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  /*
   * $Id: ConverterELTag.java,v 1.8 2007/01/29 07:29:01 rlubke Exp $
   */
  
  /*
   * The contents of this file are subject to the terms
   * of the Common Development and Distribution License
   * (the License). You may not use this file except in
   * compliance with the License.
  * 
  * You can obtain a copy of the License at
  * https://javaserverfaces.dev.java.net/CDDL.html or
  * legal/CDDLv1.0.txt. 
  * See the License for the specific language governing
  * permission and limitations under the License.
  * 
  * When distributing Covered Code, include this CDDL
  * Header Notice in each file and include the License file
  * at legal/CDDLv1.0.txt.    
  * If applicable, add the following below the CDDL Header,
  * with the fields enclosed by brackets [] replaced by
  * your own identifying information:
  * "Portions Copyrighted [year] [name of copyright owner]"
  * 
  * [Name of File] [ver.__] [Date]
  * 
  * Copyright 2005 Sun Microsystems Inc. All Rights Reserved
  */
 
 package javax.faces.webapp;
 

ConverterELTag is a base class for all JSP custom actions that create and register a Converter instance on the javax.faces.component.ValueHolder associated with our most immediate surrounding instance of a tag whose implementation class is a subclass of UIComponentClassicTagBase. To avoid creating duplicate instances when a page is redisplayed, creation and registration of a javax.faces.convert.Converter occurs only if the corresponding javax.faces.component.UIComponent was created (by the owning UIComponentTag) during the execution of the current page.

This class may be used as a base class for tag instances that support specific javax.faces.convert.Converter subclasses.

Subclasses of this class must implement the createConverter() method, which creates and returns a javax.faces.convert.Converter instance. Any configuration properties that specify behavior of this javax.faces.convert.Converter must have been set by the createConverter() method. Generally, this occurs by copying corresponding attribute values on the tag instance.

This tag creates no output to the page currently being created. It is used solely for the side effect of javax.faces.convert.Converter creation.

 
 
 public abstract class ConverterELTag extends TagSupport {
 
 
     // ---------------------------------------------------------- Public Methods
 

    

Create a new instance of the specified javax.faces.convert.Converter class, and register it with the javax.faces.component.UIComponent instance associated with our most immediately surrounding UIComponentClassicTagBase instance, if the javax.faces.component.UIComponent instance was created by this execution of the containing JSP page. If the localValue of the javax.faces.component.UIComponent is a String, attempt to convert it.

Throws:
javax.servlet.jsp.JspException if a JSP error occurs
 
     public int doStartTag() throws JspException {
 
         // Locate our parent UIComponentTag
         UIComponentClassicTagBase tag =
              UIComponentClassicTagBase.getParentUIComponentClassicTagBase();
         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 ();
        }
        UIComponent component = tag.getComponentInstance();
        if (component == null) {            
            //PENDING i18n
            throw new JspException("Can't create Component from tag.");
        }
        if (!(component instanceof ValueHolder)) {
            //PENDING i18n
            throw new JspException("Not nested in a tag of proper type. Error for tag with handler class:"+
                    this.getClass().getName());
        }
        
        Converter converter = createConverter();
        
        if (converter == null) {
            throw new JspException("Can't create class of type:"+
                    " javax.faces.convert.Converter, converter is null");
        }
        
        ValueHolder vh = (ValueHolder)component;
        FacesContext context = FacesContext.getCurrentInstance();
        
        // Register an instance with the appropriate component
        vh.setConverter(converter);
        
        // Once the converter has been set, attempt to convert the
        // incoming "value"
        Object localValue = vh.getLocalValue();
        if (localValue instanceof String) {
            try {
                localValue = converter.getAsObject(context, (UIComponent)vh, (StringlocalValue);
                vh.setValue(localValue);
            }
            catch (ConverterException ce) {
                // PENDING - Ignore?  Throw an exception?  Set the local
                // value back to "null" and log a warning?
            }
        }        
  
        return ();
    }
    // ------------------------------------------------------- Protected Methods


    

Create and return a new javax.faces.convert.Converter to be registered on our surrounding javax.faces.component.UIComponent.

Throws:
javax.servlet.jsp.JspException if a new instance cannot be created
    protected abstract Converter createConverter()
        throws JspException;
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