View Javadoc

1   package org.apache.velocity.app.event.implement;
2   
3   /*
4    * Licensed to the Apache Software Foundation (ASF) under one
5    * or more contributor license agreements.  See the NOTICE file
6    * distributed with this work for additional information
7    * regarding copyright ownership.  The ASF licenses this file
8    * to you under the Apache License, Version 2.0 (the
9    * "License"); you may not use this file except in compliance
10   * with the License.  You may obtain a copy of the License at
11   *
12   *   http://www.apache.org/licenses/LICENSE-2.0
13   *
14   * Unless required by applicable law or agreed to in writing,
15   * software distributed under the License is distributed on an
16   * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
17   * KIND, either express or implied.  See the License for the
18   * specific language governing permissions and limitations
19   * under the License.    
20   */
21  
22  import org.apache.velocity.app.event.IncludeEventHandler;
23  import org.apache.velocity.context.Context;
24  import org.apache.velocity.runtime.RuntimeServices;
25  import org.apache.velocity.util.ContextAware;
26  import org.apache.velocity.util.RuntimeServicesAware;
27  import org.apache.velocity.util.StringUtils;
28  
29  /**
30   * Simple event handler that checks to see if an included page is available.
31   * If not, it includes a designated replacement page instead.
32   *
33   * <P>By default, the name of the replacement page is "notfound.vm", however this
34   * page name can be changed by setting the Velocity property
35   * <code>eventhandler.include.notfound</code>, for example:
36   * <code>
37   * <PRE>
38   * eventhandler.include.notfound = error.vm
39   * </PRE>
40   * </code>
41   * </p><p>
42   * The name of the missing resource is put into the Velocity context, under the 
43   * key "missingResource", so that the "notfound" template can report the missing 
44   * resource with a Velocity reference, like: 
45   * <code>$missingResource</code>
46   * </p>
47   *
48   * @author <a href="mailto:wglass@forio.com">Will Glass-Husain</a>
49   * @version $Id: IncludeNotFound.java 809822 2009-09-01 05:30:56Z nbubna $
50   * @since 1.5
51   */
52  public class IncludeNotFound implements IncludeEventHandler,RuntimeServicesAware,ContextAware {
53  
54      private static final String DEFAULT_NOT_FOUND = "notfound.vm";
55      private static final String PROPERTY_NOT_FOUND = "eventhandler.include.notfound";
56      private RuntimeServices rs = null;
57      String notfound;
58      Context context;
59  
60      /**
61       * Chseck to see if included file exists, and display "not found" page if it
62       * doesn't. If "not found" page does not exist, log an error and return
63       * null.
64       * 
65       * @param includeResourcePath
66       * @param currentResourcePath
67       * @param directiveName
68       * @return message.
69       */
70      public String includeEvent(
71          String includeResourcePath,
72          String currentResourcePath,
73          String directiveName)
74      {
75  
76          /**
77           * check to see if page exists
78           */
79          boolean exists = (rs.getLoaderNameForResource(includeResourcePath) != null);
80          if (!exists)
81          {
82              context.put("missingResource", includeResourcePath);
83              if (rs.getLoaderNameForResource(notfound) != null)
84              {
85                  return notfound;
86              }
87              else
88              {
89                  /**
90                   * can't find not found, so display nothing
91                   */
92                  rs.getLog().error("Can't find include not found page: " + notfound);
93                  return null;
94              }
95          }
96          else
97              return includeResourcePath;
98      }
99  
100 
101     /**
102      * @see org.apache.velocity.util.RuntimeServicesAware#setRuntimeServices(org.apache.velocity.runtime.RuntimeServices)
103      */
104     public void setRuntimeServices(RuntimeServices rs)
105     {
106          this.rs = rs;
107          notfound = StringUtils.nullTrim(rs.getString(PROPERTY_NOT_FOUND, DEFAULT_NOT_FOUND));
108     }
109 
110     /** 
111      * @see org.apache.velocity.util.ContextAware#setContext(org.apache.velocity.context.Context)
112      */ 
113     public void setContext(Context context)
114     {
115         this.context = context;
116     }
117 }