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1   /*
2    * $Id: FreemarkerTemplateEngine.java 474191 2006-11-13 08:30:40Z mrdon $
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  package org.apache.struts2.components.template;
22  
23  import java.io.IOException;
24  import java.io.Writer;
25  import java.util.Iterator;
26  import java.util.List;
27  import java.util.Map;
28  
29  import javax.servlet.ServletContext;
30  import javax.servlet.http.HttpServletRequest;
31  import javax.servlet.http.HttpServletResponse;
32  
33  import org.apache.commons.logging.Log;
34  import org.apache.commons.logging.LogFactory;
35  import org.apache.struts2.ServletActionContext;
36  import org.apache.struts2.views.freemarker.FreemarkerManager;
37  
38  import com.opensymphony.xwork2.inject.Inject;
39  import com.opensymphony.xwork2.util.ClassLoaderUtil;
40  import com.opensymphony.xwork2.ActionContext;
41  import com.opensymphony.xwork2.ActionInvocation;
42  import com.opensymphony.xwork2.util.ValueStack;
43  
44  import freemarker.template.Configuration;
45  import freemarker.template.SimpleHash;
46  
47  /***
48   * Freemarker based template engine.
49   */
50  public class FreemarkerTemplateEngine extends BaseTemplateEngine {
51      static Class bodyContent = null;
52      private FreemarkerManager freemarkerManager;
53  
54      static {
55          try {
56              bodyContent = ClassLoaderUtil.loadClass("javax.servlet.jsp.tagext.BodyContent",
57                      FreemarkerTemplateEngine.class);
58          } catch (ClassNotFoundException e) {
59              // this is OK -- this just means JSP isn't even being used here, which is perfectly fine.
60              // we need this class in environments that use JSP to know when to wrap the writer
61              // and ignore flush() calls. In JSP, it is illegal for a BodyContent writer to be flushed(),
62              // so we have to take caution here.
63          }
64      }
65  
66      private static final Log LOG = LogFactory.getLog(FreemarkerTemplateEngine.class);
67  
68      @Inject
69      public void setFreemarkerManager(FreemarkerManager mgr) {
70          this.freemarkerManager = mgr;
71      }
72      
73      public void renderTemplate(TemplateRenderingContext templateContext) throws Exception {
74          // get the various items required from the stack
75          ValueStack stack = templateContext.getStack();
76          Map context = stack.getContext();
77          ServletContext servletContext = (ServletContext) context.get(ServletActionContext.SERVLET_CONTEXT);
78          HttpServletRequest req = (HttpServletRequest) context.get(ServletActionContext.HTTP_REQUEST);
79          HttpServletResponse res = (HttpServletResponse) context.get(ServletActionContext.HTTP_RESPONSE);
80  
81          // prepare freemarker
82          Configuration config = freemarkerManager.getConfiguration(servletContext);
83  
84          // get the list of templates we can use
85          List templates = templateContext.getTemplate().getPossibleTemplates(this);
86  
87          // find the right template
88          freemarker.template.Template template = null;
89          String templateName = null;
90          Exception exception = null;
91          for (Iterator iterator = templates.iterator(); iterator.hasNext();) {
92              Template t = (Template) iterator.next();
93              templateName = getFinalTemplateName(t);
94              try {
95                  // try to load, and if it works, stop at the first one
96                  template = config.getTemplate(templateName);
97                  break;
98              } catch (IOException e) {
99                  if (exception == null) {
100                     exception = e;
101                 }
102             }
103         }
104 
105         if (template == null) {
106             LOG.error("Could not load template " + templateContext.getTemplate());
107             if (exception != null) {
108                 throw exception;
109             } else {
110                 return;
111             }
112         }
113 
114         if (LOG.isDebugEnabled()) {
115             LOG.debug("Rendering template " + templateName);
116         }
117 
118         ActionInvocation ai = ActionContext.getContext().getActionInvocation();
119 
120         Object action = (ai == null) ? null : ai.getAction();
121         SimpleHash model = freemarkerManager.buildTemplateModel(stack, action, servletContext, req, res, config.getObjectWrapper());
122 
123         model.put("tag", templateContext.getTag());
124         model.put("themeProperties", getThemeProps(templateContext.getTemplate()));
125 
126         // the BodyContent JSP writer doesn't like it when FM flushes automatically --
127         // so let's just not do it (it will be flushed eventually anyway)
128         Writer writer = templateContext.getWriter();
129         if (bodyContent != null && bodyContent.isAssignableFrom(writer.getClass())) {
130             final Writer wrapped = writer;
131             writer = new Writer() {
132                 public void write(char cbuf[], int off, int len) throws IOException {
133                     wrapped.write(cbuf, off, len);
134                 }
135 
136                 public void flush() throws IOException {
137                     // nothing!
138                 }
139 
140                 public void close() throws IOException {
141                     wrapped.close();
142                 }
143             };
144         }
145 
146         try {
147             stack.push(templateContext.getTag());
148             template.process(model, writer);
149         } finally {
150             stack.pop();
151         }
152     }
153 
154     protected String getSuffix() {
155         return "ftl";
156     }
157 }