1 /**
2 * This file Copyright (c) 2003-2015 Magnolia International
3 * Ltd. (http://www.magnolia-cms.com). All rights reserved.
4 *
5 *
6 * This file is dual-licensed under both the Magnolia
7 * Network Agreement and the GNU General Public License.
8 * You may elect to use one or the other of these licenses.
9 *
10 * This file is distributed in the hope that it will be
11 * useful, but AS-IS and WITHOUT ANY WARRANTY; without even the
12 * implied warranty of MERCHANTABILITY or FITNESS FOR A
13 * PARTICULAR PURPOSE, TITLE, or NONINFRINGEMENT.
14 * Redistribution, except as permitted by whichever of the GPL
15 * or MNA you select, is prohibited.
16 *
17 * 1. For the GPL license (GPL), you can redistribute and/or
18 * modify this file under the terms of the GNU General
19 * Public License, Version 3, as published by the Free Software
20 * Foundation. You should have received a copy of the GNU
21 * General Public License, Version 3 along with this program;
22 * if not, write to the Free Software Foundation, Inc., 51
23 * Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
24 *
25 * 2. For the Magnolia Network Agreement (MNA), this file
26 * and the accompanying materials are made available under the
27 * terms of the MNA which accompanies this distribution, and
28 * is available at http://www.magnolia-cms.com/mna.html
29 *
30 * Any modifications to this file must keep this entire header
31 * intact.
32 *
33 */
34 package info.magnolia.freemarker.loaders;
35
36 import java.io.IOException;
37 import java.io.Reader;
38
39 import freemarker.cache.TemplateLoader;
40
41 /**
42 * An abstract TemplateLoader that will attempt to initialize its delegate TemplateLoader
43 * and use a null object implementation until it succeeds. This allows us to wrap existing,
44 * constructor-configured TemplateLoader implementations, into content2bean-able beans,
45 * thus making them configurable in Magnolia's config repository.
46 */
47 public abstract class AbstractDelegatingTemplateLoader implements TemplateLoader {
48 private static final TemplateLoader NULL = new NullTemplateLoader();
49
50 private TemplateLoader delegate;
51
52 @Override
53 public Object findTemplateSource(String name) throws IOException {
54 return getDelegate().findTemplateSource(name);
55 }
56
57 @Override
58 public long getLastModified(Object templateSource) {
59 return getDelegate().getLastModified(templateSource);
60 }
61
62 @Override
63 public Reader getReader(Object templateSource, String encoding) throws IOException {
64 return getDelegate().getReader(templateSource, encoding);
65 }
66
67 @Override
68 public void closeTemplateSource(Object templateSource) throws IOException {
69 getDelegate().closeTemplateSource(templateSource);
70 }
71
72 /**
73 * First attempts to initialize a new delegate if needed. If it doesn't succeed, use the NullTemplateLoader.
74 */
75 protected TemplateLoader getDelegate() {
76 if (delegate == null) {
77 delegate = newDelegate();
78 }
79 if (delegate == null) {
80 return NULL;
81 }
82 return delegate;
83 }
84
85 /**
86 * Implementations should return null if it is too early to instantiate the delegate.
87 */
88 protected abstract TemplateLoader newDelegate();
89
90 private static class NullTemplateLoader implements TemplateLoader {
91 @Override
92 public Object findTemplateSource(String name) throws IOException {
93 return null;
94 }
95
96 @Override
97 public long getLastModified(Object templateSource) {
98 return -1;
99 }
100
101 @Override
102 public Reader getReader(Object templateSource, String encoding) throws IOException {
103 return null;
104 }
105
106 @Override
107 public void closeTemplateSource(Object templateSource) throws IOException {
108 }
109 }
110 }