RequestParameterMatcher


1   /*
2    * Copyright 1999-2004 The Apache Software Foundation.
3    * 
4    * Licensed under the Apache License, Version 2.0 (the "License");
5    * you may not use this file except in compliance with the License.
6    * You may obtain a copy of the License at
7    * 
8    *      http://www.apache.org/licenses/LICENSE-2.0
9    * 
10   * Unless required by applicable law or agreed to in writing, software
11   * distributed under the License is distributed on an "AS IS" BASIS,
12   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13   * See the License for the specific language governing permissions and
14   * limitations under the License.
15   */
16  package org.apache.cocoon.matching;
17  
18  import org.apache.avalon.framework.parameters.Parameters;
19  import org.apache.avalon.framework.thread.ThreadSafe;
20  import org.apache.cocoon.environment.ObjectModelHelper;
21  import org.apache.cocoon.environment.Request;
22  
23  import java.util.HashMap  ;
24  import java.util.Map  ;
25  
26  /**
27   * This class allows for matching based on a request parameter.
28   * If the specified request parameter exists, its value is retrieved for later
29   * sitemap substitution.
30   *
31   * <p><b>Example:</b></p>
32   * <pre>
33   * &lt;map:match type="request" pattern="dest"&gt;
34   *     &lt;map:redirect-to uri="{1}"/&gt;
35   * &lt;/map:match&gt;
36   * </pre>
37   *
38   * @author <a HREF="mailto:Marcus.Crafter@osa.de">Marcus Crafter</a>
39   * @author <a HREF="mailto:vgritsenko@apache.org">Vadim Gritsenko</a>
40   * @version CVS $Id: RequestParameterMatcher.java 30932 2004-07-29 17:35:38Z vgritsenko $
41   */
42  public class RequestParameterMatcher implements Matcher, ThreadSafe
43  {
44      /**
45       * Match method to see if the request parameter exists. If it does
46       * have a value the parameter is added to the array list for later
47       * sitemap substitution.
48       *
49       * @param pattern name of request parameter to find
50       * @param objectModel environment passed through via cocoon
51       * @return null or map containing value of request parameter 'pattern'
52       */
53      public Map   match(String   pattern, Map   objectModel, Parameters parameters) {
54          Request request = ObjectModelHelper.getRequest(objectModel);
55  
56          String   parameter = request.getParameter(pattern);
57          if (parameter == null) {
58              return null; // no parameter defined
59          } else {
60              Map   map = new HashMap  ();
61              map.put("1", parameter);
62              return map; // parameter defined, return map
63          }
64      }
65  }
66
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