/*
* $Id: ValidatorELTag.java,v 1.5 2007/04/27 22:00:12 ofung Exp $
*/
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package javax.faces.webapp;
import javax.faces.component.EditableValueHolder;
import javax.faces.component.UIComponent;
import javax.faces.validator.Validator;
import javax.servlet.jsp.JspException;
import javax.servlet.jsp.tagext.TagSupport;
/**
* <p><strong>ValidatorELTag</strong> is a base class for all JSP custom actions
* that create and register a <code>Validator</code> instance on the
* {@link EditableValueHolder} associated with our most immediate surrounding instance
* of a tag whose implementation class is a subclass of {@link UIComponentTag}.
* To avoid creating duplicate instances when a page is redisplayed,
* creation and registration of a {@link Validator} occurs
* <strong>only</strong> if the corresponding {@link UIComponent} was
* created (by the owning {@link UIComponentTagBase}) during the execution of the
* current page.</p>
*
* <p>This class must be used as a base class for tag instances that
* support specific {@link Validator} subclasses.</p>
*
* <p>Subclasses of this class must implement the
* <code>createValidator()</code> method, which creates and returns a
* {@link Validator} instance. Any configuration properties that specify
* the limits to be enforced by this {@link Validator} must have been
* set by the <code>createValidator()</code> method. Generally, this occurs
* by copying corresponding attribute values on the tag instance.</p>
*
* <p>This tag creates no output to the page currently being created. It
* is used solely for the side effect of {@link Validator} creation.</p>
*
*/
public abstract class ValidatorELTag extends TagSupport {
// --------------------------------------------------------- Public Methods
/**
* <p>Create a new instance of the specified {@link Validator}
* class, and register it with the {@link UIComponent} instance associated
* with our most immediately surrounding {@link UIComponentTagBase} instance, if
* the {@link UIComponent} instance was created by this execution of the
* containing JSP page.</p>
*
* @throws JspException if a JSP error occurs
*/
public int doStartTag() throws JspException {
// Locate our parent UIComponentTag
UIComponentClassicTagBase tag =
UIComponentClassicTagBase.getParentUIComponentClassicTagBase(pageContext);
if (tag == null) {
//PENDING i18n
throw new JspException("Not nested in a UIComponentTag Error for tag with handler class:"+
this.getClass().getName());
}
// Nothing to do unless this tag created a component
if (!tag.getCreated()) {
return (SKIP_BODY);
}
UIComponent component = tag.getComponentInstance();
if (component == null) {
//PENDING i18n
throw new JspException("Can't create Component from tag.");
}
if (!(component instanceof EditableValueHolder)) {
// PENDING i18n
throw new JspException("Not nested in a tag of proper type. Error for tag with handler class:"+
this.getClass().getName());
}
Validator validator = createValidator();
if (validator == null) {
// PENDING i18n
throw new JspException("Can't create class of type:"+
" javax.faces.validator.Validator. Validator is null");
}
// Register an instance with the appropriate component
((EditableValueHolder)component).addValidator(validator);
return (SKIP_BODY);
}
// ------------------------------------------------------ Protected Methods
/**
* <p>Create and return a new {@link Validator} to be registered
* on our surrounding {@link UIComponent}.</p>
*
* @throws JspException if a new instance cannot be created
*/
protected abstract Validator createValidator()
throws JspException;
}