1 /**
2 * This file Copyright (c) 2010-2011 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.objectfactory;
35
36 import info.magnolia.cms.core.SystemProperty;
37 import org.apache.commons.lang.StringUtils;
38
39 import java.lang.reflect.Modifier;
40
41 /**
42 * Entry point to the currently configured ClassFactory, as well as some additional utility methods for manipulating Class objects.
43 *
44 * @see info.magnolia.objectfactory.ClassFactory
45 *
46 * @author gjoseph
47 * @version $Revision: $ ($Author: $)
48 */
49 public class Classes {
50 private final static org.slf4j.Logger log = org.slf4j.LoggerFactory.getLogger(Classes.class);
51
52 public static boolean isConcrete(Class<?> clazz) {
53 if (clazz == null) {
54 // null class is not concrete .... ever
55 return false;
56 }
57 return !Modifier.isAbstract(clazz.getModifiers());
58 }
59
60 /**
61 * Convenience/shortcut method for instantiating new classes.
62 * @see info.magnolia.objectfactory.ClassFactory
63 * @see #getClassFactory()
64 * @throws ClassNotFoundException
65 * @throws MgnlInstantiationException
66 */
67 public static <T> T newInstance(String className, Object... params) throws ClassNotFoundException {
68 final ClassFactory cf = getClassFactory();
69 final Class<T> cl = cf.forName(className);
70 return cf.newInstance(cl, params);
71 }
72
73 /**
74 * Convenience/shortcut for {@link #newInstance(String, Object...)}, returning null both in case
75 * of a ClassNotFoundException or if the class could not be instantiated.
76 * (which could be related to the parameters, etc)
77 */
78 public static <T> T quietNewInstance(String className, Object... params) {
79 try {
80 return Classes.<T>newInstance(className, params);
81 } catch (ClassNotFoundException e) {
82 log.warn("Couldn't find class with name {}", className);
83 return null;
84 } catch (MgnlInstantiationException e) {
85 log.warn("Couldn't instantiate {}: {}", className, e.getMessage());
86 return null;
87 }
88 }
89
90 public static ClassFactory getClassFactory() {
91 return cfp.current();
92 }
93
94 // this field should be final but isn't, for tests' sake
95 private static ClassFactoryProvider cfp = new ClassFactoryProvider(new DefaultClassFactory());
96
97 /**
98 * ClassFactoryProvider is used to hide the "swapability" of ClassFactory.
99 * This current implementation checks the current instance versus the configured property
100 * on every call.
101 * TODO : This could possibly be optimized or "blocked" as soon as we can now this property has indeed been configured.
102 * I don't think the above would be interesting until we can do some refactoring of the ConfigLoader, PropertiesInitializer and SystemProperty classes.
103 */
104 protected static class ClassFactoryProvider {
105 private ClassFactory initial;
106 private ClassFactory current;
107 private boolean swapping;
108
109 public ClassFactoryProvider(ClassFactory initial) {
110 this.initial = initial;
111 this.current = initial;
112 }
113
114 public ClassFactory current() {
115 check();
116 return current;
117 }
118
119 private void check() {
120 final String configuredCFClassName = getCurrentlyConfiguredClassName();
121 final String currentCFClassName = current.getClass().getName();
122 if (StringUtils.isNotEmpty(configuredCFClassName) && !currentCFClassName.equals(configuredCFClassName) && !swapping) {
123 // we need to swap this instance, but other calls should not try to do it until we're done
124 swapping = true;
125
126 // whichever ClassFactory is registered will be instantiated with the initial ClassFactory.
127 try {
128 final Class<ClassFactory> c = initial.forName(configuredCFClassName);
129 current = initial.newInstance(c);
130 } catch (ClassNotFoundException e) {
131 log.error("Could not find {}, will keep on using {} for now", configuredCFClassName, current.getClass().getSimpleName());
132 }
133 swapping = false;
134 }
135 }
136
137 protected String getCurrentlyConfiguredClassName() {
138 return SystemProperty.getProperty(ClassFactory.class.getName());
139 }
140 }
141
142 }