Class ConditionalTagSupport

  • All Implemented Interfaces:
    IterationTag, JspTag, Tag, Serializable

    public abstract class ConditionalTagSupport
    extends TagSupport

    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
    See Also:
    Serialized Form
    • Constructor Detail

      • ConditionalTagSupport

        public ConditionalTagSupport()
        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 Detail

      • condition

        protected abstract 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().

        Returns:
        a boolean representing the condition that a particular subclass uses to drive its conditional logic.
        Throws:
        JspTagException - on failure
      • release

        public void release()
        Releases any resources this ConditionalTagSupport may have (or inherit).
        Specified by:
        release in interface Tag
        Overrides:
        release in class TagSupport
        See Also:
        Tag.release()
      • setVar

        public void setVar​(String var)
        Sets the 'var' attribute.
        Parameters:
        var - Name of the exported scoped variable storing the result of condition().
      • setScope

        public void setScope​(String scope)
        Sets the 'scope' attribute.
        Parameters:
        scope - Scope of the 'var' attribute