javax.servlet.jsp.tagext
Class TagSupport
java.lang.Objectjavax.servlet.jsp.tagext.TagSupport
- IterationTag, JspTag, Serializable, Tag
public class TagSupport
extends java.lang.Object
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.
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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int | doAfterBody()- Default processing for a body.
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int | doEndTag()- Default processing of the end tag returning EVAL_PAGE.
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int | doStartTag()- Default processing of the start tag, returning SKIP_BODY.
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static Tag | findAncestorWithClass(Tag from, Class klass)- Find the instance of a given class type that is closest to a given
instance.
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String | getId()- The value of the id attribute of this tag; or null.
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Tag | getParent()- The Tag instance most closely enclosing this tag instance.
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Object | getValue(String k)- Get a the value associated with a key.
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Enumeration | getValues()- Enumerate the keys for the values kept by this tag handler.
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void | release()- Release state.
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void | removeValue(String k)- Remove a value associated with a key.
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void | setId(String id)- Set the id attribute for this tag.
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void | setPageContext(PageContext pageContext)- Set the page context.
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void | setParent(Tag t)- Set the nesting tag of this tag.
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void | setValue(String k, Object o)- Associate a value with a String key.
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id
protected String id
The value of the id attribute of this tag; or null.
pageContext
protected PageContext pageContext
The PageContext.
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.
doEndTag
public int doEndTag()
throws JspException Default processing of the end tag returning EVAL_PAGE.
- doEndTag in interface Tag
doStartTag
public int doStartTag()
throws JspException Default processing of the start tag, returning SKIP_BODY.
- doStartTag in interface Tag
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.
from - The instance from where to start looking.klass - The subclass of Tag or interface to be matched
- the nearest ancestor that implements the interface
or is an instance of the class specified
getId
public String getId()
The value of the id attribute of this tag; or null.
- the value of the id attribute, or null
getParent
public Tag getParent()
The Tag instance most closely enclosing this tag instance.
- getParent in interface Tag
- the parent tag instance or null
getValue
public Object getValue(String k)
Get a the value associated with a key.
- The value associated with the key, or null.
getValues
public Enumeration getValues()
Enumerate the keys for the values kept by this tag handler.
- An enumeration of all the keys for the values set,
or null or an empty Enumeration if no values have been set.
release
public void release()
Release state.
- release in interface Tag
removeValue
public void removeValue(String k)
Remove a value associated with a key.
setId
public void setId(String id)
Set the id attribute for this tag.
id - The String for the id.
setPageContext
public void setPageContext(PageContext pageContext)
Set the page context.
- setPageContext in interface Tag
pageContext - The PageContext.
setParent
public void setParent(Tag t)
Set the nesting tag of this tag.
- setParent in interface Tag
setValue
public void setValue(String k,
Object o) Associate a value with a String key.
k - The key String.o - The value to associate.
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