.String id)Set the id attribute for this tag.voidsetPageContext(PageContext pageContext)Set the page context.voidsetParent(Tag t)Set the nesting tag of this tag.voidsetValue(java.lang.String k, java.lang.Object o)Associate a value with a String key.
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Field Detail
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id
protected java.lang.String id
The value of the id attribute of this tag; or null.
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pageContext
protected transient PageContext pageContext
The PageContext.
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Method Detail
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findAncestorWithClass
public static final Tag findAncestorWithClass(Tag from, java.lang.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 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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doStartTag
public int doStartTag() throws JspExceptionDefault processing of the start tag, returning SKIP_BODY.- Specified by:
doStartTagin 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 JspExceptionDefault processing of the end tag returning EVAL_PAGE.- Specified by:
doEndTagin 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 JspExceptionDefault processing for a body.- Specified by:
doAfterBodyin 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:
releasein interfaceTag- See Also:
Tag.release()
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setParent
public void setParent(Tag t)
Set the nesting tag of this tag.- Specified by:
setParentin 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:
getParentin interfaceTag- Returns:
- the parent tag instance or null
- See Also:
Tag.getParent()
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setId
public void setId(java.lang.String id)
Set the id attribute for this tag.- Parameters:
id- The String for the id.
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getId
public java.lang.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:
setPageContextin interfaceTag- Parameters:
pageContext- The PageContext.- See Also:
Tag.setPageContext(jakarta.servlet.jsp.PageContext)
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setValue
public void setValue(java.lang.String k, java.lang.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 java.lang.Object getValue(java.lang.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(java.lang.String k)
Remove a value associated with a key.- Parameters:
k- The string key.
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getValues
public java.util.Enumeration<java.lang.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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