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Java > Open Source Codes > org > apache > turbine > services > velocity > TurbineVelocity


1 package org.apache.turbine.services.velocity;
2
3 /*
4  * Copyright 2001-2004 The Apache Software Foundation.
5  *
6  * Licensed under the Apache License, Version 2.0 (the "License")
7  * you may not use this file except in compliance with the License.
8  * You may obtain a copy of the License at
9  *
10  * http://www.apache.org/licenses/LICENSE-2.0
11  *
12  * Unless required by applicable law or agreed to in writing, software
13  * distributed under the License is distributed on an "AS IS" BASIS,
14  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
15  * See the License for the specific language governing permissions and
16  * limitations under the License.
17  */
18
19 import java.io.OutputStream JavaDoc;
20 import java.io.Writer JavaDoc;
21
22 import org.apache.turbine.services.TurbineServices;
23 import org.apache.turbine.util.RunData;
24
25 import org.apache.velocity.context.Context;
26
27 /**
28  * This is a simple static accessor to common Velocity tasks such as
29  * getting an instance of a context as well as handling a request for
30  * processing a template.
31  * <pre>
32  * Context context = TurbineVelocity.getContext(data);
33  * context.put("message", "Hello from Turbine!");
34  * String results = TurbineVelocity.handleRequest(context, "helloWorld.vm");
35  * data.getPage().getBody().addElement(results);
36  * </pre>
37  *
38  * @author <a HREF="mailto:john.mcnally@clearink.com">John D. McNally</a>
39  * @author <a HREF="mailto:jon@latchkey.com">Jon S. Stevens</a>
40  * @author <a HREF="mailto:jvanzyl@periapt.com.com">Jason van Zyl</a>
41  * @version $Id: TurbineVelocity.java,v 1.7.2.2 2004/05/20 03:06:50 seade Exp $
42  */
43 public abstract class TurbineVelocity
44 {
45     /**
46      * Utility method for accessing the service
47      * implementation
48      *
49      * @return a VelocityService implementation instance
50      */
51     public static VelocityService getService()
52     {
53         return (VelocityService) TurbineServices
54                 .getInstance().getService(VelocityService.SERVICE_NAME);
55     }
56
57     /**
58      * This allows you to pass in a context and a path to a template
59      * file and then grabs an instance of the velocity service and
60      * processes the template and returns the results as a String
61      * object.
62      *
63      * @param context A Context.
64      * @param template The path for the template files.
65      * @return A String.
66      * @exception Exception a generic exception.
67      */
68     public static String JavaDoc handleRequest(Context context, String JavaDoc template)
69             throws Exception JavaDoc
70     {
71         return getService().handleRequest(context, template);
72     }
73
74     /**
75      * Process the request and fill in the template with the values
76      * you set in the Context.
77      *
78      * @param context A Context.
79      * @param template A String with the filename of the template.
80      * @param out A OutputStream where we will write the process template as
81      * a String.
82      * @exception Exception a generic exception.
83      */
84     public static void handleRequest(Context context, String JavaDoc template,
85                                      OutputStream JavaDoc out)
86             throws Exception JavaDoc
87     {
88         getService().handleRequest(context, template, out);
89     }
90
91     /**
92      * Process the request and fill in the template with the values
93      * you set in the Context.
94      *
95      * @param context A Context.
96      * @param template A String with the filename of the template.
97      * @param writer A Writer where we will write the process template as
98      * a String.
99      * @exception Exception a generic exception.
100      */
101     public static void handleRequest(Context context,
102                                      String JavaDoc template,
103                                      Writer JavaDoc writer)
104             throws Exception JavaDoc
105     {
106         getService().handleRequest(context, template, writer);
107     }
108
109     /**
110      * This returns a Context that you can pass into handleRequest
111      * once you have populated it with information that the template
112      * will know about.
113      *
114      * @param data A Turbine RunData.
115      * @return A Context.
116      */
117     public static Context getContext(RunData data)
118     {
119         return getService().getContext(data);
120     }
121
122     /**
123      * This method returns a blank Context object, which
124      * also contains the global context object. Do not use
125      * this method if you need an empty context object! Use
126      * getNewContext for this.
127      *
128      * @return A WebContext.
129      */
130     public static Context getContext()
131     {
132         return getService().getContext();
133     }
134
135     /**
136      * This method returns a new, empty Context object.
137      *
138      * @return A WebContext.
139      */
140     public static Context getNewContext()
141     {
142         return getService().getNewContext();
143     }
144
145     /**
146      * Performs post-request actions (releases context
147      * tools back to the object pool).
148      *
149      * @param context a Velocity Context
150      */
151     public static void requestFinished(Context context)
152     {
153         getService().requestFinished(context);
154     }
155 }
156
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