1 /*
2 * $Id: FreemarkerUtil.java 1360343 2012-07-11 18:35:52Z nlebas $
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
22 package org.apache.tiles.request.freemarker.autotag;
23
24 import freemarker.template.TemplateModel;
25 import freemarker.template.TemplateModelException;
26 import freemarker.template.utility.DeepUnwrap;
27
28 /**
29 * Utilities for FreeMarker usage in Tiles.
30 *
31 * @version $Rev: 1360343 $ $Date: 2012-07-12 04:35:52 +1000 (Thu, 12 Jul 2012) $
32 */
33 public final class FreemarkerUtil {
34
35 /**
36 * Private constructor to avoid instantiation.
37 */
38 private FreemarkerUtil() {
39 }
40
41 /**
42 * Unwraps a TemplateModel to extract an object.
43 *
44 * @param model The TemplateModel to unwrap.
45 * @param defaultValue The default value, as specified in the template
46 * model, or null if not specified.
47 * @return The unwrapped object.
48 */
49 public static <T> T getAsObject(TemplateModel model, Class<T> type, T defaultValue) {
50 try {
51 T retValue = defaultValue;
52 if (model != null) {
53 @SuppressWarnings("unchecked")
54 T value = (T) DeepUnwrap.unwrap(model);
55 if (value != null) {
56 retValue = value;
57 }
58 }
59 return retValue;
60 } catch (TemplateModelException e) {
61 throw new FreemarkerAutotagException("Cannot unwrap a model", e);
62 }
63 }
64 }