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Java > Open Source Codes > org > apache > turbine > modules > pages > TemplatePage


1 package org.apache.turbine.modules.pages;
2
3 /*
4  * Copyright 2001-2004 The Apache Software Foundation.
5  *
6  * Licensed under the Apache License, Version 2.0 (the "License")
7  * you may not use this file except in compliance with the License.
8  * You may obtain a copy of the License at
9  *
10  * http://www.apache.org/licenses/LICENSE-2.0
11  *
12  * Unless required by applicable law or agreed to in writing, software
13  * distributed under the License is distributed on an "AS IS" BASIS,
14  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
15  * See the License for the specific language governing permissions and
16  * limitations under the License.
17  */
18
19 import org.apache.turbine.services.template.TurbineTemplate;
20 import org.apache.turbine.util.RunData;
21 import org.apache.turbine.util.TurbineException;
22
23 /**
24  * When building sites using templates, Screens need only be defined
25  * for templates which require dynamic (database or object) data.
26  *
27  * <p>
28  *
29  * This page can be used on sites where the number of Screens can be
30  * much less than the number of templates. The templates can be
31  * grouped in directories with common layouts. Screen modules are
32  * then expected to be placed in packages corresponding with the
33  * templates' directories and follow a specific naming scheme.
34  *
35  * <p>
36  *
37  * The template parameter is parsed and and a Screen whose package
38  * matches the templates path and shares the same name minus any
39  * extension and beginning with a capital letter is searched for. If
40  * not found, a Screen in a package matching the template's path with
41  * name Default is searched for. If still not found, a Screen with
42  * name Default is looked for in packages corresponding to parent
43  * directories in the template's path until a match is found.
44  *
45  * <p>
46  *
47  * For example if data.getParameters().getString("template") returns
48  * /about_us/directions/driving.wm, the search follows
49  * about_us.directions.Driving, about_us.directions.Default,
50  * about_us.Default, Default, WebMacroSiteScreen (i.e. the default
51  * screen set in TurbineResources).
52  *
53  * <p>
54  *
55  * Only one Layout module is used, since it is expected that any
56  * dynamic content will be placed in navigations and screens. The
57  * layout template to be used is found in a similar way to the Screen.
58  * For example the following paths will be searched in the layouts
59  * subdirectory: /about_us/directions/driving.wm,
60  * /about_us/directions/default.wm, /about_us/default.wm, /default.wm,
61  * where wm is the value of the template.default.extension property.
62  *
63  * <p>
64  *
65  * This approach allows a site with largely static content to be
66  * updated and added to regularly by those with little Java
67  * experience.
68  *
69  * @author <a HREF="mailto:john.mcnally@clearink.com">John D. McNally</a>
70  * @author <a HREF="mailto:mbryson@mont.mindspring.com">Dave Bryson</a>
71  * @author <a HREF="mailto:hps@intermeta.de">Henning P. Schmiedehausen</a>
72  * @version $Id: TemplatePage.java,v 1.5.2.3 2004/08/14 20:11:41 henning Exp $
73  */
74 public class TemplatePage
75     extends DefaultPage
76 {
77     /**
78      * Works with TemplateService to set up default templates and
79      * corresponding class modules.
80      *
81      * @param data Turbine information.
82      * @exception Exception, a generic exception.
83      */
84     protected void doBuildAfterAction(RunData data)
85         throws Exception JavaDoc
86     {
87         // The Template Service at this point must fetch the Screen class
88 // to match a given template. If the Screen class has already been
89 // set by an action, skip this, because the user has the already
90 // specified the Screen class he wants to use.
91 if (!data.hasScreen())
92         {
93             // This is effectively getting the "template" parameter
94 // from the parameter parser in rundata. This is coming
95 // from the request for a template.
96 String JavaDoc template = data.getTemplateInfo().getScreenTemplate();
97
98             // Get the layout template and the correct Screen.
99 String JavaDoc layoutTemplate =
100                     TurbineTemplate.getLayoutTemplateName(template);
101             data.getTemplateInfo().setLayoutTemplate(layoutTemplate);
102
103             String JavaDoc screen = TurbineTemplate.getScreenName(template);
104
105             if (screen == null)
106             {
107                 String JavaDoc errMsg = "Couldn't map Template "
108                     + template + " to any Screen class!";
109                 log.error(errMsg);
110                 throw new TurbineException(errMsg);
111             }
112             data.setScreen(screen);
113         }
114     }
115 }
116
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