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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.configuration.Configuration;
23  import org.apache.commons.lang.StringUtils;
24  import org.apache.commons.lang.exception.ExceptionUtils;
25  import org.apache.turbine.TurbineConstants;
26  import org.apache.turbine.annotation.TurbineConfiguration;
27  import org.apache.turbine.annotation.TurbineService;
28  import org.apache.turbine.pipeline.PipelineData;
29  import org.apache.turbine.services.template.TemplateService;
30  import org.apache.turbine.services.velocity.VelocityService;
31  import org.apache.turbine.util.RunData;
32  import org.apache.velocity.context.Context;
33  
34  /**
35   * Base Velocity Screen.  The buildTemplate() assumes the template
36   * parameter has been set in the PipelineData object.  This provides the
37   * ability to execute several templates from one Screen.
38   *
39   * <p>
40   *
41   * If you need more specific behavior in your application, extend this
42   * class and override the doBuildTemplate() method.
43   *
44   * @author <a href="mailto:mbryson@mont.mindspring.com">Dave Bryson</a>
45   * @author <a href="mailto:hps@intermeta.de">Henning P. Schmiedehausen</a>
46   * @author <a href="mailto:peter@courcoux.biz">Peter Courcoux</a>
47   * @version $Id: VelocityScreen.java 1709648 2015-10-20 17:08:10Z tv $
48   */
49  public class VelocityScreen
50      extends TemplateScreen
51  {
52      /** The prefix for lookup up screen pages */
53      private final String prefix = getPrefix() + "/";
54  
55      /** Injected service instance */
56      @TurbineService
57      protected VelocityService velocity;
58  
59      /** Injected service instance */
60      @TurbineService
61      protected TemplateService templateService;
62  
63      /** Injected configuration instance */
64      @TurbineConfiguration
65      protected Configuration conf;
66  
67      /**
68       * Velocity Screens extending this class should override this
69       * method to perform any particular business logic and add
70       * information to the context.
71       *
72       * @param pipelineData Turbine information.
73       * @param context Context for web pages.
74       * @exception Exception, a generic exception.
75       */
76      protected void doBuildTemplate(PipelineData pipelineData,
77                                     Context context)
78              throws Exception
79      {
80          // empty
81      }
82  
83      /**
84       * Needs to be implemented to make TemplateScreen like us.  The
85       * actual method that you should override is the one with the
86       * context in the parameter list.
87       *
88       * @param pipelineData Turbine information.
89       * @exception Exception, a generic exception.
90       */
91      @Override
92      protected void doBuildTemplate(PipelineData pipelineData)
93              throws Exception
94      {
95          doBuildTemplate(pipelineData, velocity.getContext(pipelineData));
96      }
97  
98      /**
99       * This builds the Velocity template.
100      *
101      * @param pipelineData Turbine information.
102      * @return the content of the screen
103      * @exception Exception, a generic exception.
104      */
105     @Override
106     public String buildTemplate(PipelineData pipelineData)
107         throws Exception
108     {
109         RunData data = getRunData(pipelineData);
110         String screenData = null;
111 
112         Context context = velocity.getContext(pipelineData);
113 
114         String screenTemplate = data.getTemplateInfo().getScreenTemplate();
115         String templateName
116             = templateService.getScreenTemplateName(screenTemplate);
117 
118         // The Template Service could not find the Screen
119         if (StringUtils.isEmpty(templateName))
120         {
121             log.error("Screen " + screenTemplate + " not found!");
122             throw new Exception("Could not find screen for " + screenTemplate);
123         }
124 
125         try
126         {
127             // if a layout has been defined return the results, otherwise
128             // send the results directly to the output stream.
129             if (getLayout(pipelineData) == null)
130             {
131                 velocity.handleRequest(context,
132                         prefix + templateName,
133                         data.getResponse().getOutputStream());
134             }
135             else
136             {
137                 screenData =
138                     velocity.handleRequest(context, prefix + templateName);
139             }
140         }
141         catch (Exception e)
142         {
143             // If there is an error, build a $processingException and
144             // attempt to call the error.vm template in the screens
145             // directory.
146             context.put (TurbineConstants.PROCESSING_EXCEPTION_PLACEHOLDER, e.toString());
147             context.put (TurbineConstants.STACK_TRACE_PLACEHOLDER, ExceptionUtils.getStackTrace(e));
148 
149             templateName = conf.getString(TurbineConstants.TEMPLATE_ERROR_KEY,
150                            TurbineConstants.TEMPLATE_ERROR_VM);
151 
152             screenData = velocity.handleRequest(context, prefix + templateName);
153         }
154 
155         return screenData;
156     }
157 }