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.lang3.StringUtils;
023import org.apache.commons.lang3.exception.ExceptionUtils;
024import org.apache.turbine.TurbineConstants;
025import org.apache.turbine.annotation.TurbineConfiguration;
026import org.apache.turbine.annotation.TurbineService;
027import org.apache.turbine.pipeline.PipelineData;
028import org.apache.turbine.services.template.TemplateService;
029import org.apache.turbine.services.velocity.VelocityService;
030import org.apache.turbine.util.RunData;
031import org.apache.velocity.context.Context;
032
033/**
034 * Base Velocity Screen.  The buildTemplate() assumes the template
035 * parameter has been set in the PipelineData object.  This provides the
036 * ability to execute several templates from one Screen.
037 *
038 * <p>
039 *
040 * If you need more specific behavior in your application, extend this
041 * class and override the doBuildTemplate() method.
042 *
043 * @author <a href="mailto:mbryson@mont.mindspring.com">Dave Bryson</a>
044 * @author <a href="mailto:hps@intermeta.de">Henning P. Schmiedehausen</a>
045 * @author <a href="mailto:peter@courcoux.biz">Peter Courcoux</a>
046 * @version $Id$
047 */
048public class VelocityScreen
049    extends TemplateScreen
050{
051    /** The prefix for lookup up screen pages */
052    protected static final String prefix = PREFIX + "/";
053
054    /** Injected service instance */
055    @TurbineService
056    protected VelocityService velocity;
057
058    /** Injected service instance */
059    @TurbineService
060    protected TemplateService templateService;
061
062    @TurbineConfiguration( TurbineConstants.TEMPLATE_ERROR_KEY )
063    protected String templateError = TurbineConstants.TEMPLATE_ERROR_VM;
064
065    /**
066     * Velocity Screens extending this class should override this
067     * method to perform any particular business logic and add
068     * information to the context.
069     *
070     * @param pipelineData Turbine information.
071     * @param context Context for web pages.
072     * @throws Exception a generic exception.
073     */
074    protected void doBuildTemplate(PipelineData pipelineData,
075                                   Context context)
076            throws Exception
077    {
078        // empty
079    }
080
081    /**
082     * Needs to be implemented to make TemplateScreen like us.  The
083     * actual method that you should override is the one with the
084     * context in the parameter list.
085     *
086     * @param pipelineData Turbine information.
087     * @throws Exception a generic exception.
088     */
089    @Override
090    protected void doBuildTemplate(PipelineData pipelineData)
091            throws Exception
092    {
093        doBuildTemplate(pipelineData, velocity.getContext(pipelineData));
094    }
095
096    /**
097     * This builds the Velocity template.
098     *
099     * @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}