OSDecoratorMapper


1   /*
2    * Title:        OSDecoratorMapper
3    * Description:
4    *
5    * This software is published under the terms of the OpenSymphony Software
6    * License version 1.1, of which a copy has been included with this
7    * distribution in the LICENSE.txt file.
8    */
9   
10  package com.opensymphony.module.sitemesh.mapper;
11  
12  import com.opensymphony.module.sitemesh.mapper.AbstractDecoratorMapper;
13  import com.opensymphony.module.sitemesh.Page;
14  import com.opensymphony.module.sitemesh.Decorator;
15  import com.opensymphony.module.sitemesh.DecoratorMapper;
16  import com.opensymphony.module.sitemesh.Config;
17  
18  import javax.servlet.http.HttpServletRequest  ;
19  import java.util.Properties  ;
20  import java.util.Enumeration  ;
21  import java.lang.String  ;
22  
23  /**
24   * The OSDecoratorMapper will map a suitable decorator based on the operating system
25   * of the remote client.
26   *
27   * <p>OSDecoratorMapper works by checking to see if the "UA-OS" header
28   * was sent with the HTTP request. If it was, the class will check the
29   * value of the header with all the different os's the user has configured
30   * the Decorator Mapper to identify and, if a match is found, routes the
31   * request accordingly.  Configuration is done using the sitemesh.xml file.
32   * The param name is a string literal (operating system name) you would like
33   * to match in the UA-OS header, and the value is what will be appended to the
34   * decorator name if the user is using that operating system</p>
35   *
36   * @author  <a HREF="mailto:schepdawg@yahoo.com">Adam P. Schepis</a>
37   * @version $Revision: 1.2 $
38   *
39   * @see com.opensymphony.module.sitemesh.mapper.AbstractDecoratorMapper
40   */
41  public final class OSDecoratorMapper extends AbstractDecoratorMapper {
42      /**
43       * Properties holds the parameters that the object was initialized with.
44       */
45      protected Properties   properties;
46  
47      /**
48       * Init initializes the OSDecoratorMapper object by setting the parent
49       * DecoratorMapper, and loading the initialization properties.
50       *
51       * @param config    The config file
52       * @param properties    An object containing intialization parameters
53       * @param parent    The parent DecoratorMapper object
54       */
55      public void init(Config config, Properties   properties, DecoratorMapper parent) throws java.lang.InstantiationException   {
56          this.properties = properties;
57          this.parent = parent;
58      }
59  
60      /**
61       * Attempts to find the correct decorator for Page page based on
62       * the UA-OS HTTP header in the request.
63       *
64       * @param request The HTTP request sent to the server
65       * @param page The page SiteMesh is trying to find a decorator for
66       *
67       * @return A Decorator object that is either the decorator for the identified
68       * OS, or the parent DecoratorMapper's decorator
69       */
70      public Decorator getDecorator(HttpServletRequest   request, Page page) {
71          String   osHeader = request.getHeader("UA-OS").toLowerCase();
72          if (osHeader == null) return parent.getDecorator(request, page);
73  
74          // run through the list of operating systems the application developer listed
75          // in sitemesh.xml to see if we have a match to the user's current OS
76          for (Enumeration   e = properties.propertyNames(); e.hasMoreElements();) {
77              String   os = (String  ) e.nextElement();
78  
79              // see if the name matches the user's operating system name
80              if (osHeader.indexOf(os.toLowerCase()) != -1) {
81                  String   decoratorName = parent.getDecorator(request, page).getName();
82                  if (decoratorName != null) {
83                      decoratorName += '-' + properties.getProperty(os);
84                  }
85                  return getNamedDecorator(request, decoratorName);
86              }
87          }
88  
89          return parent.getDecorator(request, page);
90      }
91  }
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