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package org.apache.taglibs.standard.tag.el.core;
import javax.servlet.jsp.JspException;
import javax.servlet.jsp.JspTagException;
import javax.servlet.jsp.jstl.core.ConditionalTagSupport;
import org.apache.taglibs.standard.lang.support.ExpressionEvaluatorManager;
import org.apache.taglibs.standard.tag.common.core.NullAttributeException;
/**
* Tag handler for <if> in JSTL's expression-evaluating library.
* Because of the support provided by the ConditionalTagSupport class,
* thistag is trivial enough not to require a separate base supporting
* class common to both libraries.
*
* @author Shawn Bayern
*/
public class IfTag extends ConditionalTagSupport {
//*********************************************************************
// Constructor and lifecycle management
// initialize inherited and local state
public IfTag() {
super();
init();
}
// Releases any resources we may have (or inherit)
public void release() {
super.release();
init();
}
//*********************************************************************
// Supplied conditional logic
protected boolean condition() throws JspTagException {
try {
Object r = ExpressionEvaluatorManager.evaluate(
"test", test, Boolean.class, this, pageContext);
if (r == null)
throw new NullAttributeException("if", "test");
else
return (((Boolean) r).booleanValue());
} catch (JspException ex) {
throw new JspTagException(ex.toString(), ex);
}
}
//*********************************************************************
// Private state
private String test; // the value of the 'test' attribute
//*********************************************************************
// Accessors
// receives the tag's 'test' attribute
public void setTest(String test) {
this.test = test;
}
//*********************************************************************
// Private utility methods
// resets internal state
private void init() {
test = null;
}
}