/*
 * $Id: ForwardAction.java 54929 2004-10-16 16:38:42Z germuska $ 
 *
 * Copyright 2001-2004 The Apache Software Foundation.
 * 
 * Licensed 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.struts.actions;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.struts.action.Action;
import org.apache.struts.action.ActionForm;
import org.apache.struts.action.ActionForward;
import org.apache.struts.action.ActionMapping;
import org.apache.struts.util.MessageResources;

/**
 * <p>An <strong>Action</strong> that forwards to the context-relative
 * URI specified by the <code>parameter</code> property of our associated
 * <code>ActionMapping</code>.  This can be used to integrate Struts with
 * other business logic components that are implemented as servlets (or JSP
 * pages), but still take advantage of the Struts controller servlet's
 * functionality (such as processing of form beans).</p>
 *
 * <p>To configure the use of this Action in your
 * <code>struts-config.xml</code> file, create an entry like this:</p>
 *
 * <code>
 *   &lt;action path="/saveSubscription"
 *           type="org.apache.struts.actions.ForwardAction"
 *           name="subscriptionForm"
 *          scope="request"
 *          input="/subscription.jsp"
 *      parameter="/path/to/processing/servlet"/&gt;
 * </code>
 *
 * <p>which will forward control to the context-relative URI specified by the
 * <code>parameter</code> attribute.</p>
 *
 * @version $Rev: 54929 $ $Date: 2004-10-16 17:38:42 +0100 (Sat, 16 Oct 2004) $
 */
public class ForwardAction extends Action {


    // ----------------------------------------------------- Instance Variables


    /**
     * The message resources for this package.
     */
    protected static MessageResources messages =
     MessageResources.getMessageResources
        ("org.apache.struts.actions.LocalStrings");


    // --------------------------------------------------------- Public Methods


    /**
     * Process the specified HTTP request, and create the corresponding HTTP
     * response (or forward to another web component that will create it).
     * Return an <code>ActionForward</code> instance describing where and how
     * control should be forwarded, or <code>null</code> if the response has
     * already been completed.
     *
     * @param mapping The ActionMapping used to select this instance
     * @param form The optional ActionForm bean for this request (if any)
     * @param request The HTTP request we are processing
     * @param response The HTTP response we are creating
     *
     * @exception Exception if an error occurs
     */
    public ActionForward execute(
        ActionMapping mapping,
        ActionForm form,
        HttpServletRequest request,
        HttpServletResponse response)
        throws Exception {

        // Create a RequestDispatcher the corresponding resource
        String path = mapping.getParameter();

        if (path == null) {
            throw new ServletException(messages.getMessage("forward.path"));
        }

        // Let the controller handle the request
        ActionForward retVal = new ActionForward(path);
        retVal.setContextRelative(true);

        return retVal;
    }


}