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The private implementation classes of the Apache MyFaces Core JSF-2.0 Implementation
There is a newer version: 4.1.0-RC2
/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */
package org.apache.myfaces.view.facelets.tag.jsf;

import java.io.IOException;

import javax.el.ELException;
import javax.el.ValueExpression;
import javax.faces.FacesException;
import javax.faces.component.UIComponent;
import javax.faces.component.ValueHolder;
import javax.faces.context.FacesContext;
import javax.faces.convert.Converter;
import javax.faces.view.facelets.ConverterConfig;
import javax.faces.view.facelets.FaceletContext;
import javax.faces.view.facelets.FaceletException;
import javax.faces.view.facelets.MetaRuleset;
import javax.faces.view.facelets.TagAttribute;
import javax.faces.view.facelets.TagConfig;
import javax.faces.view.facelets.TagException;

import org.apache.myfaces.view.facelets.tag.MetaTagHandlerImpl;

/**
 * Handles setting a Converter instance on a ValueHolder. Will wire all attributes set to the Converter instance
 * created/fetched. Uses the "binding" attribute for grabbing instances to apply attributes to.  Will only
 * set/create Converter is the passed UIComponent's parent is null, signifying that it wasn't restored from an existing
 * tree.
 * 
 * @deprecated use javax.faces.view.facelets.ConverterHandler instead
 * @see javax.faces.webapp.ConverterELTag
 * @see javax.faces.convert.Converter
 * @see javax.faces.component.ValueHolder
 * @author Jacob Hookom
 * @version $Id: ConvertHandler.java,v 1.4 2008/07/13 19:01:46 rlubke Exp $
 */
@Deprecated
public class ConvertHandler extends MetaTagHandlerImpl
{

    private final TagAttribute binding;

    private String converterId;

    /**
     * @param config
     * @deprecated
     */
    public ConvertHandler(TagConfig config)
    {
        super(config);
        this.binding = this.getAttribute("binding");
        this.converterId = null;
    }

    public ConvertHandler(ConverterConfig config)
    {
        this((TagConfig) config);
        this.converterId = config.getConverterId();
    }

    /**
     * Set Converter instance on parent ValueHolder if it's not being restored.
     * 

     * Cast to ValueHolder
     * If "binding" attribute was specified, fetch/create and re-bind to expression.
     * Otherwise, call {@link #createConverter(FaceletContext) createConverter}.
     * Call {@link ObjectHandler#setAttributes(FaceletContext, Object) setAttributes} on Converter instance.
     * Set the Converter on the ValueHolder
     * If the ValueHolder has a localValue, convert it and set the value
     * 
     * 
     * @see ValueHolder
     * @see Converter
     * @see #createConverter(FaceletContext)
     * @see javax.faces.view.facelets.FaceletHandler#apply(javax.faces.view.facelets.FaceletContext, javax.faces.component.UIComponent)
     */
    public final void apply(FaceletContext ctx, UIComponent parent) throws IOException, FacesException,
            FaceletException, ELException
    {
        if (parent == null || !(parent instanceof ValueHolder))
        {
            throw new TagException(this.tag, "Parent not an instance of ValueHolder: " + parent);
        }

        // only process if it's been created
        if (parent.getParent() == null)
        {
            // cast to a ValueHolder
            ValueHolder vh = (ValueHolder) parent;
            ValueExpression ve = null;
            Converter c = null;
            if (this.binding != null)
            {
                ve = this.binding.getValueExpression(ctx, Converter.class);
                c = (Converter) ve.getValue(ctx);
            }
            if (c == null)
            {
                c = this.createConverter(ctx);
                if (ve != null)
                {
                    ve.setValue(ctx, c);
                }
            }
            if (c == null)
            {
                throw new TagException(this.tag, "No Converter was created");
            }
            this.setAttributes(ctx, c);
            vh.setConverter(c);
            Object lv = vh.getLocalValue();
            FacesContext faces = ctx.getFacesContext();
            if (lv instanceof String)
            {
                vh.setValue(c.getAsObject(faces, parent, (String) lv));
            }
        }
    }

    /**
     * Create a Converter instance
     * 
     * @param ctx
     *            FaceletContext to use
     * @return Converter instance, cannot be null
     */
    protected Converter createConverter(FaceletContext ctx)
    {
        if (this.converterId == null)
        {
            throw new TagException(
                                   this.tag,
                                   "Default behavior invoked of requiring a converter-id passed in the constructor, must override ConvertHandler(ConverterConfig)");
        }
        return ctx.getFacesContext().getApplication().createConverter(this.converterId);
    }

    protected MetaRuleset createMetaRuleset(Class type)
    {
        return super.createMetaRuleset(type).ignore("binding");
    }
}