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Java > Open Source Codes > org > apache > turbine > modules > screens > VelocityDirectScreen


1 package org.apache.turbine.modules.screens;
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.lang.StringUtils;
20 import org.apache.commons.lang.exception.ExceptionUtils;
21
22 import org.apache.ecs.ConcreteElement;
23
24 import org.apache.velocity.context.Context;
25
26 import org.apache.turbine.Turbine;
27 import org.apache.turbine.TurbineConstants;
28 import org.apache.turbine.services.template.TurbineTemplate;
29 import org.apache.turbine.services.velocity.TurbineVelocity;
30 import org.apache.turbine.util.RunData;
31
32 /**
33  * VelocityDirectScreen is a screen class which returns its output
34  * directly to the output stream. It can be used if buffering an
35  * output screen isn't possible or the result doesn't fit in the
36  * memory.
37  * <p>
38  * @author <a HREF="mailto:mbryson@mont.mindspring.com">Dave Bryson</a>
39  * @author <a HREF="mailto:hps@intermeta.de">Henning P. Schmiedehausen</a>
40  * @version $Id: VelocityDirectScreen.java,v 1.11.2.3 2004/08/14 20:11:41 henning Exp $
41  */
42 public class VelocityDirectScreen
43     extends VelocityScreen
44 {
45     /** The prefix for lookup up screen pages */
46     private String JavaDoc prefix = TurbineConstants.SCREEN_PREFIX + "/";
47
48     /**
49      * This builds the Velocity template.
50      *
51      * @param data Turbine information.
52      * @return A ConcreteElement.
53      * @exception Exception, a generic exception.
54      */
55     public ConcreteElement buildTemplate(RunData data)
56         throws Exception JavaDoc
57     {
58         Context context = TurbineVelocity.getContext(data);
59
60         String JavaDoc screenTemplate = data.getTemplateInfo().getScreenTemplate();
61         String JavaDoc templateName
62             = TurbineTemplate.getScreenTemplateName(screenTemplate);
63
64         // The Template Service could not find the Screen
65 if (StringUtils.isEmpty(templateName))
66         {
67             log.error("Screen " + screenTemplate + " not found!");
68             throw new Exception JavaDoc("Could not find screen for " + screenTemplate);
69         }
70
71         try
72         {
73             TurbineVelocity.handleRequest(context,
74                                           prefix + templateName,
75                                           data.getOut());
76
77         }
78         catch (Exception JavaDoc e)
79         {
80             // If there is an error, build a $processingException and
81 // attempt to call the error.vm template in the screens
82 // directory.
83 context.put (TurbineConstants.PROCESSING_EXCEPTION_PLACEHOLDER, e.toString());
84             context.put (TurbineConstants.STACK_TRACE_PLACEHOLDER, ExceptionUtils.getStackTrace(e));
85
86             templateName = Turbine.getConfiguration()
87                 .getString(TurbineConstants.TEMPLATE_ERROR_KEY,
88                            TurbineConstants.TEMPLATE_ERROR_VM);
89
90             TurbineVelocity.handleRequest(context,
91                     prefix + templateName,
92                     data.getOut());
93         }
94
95         return null;
96     }
97 }
98
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