001package org.apache.turbine.modules.screens;
002
003/*
004 * Licensed to the Apache Software Foundation (ASF) under one
005 * or more contributor license agreements.  See the NOTICE file
006 * distributed with this work for additional information
007 * regarding copyright ownership.  The ASF licenses this file
008 * to you under the Apache License, Version 2.0 (the
009 * "License"); you may not use this file except in compliance
010 * with the License.  You may obtain a copy of the License at
011 *
012 *   http://www.apache.org/licenses/LICENSE-2.0
013 *
014 * Unless required by applicable law or agreed to in writing,
015 * software distributed under the License is distributed on an
016 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
017 * KIND, either express or implied.  See the License for the
018 * specific language governing permissions and limitations
019 * under the License.
020 */
021
022import org.apache.commons.configuration.Configuration;
023import org.apache.commons.lang.StringUtils;
024import org.apache.commons.lang.exception.ExceptionUtils;
025import org.apache.turbine.TurbineConstants;
026import org.apache.turbine.annotation.TurbineConfiguration;
027import org.apache.turbine.annotation.TurbineService;
028import org.apache.turbine.pipeline.PipelineData;
029import org.apache.turbine.services.template.TemplateService;
030import org.apache.turbine.services.velocity.VelocityService;
031import org.apache.turbine.util.RunData;
032import org.apache.velocity.context.Context;
033
034/**
035 * Base Velocity Screen.  The buildTemplate() assumes the template
036 * parameter has been set in the PipelineData object.  This provides the
037 * ability to execute several templates from one Screen.
038 *
039 * <p>
040 *
041 * If you need more specific behavior in your application, extend this
042 * class and override the doBuildTemplate() method.
043 *
044 * @author <a href="mailto:mbryson@mont.mindspring.com">Dave Bryson</a>
045 * @author <a href="mailto:hps@intermeta.de">Henning P. Schmiedehausen</a>
046 * @author <a href="mailto:peter@courcoux.biz">Peter Courcoux</a>
047 * @version $Id: VelocityScreen.java 1709648 2015-10-20 17:08:10Z tv $
048 */
049public class VelocityScreen
050    extends TemplateScreen
051{
052    /** The prefix for lookup up screen pages */
053    private final String prefix = getPrefix() + "/";
054
055    /** Injected service instance */
056    @TurbineService
057    protected VelocityService velocity;
058
059    /** Injected service instance */
060    @TurbineService
061    protected TemplateService templateService;
062
063    /** Injected configuration instance */
064    @TurbineConfiguration
065    protected Configuration conf;
066
067    /**
068     * Velocity Screens extending this class should override this
069     * method to perform any particular business logic and add
070     * information to the context.
071     *
072     * @param pipelineData Turbine information.
073     * @param context Context for web pages.
074     * @exception Exception, a generic exception.
075     */
076    protected void doBuildTemplate(PipelineData pipelineData,
077                                   Context context)
078            throws Exception
079    {
080        // empty
081    }
082
083    /**
084     * Needs to be implemented to make TemplateScreen like us.  The
085     * actual method that you should override is the one with the
086     * context in the parameter list.
087     *
088     * @param pipelineData Turbine information.
089     * @exception Exception, a generic exception.
090     */
091    @Override
092    protected void doBuildTemplate(PipelineData pipelineData)
093            throws Exception
094    {
095        doBuildTemplate(pipelineData, velocity.getContext(pipelineData));
096    }
097
098    /**
099     * 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}