ActionListenerMethodTagHandler.java

/*
 * (C) Copyright 2006-2010 Nuxeo SAS (http://nuxeo.com/) and contributors.
 *
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the GNU Lesser General Public License
 * (LGPL) version 2.1 which accompanies this distribution, and is available at
 * http://www.gnu.org/licenses/lgpl.html
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * Lesser General Public License for more details.
 *
 * Contributors:
 *     <a href="mailto:at@nuxeo.com">Anahide Tchertchian</a>
 *
 * $Id$
 */

package org.nuxeo.ecm.platform.ui.web.tag.handler;

import java.io.IOException;

import javax.el.ELException;
import javax.faces.FacesException;
import javax.faces.component.ActionSource;
import javax.faces.component.UIComponent;
import javax.faces.event.ActionEvent;
import javax.faces.event.ActionListener;
import javax.faces.event.MethodExpressionActionListener;
import javax.faces.view.facelets.FaceletContext;
import javax.faces.view.facelets.FaceletException;
import javax.faces.view.facelets.TagAttribute;
import javax.faces.view.facelets.TagConfig;
import javax.faces.view.facelets.TagException;
import javax.faces.view.facelets.TagHandler;

import org.nuxeo.ecm.platform.ui.web.binding.MetaMethodExpression;

/**
 * Action listener method handler: makes it possible to add an action listener
 * method to any action source component parent.
 * <p>
 * This is useful when declaring several action listeners on the same parent
 * component, and when the order of calls needs to be respected: the action
 * listener method declared on a component is the first one called. So this
 * method makes it possible to add other action listeners before it, without
 * having to declare a class (when using the f:actionListener tag).
 *
 * @author Anahide Tchertchian
 */
public class ActionListenerMethodTagHandler extends TagHandler {

    protected final TagAttribute value;

    @SuppressWarnings("rawtypes")
    public static final Class[] ACTION_LISTENER_SIG = { ActionEvent.class };

    public ActionListenerMethodTagHandler(TagConfig config) {
        super(config);
        value = getRequiredAttribute("value");
    }

    public void apply(FaceletContext ctx, UIComponent parent)
            throws IOException, FacesException, FaceletException, ELException {
        if (parent instanceof ActionSource) {
            // only process if parent was just created
            if (parent.getParent() == null) {
                ActionSource src = (ActionSource) parent;
                ActionListener listener = new MethodExpressionActionListener(
                        new MetaMethodExpression(value.getMethodExpression(ctx,
                                null, ACTION_LISTENER_SIG)));
                src.addActionListener(listener);
            }
        } else {
            throw new TagException(tag,
                    "Parent is not of type ActionSource, type is: " + parent);
        }
    }

}