AttributeHandler.java :  » J2EE » facelets » com » sun » facelets » tag » jsf » core » Java Open Source

/**
 * Licensed under the Common Development and Distribution License,
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 *   http://www.sun.com/cddl/
 *   
 * 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 com.sun.facelets.tag.jsf.core;

import java.io.IOException;

import javax.el.ELException;
import javax.faces.FacesException;
import javax.faces.component.UIComponent;

import com.sun.facelets.FaceletContext;
import com.sun.facelets.FaceletException;
import com.sun.facelets.el.ELAdaptor;
import com.sun.facelets.tag.TagAttribute;
import com.sun.facelets.tag.TagConfig;
import com.sun.facelets.tag.TagException;
import com.sun.facelets.tag.TagHandler;

/**
 * Sets the specified name and attribute on the parent UIComponent. If the
 * "value" specified is not a literal, it will instead set the ValueExpression
 * on the UIComponent.
 * <p />
 * See <a target="_new"
 * href="http://java.sun.com/j2ee/javaserverfaces/1.1_01/docs/tlddocs/f/attribute.html">tag
 * documentation</a>.
 * 
 * @see javax.faces.component.UIComponent#getAttributes()
 * @see javax.faces.component.UIComponent#setValueExpression(java.lang.String,
 *      javax.el.ValueExpression)
 * @author Jacob Hookom
 * @version $Id: AttributeHandler.java,v 1.2 2005/08/24 04:38:49 jhook Exp $
 */
public final class AttributeHandler extends TagHandler {

    private final TagAttribute name;

    private final TagAttribute value;

    /**
     * @param config
     */
    public AttributeHandler(TagConfig config) {
        super(config);
        this.name = this.getRequiredAttribute("name");
        this.value = this.getRequiredAttribute("value");
    }

    /*
     * (non-Javadoc)
     * 
     * @see com.sun.facelets.FaceletHandler#apply(com.sun.facelets.FaceletContext,
     *      javax.faces.component.UIComponent)
     */
    public void apply(FaceletContext ctx, UIComponent parent)
            throws IOException, FacesException, FaceletException, ELException {
        if (parent == null) {
            throw new TagException(this.tag, "Parent UIComponent was null");
        }

        // only process if the parent is new to the tree
        if (parent.getParent() == null) {
            String n = this.name.getValue(ctx);
            if (!parent.getAttributes().containsKey(n)) {
                if (this.value.isLiteral()) {
                    parent.getAttributes().put(n, this.value.getValue());
                } else {
                    ELAdaptor.setExpression(parent, n, this.value
                            .getValueExpression(ctx, Object.class));
                }
            }
        }
    }
}