Home » apache-tomcat-6.0.26-src » javax » servlet » jsp » tagext » [javadoc | source]

javax.servlet.jsp.tagext
public class: TagSupport [javadoc | source]

java.lang.Object
   javax.servlet.jsp.tagext.TagSupport

All Implemented Interfaces:
    IterationTag, Serializable

Direct Known Subclasses:
    LoopTagSupport, ConditionalTagSupport, BodyTagSupport

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.

Field Summary
protected  String	id	The value of the id attribute of this tag; or null.
protected  PageContext	pageContext	The PageContext.

Constructor:
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.

Method from javax.servlet.jsp.tagext.TagSupport Summary:
doAfterBody,   doEndTag,   doStartTag,   findAncestorWithClass,   getId,   getParent,   getValue,   getValues,   release,   removeValue,   setId,   setPageContext,   setParent,   setValue

Methods from java.lang.Object:
clone,   equals,   finalize,   getClass,   hashCode,   notify,   notifyAll,   toString,   wait,   wait,   wait

Method from javax.servlet.jsp.tagext.TagSupport Detail:
public int doAfterBody() throws JspException { return SKIP_BODY; } Default processing for a body.
public int doEndTag() throws JspException { return EVAL_PAGE; } Default processing of the end tag returning EVAL_PAGE.
public int doStartTag() throws JspException { return SKIP_BODY; } Default processing of the start tag, returning SKIP_BODY.
public static final Tag findAncestorWithClass(Tag from, Class klass) { boolean isInterface = false; if (from == null || klass == null || (!Tag.class.isAssignableFrom(klass) && !(isInterface = klass.isInterface()))) { return null; } for (;;) { Tag tag = from.getParent(); if (tag == null) { return null; } if ((isInterface && klass.isInstance(tag)) || klass.isAssignableFrom(tag.getClass())) return tag; else from = tag; } } 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.
public String getId() { return id; } The value of the id attribute of this tag; or null.
public Tag getParent() { return parent; } The Tag instance most closely enclosing this tag instance.
public Object getValue(String k) { if (values == null) { return null; } else { return values.get(k); } } Get a the value associated with a key.
public Enumeration<String> getValues() { if (values == null) { return null; } return values.keys(); } Enumerate the keys for the values kept by this tag handler.
public void release() { parent = null; id = null; if( values != null ) { values.clear(); } values = null; } Release state.
public void removeValue(String k) { if (values != null) { values.remove(k); } } Remove a value associated with a key.
public void setId(String id) { this.id = id; } Set the id attribute for this tag.
public void setPageContext(PageContext pageContext) { this.pageContext = pageContext; } Set the page context.
public void setParent(Tag t) { parent = t; } Set the nesting tag of this tag.
public void setValue(String k, Object o) { if (values == null) { values = new Hashtable< String, Object >(); } values.put(k, o); } Associate a value with a String key.