javax.servlet.jsp.jstl.core: abstract public class: ConditionalTagSupport

javax.servlet.jsp.jstl.core
abstract public class: ConditionalTagSupport [javadoc | source]

java.lang.Object
   javax.servlet.jsp.tagext.TagSupport
      javax.servlet.jsp.jstl.core.ConditionalTagSupport

All Implemented Interfaces:
IterationTag, Serializable

Abstract class that facilitates implementation of conditional actions where the boolean result is exposed as a JSP scoped variable. The boolean result may then be used as the test condition in a <c:when> action.

This base class provides support for:

Conditional processing of the action's body based on the returned value of the abstract method condition().
Storing the result of condition() as a Boolean object into a JSP scoped variable identified by attributes var and scope.

author: Shawn - Bayern

Fields inherited from javax.servlet.jsp.tagext.TagSupport:
id, pageContext

Constructor:

Constructor:
public ConditionalTagSupport() { super(); init(); } Base constructor to initialize local state. As with `TagSupport`, subclasses should not implement constructors with arguments, and no-argument constructors implemented by subclasses must call the superclass constructor.

 public ConditionalTagSupport() {
        super();
        init();
}

Base constructor to initialize local state. As with TagSupport, subclasses should not implement constructors with arguments, and no-argument constructors implemented by subclasses must call the superclass constructor.

Method from javax.servlet.jsp.jstl.core.ConditionalTagSupport Summary:
condition, doStartTag, release, setScope, setVar

Methods from javax.servlet.jsp.tagext.TagSupport:
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.jstl.core.ConditionalTagSupport Detail:
abstract protected boolean condition() throws JspTagException Subclasses implement this method to compute the boolean result of the conditional action. This method is invoked once per tag invocation by `doStartTag()`.
public int doStartTag() throws JspException { // execute our condition() method once per invocation result = condition(); // expose variables if appropriate exposeVariables(); // handle conditional behavior if (result) return EVAL_BODY_INCLUDE; else return SKIP_BODY; } Includes its body if `condition()` evaluates to true.
public void release() { super.release(); init(); } Releases any resources this ConditionalTagSupport may have (or inherit).
public void setScope(String scope) { if (scope.equalsIgnoreCase("page")) this.scope = PageContext.PAGE_SCOPE; else if (scope.equalsIgnoreCase("request")) this.scope = PageContext.REQUEST_SCOPE; else if (scope.equalsIgnoreCase("session")) this.scope = PageContext.SESSION_SCOPE; else if (scope.equalsIgnoreCase("application")) this.scope = PageContext.APPLICATION_SCOPE; // TODO: Add error handling? Needs direction from spec. } Sets the 'scope' attribute.
public void setVar(String var) { this.var = var; } Sets the 'var' attribute.

Method from javax.servlet.jsp.jstl.core.ConditionalTagSupport Detail:

 abstract protected boolean condition() throws JspTagExceptionSubclasses implement this method to compute the boolean result
of the conditional action. This method is invoked once per tag invocation 
by doStartTag().

 public int doStartTag() throws JspException {
        // execute our condition() method once per invocation
        result = condition();
        // expose variables if appropriate
        exposeVariables();
        // handle conditional behavior
        if (result)
            return EVAL_BODY_INCLUDE;
        else
            return SKIP_BODY;
}

condition()

 public  void release() {
        super.release();
        init();
}

Releases any resources this ConditionalTagSupport may have (or inherit).

 public  void setScope(String scope) {
	if (scope.equalsIgnoreCase("page"))
	    this.scope = PageContext.PAGE_SCOPE;
	else if (scope.equalsIgnoreCase("request"))
	    this.scope = PageContext.REQUEST_SCOPE;
	else if (scope.equalsIgnoreCase("session"))
	    this.scope = PageContext.SESSION_SCOPE;
	else if (scope.equalsIgnoreCase("application"))
	    this.scope = PageContext.APPLICATION_SCOPE;
	// TODO: Add error handling?  Needs direction from spec.
}

Sets the 'scope' attribute.

 public  void setVar(String var) {
	this.var = var;
}

Sets the 'var' attribute.