1 package org.apache.turbine.modules.screens;
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.commons.lang3.StringUtils;
23 import org.apache.commons.lang3.exception.ExceptionUtils;
24 import org.apache.turbine.TurbineConstants;
25 import org.apache.turbine.annotation.TurbineConfiguration;
26 import org.apache.turbine.annotation.TurbineService;
27 import org.apache.turbine.pipeline.PipelineData;
28 import org.apache.turbine.services.template.TemplateService;
29 import org.apache.turbine.services.velocity.VelocityService;
30 import org.apache.turbine.util.RunData;
31 import org.apache.velocity.context.Context;
32
33 /**
34 * Base Velocity Screen. The buildTemplate() assumes the template
35 * parameter has been set in the PipelineData object. This provides the
36 * ability to execute several templates from one Screen.
37 *
38 * <p>
39 *
40 * If you need more specific behavior in your application, extend this
41 * class and override the doBuildTemplate() method.
42 *
43 * @author <a href="mailto:mbryson@mont.mindspring.com">Dave Bryson</a>
44 * @author <a href="mailto:hps@intermeta.de">Henning P. Schmiedehausen</a>
45 * @author <a href="mailto:peter@courcoux.biz">Peter Courcoux</a>
46 * @version $Id$
47 */
48 public class VelocityScreen
49 extends TemplateScreen
50 {
51 /** The prefix for lookup up screen pages */
52 protected static final String prefix = PREFIX + "/";
53
54 /** Injected service instance */
55 @TurbineService
56 protected VelocityService velocity;
57
58 /** Injected service instance */
59 @TurbineService
60 protected TemplateService templateService;
61
62 @TurbineConfiguration( TurbineConstants.TEMPLATE_ERROR_KEY )
63 protected String templateError = TurbineConstants.TEMPLATE_ERROR_VM;
64
65 /**
66 * Velocity Screens extending this class should override this
67 * method to perform any particular business logic and add
68 * information to the context.
69 *
70 * @param pipelineData Turbine information.
71 * @param context Context for web pages.
72 * @throws Exception a generic exception.
73 */
74 protected void doBuildTemplate(PipelineData pipelineData,
75 Context context)
76 throws Exception
77 {
78 // empty
79 }
80
81 /**
82 * Needs to be implemented to make TemplateScreen like us. The
83 * actual method that you should override is the one with the
84 * context in the parameter list.
85 *
86 * @param pipelineData Turbine information.
87 * @throws Exception a generic exception.
88 */
89 @Override
90 protected void doBuildTemplate(PipelineData pipelineData)
91 throws Exception
92 {
93 doBuildTemplate(pipelineData, velocity.getContext(pipelineData));
94 }
95
96 /**
97 * This builds the Velocity template.
98 *
99 * @param pipelineData Turbine information.
100 * @return the content of the screen
101 * @throws Exception a generic exception.
102 */
103 @Override
104 public String buildTemplate(PipelineData pipelineData)
105 throws Exception
106 {
107 RunData data = pipelineData.getRunData();
108 String screenData = null;
109
110 Context context = velocity.getContext(pipelineData);
111
112 String screenTemplate = data.getTemplateInfo().getScreenTemplate();
113 String templateName
114 = templateService.getScreenTemplateName(screenTemplate);
115
116 // The Template Service could not find the Screen
117 if (StringUtils.isEmpty(templateName))
118 {
119 log.error("Screen " + screenTemplate + " not found!");
120 throw new Exception("Could not find screen for " + screenTemplate);
121 }
122
123 try
124 {
125 // if a layout has been defined return the results, otherwise
126 // send the results directly to the output stream.
127 if (getLayout(pipelineData) == null)
128 {
129 velocity.handleRequest(context,
130 prefix + templateName,
131 data.getResponse().getOutputStream());
132 }
133 else
134 {
135 screenData =
136 velocity.handleRequest(context, prefix + templateName);
137 }
138 }
139 catch (Exception e)
140 {
141 // If there is an error, build a $processingException and
142 // attempt to call the error.vm template in the screens
143 // directory.
144 context.put (TurbineConstants.PROCESSING_EXCEPTION_PLACEHOLDER, e.toString());
145 context.put (TurbineConstants.STACK_TRACE_PLACEHOLDER, ExceptionUtils.getStackTrace(e));
146
147 screenData = velocity.handleRequest(context, prefix + templateError);
148 }
149
150 return screenData;
151 }
152 }