001 package org.apache.turbine.services.velocity;
002
003
004 /*
005 * Licensed to the Apache Software Foundation (ASF) under one
006 * or more contributor license agreements. See the NOTICE file
007 * distributed with this work for additional information
008 * regarding copyright ownership. The ASF licenses this file
009 * to you under the Apache License, Version 2.0 (the
010 * "License"); you may not use this file except in compliance
011 * with the License. You may obtain a copy of the License at
012 *
013 * http://www.apache.org/licenses/LICENSE-2.0
014 *
015 * Unless required by applicable law or agreed to in writing,
016 * software distributed under the License is distributed on an
017 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
018 * KIND, either express or implied. See the License for the
019 * specific language governing permissions and limitations
020 * under the License.
021 */
022
023
024 import java.io.OutputStream;
025 import java.io.Writer;
026
027 import org.apache.turbine.pipeline.PipelineData;
028 import org.apache.turbine.services.TurbineServices;
029 import org.apache.turbine.util.RunData;
030
031 import org.apache.velocity.context.Context;
032
033 /**
034 * This is a simple static accessor to common Velocity tasks such as
035 * getting an instance of a context as well as handling a request for
036 * processing a template.
037 * <pre>
038 * Context context = TurbineVelocity.getContext(data);
039 * context.put("message", "Hello from Turbine!");
040 * String results = TurbineVelocity.handleRequest(context, "helloWorld.vm");
041 * data.getPage().getBody().addElement(results);
042 * </pre>
043 *
044 * @author <a href="mailto:john.mcnally@clearink.com">John D. McNally</a>
045 * @author <a href="mailto:jon@latchkey.com">Jon S. Stevens</a>
046 * @author <a href="mailto:jvanzyl@periapt.com.com">Jason van Zyl</a>
047 * @author <a href="mailto:peter@courcoux.biz">Peter Courcoux</a>
048 * @version $Id: TurbineVelocity.java 615328 2008-01-25 20:25:05Z tv $
049 */
050 public abstract class TurbineVelocity
051 {
052 /**
053 * Utility method for accessing the service
054 * implementation
055 *
056 * @return a VelocityService implementation instance
057 */
058 public static VelocityService getService()
059 {
060 return (VelocityService) TurbineServices
061 .getInstance().getService(VelocityService.SERVICE_NAME);
062 }
063
064 /**
065 * This allows you to pass in a context and a path to a template
066 * file and then grabs an instance of the velocity service and
067 * processes the template and returns the results as a String
068 * object.
069 *
070 * @param context A Context.
071 * @param template The path for the template files.
072 * @return A String.
073 * @exception Exception a generic exception.
074 */
075 public static String handleRequest(Context context, String template)
076 throws Exception
077 {
078 return getService().handleRequest(context, template);
079 }
080
081 /**
082 * Process the request and fill in the template with the values
083 * you set in the Context.
084 *
085 * @param context A Context.
086 * @param template A String with the filename of the template.
087 * @param out A OutputStream where we will write the process template as
088 * a String.
089 * @exception Exception a generic exception.
090 */
091 public static void handleRequest(Context context, String template,
092 OutputStream out)
093 throws Exception
094 {
095 getService().handleRequest(context, template, out);
096 }
097
098 /**
099 * Process the request and fill in the template with the values
100 * you set in the Context.
101 *
102 * @param context A Context.
103 * @param template A String with the filename of the template.
104 * @param writer A Writer where we will write the process template as
105 * a String.
106 * @exception Exception a generic exception.
107 */
108 public static void handleRequest(Context context,
109 String template,
110 Writer writer)
111 throws Exception
112 {
113 getService().handleRequest(context, template, writer);
114 }
115
116 /**
117 * This returns a Context that you can pass into handleRequest
118 * once you have populated it with information that the template
119 * will know about.
120 * @deprecated Use the PipelineData version instead.
121 * @param data A Turbine RunData.
122 * @return A Context.
123 */
124 public static Context getContext(RunData data)
125 {
126 return getService().getContext(data);
127 }
128
129 /**
130 * This returns a Context that you can pass into handleRequest
131 * once you have populated it with information that the template
132 * will know about.
133 *
134 * @param data A Turbine RunData.
135 * @return A Context.
136 */
137 public static Context getContext(PipelineData pipelineData)
138 {
139 return getService().getContext(pipelineData);
140 }
141
142 /**
143 * This method returns a blank Context object, which
144 * also contains the global context object. Do not use
145 * this method if you need an empty context object! Use
146 * getNewContext for this.
147 *
148 * @return A WebContext.
149 */
150 public static Context getContext()
151 {
152 return getService().getContext();
153 }
154
155 /**
156 * This method returns a new, empty Context object.
157 *
158 * @return A WebContext.
159 */
160 public static Context getNewContext()
161 {
162 return getService().getNewContext();
163 }
164
165 /**
166 * Performs post-request actions (releases context
167 * tools back to the object pool).
168 *
169 * @param context a Velocity Context
170 */
171 public static void requestFinished(Context context)
172 {
173 getService().requestFinished(context);
174 }
175 }