/*
    * $Id$
    *
    * 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.struts.dispatcher.servlet;
  
  import org.apache.struts.chain.contexts.ActionContext;
  import org.apache.struts.chain.contexts.ServletActionContext;
  import org.apache.struts.dispatcher.AbstractParameterDispatcher;
  
  import jakarta.servlet.http.HttpServletResponse;
  
  /**
   * This servlet-based dispatcher uses the value of the request parameter to pick
   * the appropriate method on the action.
   * <p>
   * To configure the use of this dispatcher in your configuration, create an
   * entry like below:
   * <p>
   * <code>
   * <pre>
   * &lt;action path=&quot;/saveSubscription&quot;
   *         type=&quot;org.example.SubscriptionAction&quot;
   *         dispatcher=&quot;org.apache.struts.dispatcher.servlet.ServletParameterDispatcher&quot;
   *         parameter=&quot;method&quot;/&gt;
   *         name=&quot;subscriptionForm&quot;
   *         scope=&quot;request&quot;
   *         input=&quot;/subscription.jsp&quot;
   * </pre>
   * </code>
   * <p>
   * This example will use the value of the request parameter named "method" to
   * pick the appropriate method. For example, you might have the following three
   * methods in the same action:
   *
   * <ul>
   * <li><code>public ActionForward delete(ActionMapping mapping, ActionForm form,
   * HttpServletRequest request, HttpServletResponse response) throws Exception</code></li>
   * <li><code>public void insert(ActionContext context)</code></li>
   * <li><code>public void update(ServletActionContext context)</code></li>
   * </ul>
   * and call one of the methods with a URL like this:
   * <p>
   * <code>http://localhost:8080/myapp/saveSubscription.do?method=update</code>
   *
   * @version $Rev$
   * @since Struts 1.4
   */
  public class ServletParameterDispatcher extends AbstractParameterDispatcher {
  
      private static final long serialVersionUID = 1L;
  
      /**
       * Constructs a new servlet parameter dispatcher.
       */
      public ServletParameterDispatcher() {
          super(new ServletMethodResolver());
      }
  
      /**
       * Extracts the value from the specified servlet parameter.
       *
       * @param context {@inheritDoc}
       * @param parameter the servlet parameter name
       * @return the servlet parameter value
       */
      protected String resolveParameterValue(ActionContext context, String parameter) {
          ServletActionContext servletContext = (ServletActionContext) context;
          return servletContext.getParam().get(parameter);
      }
  
      /**
       * Sends the 404 HTTP error response.
       *
       * @param context {@inheritDoc}
       * @return always <code>null</code> since the response is handled directly
       * @throws Exception if the error code fails to set
       */
      protected Object unspecified(ActionContext context) throws Exception {
          HttpServletResponse response = ((ServletActionContext) context).getResponse();
          response.sendError(HttpServletResponse.SC_NOT_FOUND);
          return null;
      }
 
 }