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Java > Open Source Codes > org > apache > turbine > modules > layouts > VelocityOnlyLayout


1 package org.apache.turbine.modules.layouts;
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.commons.logging.Log;
20 import org.apache.commons.logging.LogFactory;
21
22 import org.apache.ecs.ConcreteElement;
23
24 import org.apache.turbine.TurbineConstants;
25 import org.apache.turbine.modules.Layout;
26 import org.apache.turbine.modules.ScreenLoader;
27 import org.apache.turbine.services.velocity.TurbineVelocity;
28 import org.apache.turbine.util.RunData;
29 import org.apache.turbine.util.template.TemplateNavigation;
30
31 import org.apache.velocity.context.Context;
32
33 /**
34  * This Layout module allows Velocity templates to be used as layouts.
35  * Since dynamic content is supposed to be primarily located in
36  * screens and navigations there should be relatively few reasons to
37  * subclass this Layout.
38  *
39  * To get the same functionality as with VelocityECSLayout, you can use two
40  * supplied VelocityMacros, TurbineHtmlHead and TurbineHtmlBodyAttributes
41  * in your templates. These are used to put HtmlPageAttributes into a page
42  * before rendering.
43  *
44  * Use these macros should be used in the Layout template like this:
45  *
46  * ... set things like style sheets, scripts here.
47  * <html>
48  * #TurbineHtmlHead()
49  * <body #TurbineHtmlBodyAttributes() >
50  * .... your body information
51  * </body>
52  * </html>
53  *
54  * As the layout template is rendered _after_ the screen template, you
55  * can of course, add information to the $page tool in your screen template.
56  * This will be added correctly to the <head>...</head> and
57  * <body> tags.
58  *
59  * @author <a HREF="mailto:john.mcnally@clearink.com">John D. McNally</a>
60  * @author <a HREF="mailto:mbryson@mont.mindspring.com">Dave Bryson</a>
61  * @author <a HREF="mailto:hps@intermeta.de">Henning P. Schmiedehausen</a>
62  * @version $Id: VelocityOnlyLayout.java,v 1.12.2.2 2004/05/20 03:03:54 seade Exp $
63  */
64 public class VelocityOnlyLayout
65     extends Layout
66 {
67     /** Logging */
68     private static Log log = LogFactory.getLog(VelocityOnlyLayout.class);
69
70     /** The prefix for lookup up layout pages */
71     private String JavaDoc prefix = TurbineConstants.LAYOUT_PREFIX + "/";
72
73     /**
74      * Build the layout. Also sets the ContentType and Locale headers
75      * of the HttpServletResponse object.
76      *
77      * @param data Turbine information.
78      * @exception Exception a generic exception.
79      */
80     public void doBuild(RunData data)
81         throws Exception JavaDoc
82     {
83         // Get the context needed by Velocity.
84 Context context = TurbineVelocity.getContext(data);
85
86         String JavaDoc screenName = data.getScreen();
87
88         log.debug("Loading Screen " + screenName);
89
90         // First, generate the screen and put it in the context so
91 // we can grab it the layout template.
92 ConcreteElement results =
93             ScreenLoader.getInstance().eval(data, screenName);
94
95         String JavaDoc returnValue = (results == null) ? "" : results.toString();
96
97         // variable for the screen in the layout template
98 context.put(TurbineConstants.SCREEN_PLACEHOLDER, returnValue);
99
100         // variable to reference the navigation screen in the layout template
101 context.put(TurbineConstants.NAVIGATION_PLACEHOLDER,
102                     new TemplateNavigation(data));
103
104         // Grab the layout template set in the VelocityPage.
105 // If null, then use the default layout template
106 // (done by the TemplateInfo object)
107 String JavaDoc templateName = data.getTemplateInfo().getLayoutTemplate();
108
109         // Set the locale and content type
110 data.getResponse().setLocale(data.getLocale());
111         data.getResponse().setContentType(data.getContentType());
112
113         log.debug("Now trying to render layout " + templateName);
114
115         // Finally, generate the layout template and send it to the browser
116 data.getOut().print(TurbineVelocity
117                 .handleRequest(context, prefix + templateName));
118     }
119 }
120
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