1 /*
2 * Copyright 2012-2013 smartics, Kronseder & Reiner GmbH
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16 package de.smartics.properties.api.config.app;
17
18 import static de.smartics.properties.api.config.domain.TypeProblemMessageBean.instantiationFailed;
19 import static de.smartics.properties.api.config.domain.TypeProblemMessageBean.noImplementationFound;
20 import de.smartics.properties.core.services.AbstractJndiBackedServiceFactory;
21 import de.smartics.properties.resource.domain.ResourceException;
22 import de.smartics.util.lang.Arg;
23
24 /**
25 * Creates instances of the {@link ConfigurationPropertiesFactory}.
26 * <p>
27 * Instances of {@link ConfigurationPropertiesFactory} create selected
28 * implementations of the
29 * {@link de.smartics.properties.api.config.domain.ConfigurationProperties}
30 * interface. This static factory of factories allows to create the factories.
31 * </p>
32 * <p>
33 * Factories can be created in two ways:
34 * </p>
35 * <ol>
36 * <li>Use {@link #createDefaultFactory()} if the name of the factory is
37 * supplied by <code>META-INF/services</code></li>
38 * <li>Use {@link #createFactory(Class)} or {@link #createFactory(String)} if
39 * the name is determined by the client code at runtime.</li>
40 * </ol>
41 * {@stickyNote Usually the second way (especially if a class is supplied) is
42 * not really necessary since the constructor can be called by the client code
43 * with the same effect. But using this factory of factories may be more
44 * convenient.}
45 */
46 public final class ConfigurationPropertiesFactoryFactory extends
47 AbstractJndiBackedServiceFactory<ConfigurationPropertiesFactory>
48 {
49 // ********************************* Fields *********************************
50
51 // --- constants ------------------------------------------------------------
52
53 /**
54 * The singleton.
55 */
56 public static final ConfigurationPropertiesFactoryFactory INSTANCE =
57 new ConfigurationPropertiesFactoryFactory();
58
59 // --- members --------------------------------------------------------------
60
61 // ****************************** Initializer *******************************
62
63 // ****************************** Constructors ******************************
64
65 /**
66 * Default constructor.
67 */
68 private ConfigurationPropertiesFactoryFactory()
69 {
70 super(ConfigurationPropertiesFactory.class);
71 }
72
73 // ****************************** Inner Classes *****************************
74
75 // ********************************* Methods ********************************
76
77 // --- init -----------------------------------------------------------------
78
79 // --- get&set --------------------------------------------------------------
80
81 // --- business -------------------------------------------------------------
82
83 /**
84 * Creates the default factory found on the class path. The factory class is
85 * registered in
86 * <code>META-INF/services/de.smartics.properties.api.config.app.ConfigurationPropertiesFactory</code>
87 * .
88 * <p>
89 * Issues a warning if more than one implementation is found. Returns an
90 * instance of the first implementation found.
91 * </p>
92 *
93 * @return the instance of the default factory. Never <code>null</code>.
94 * @throws ConfigurationFactoryException if no factory can be created.
95 */
96 public static ConfigurationPropertiesFactory createDefaultFactory()
97 throws ConfigurationFactoryException
98 {
99 try
100 {
101 try
102 {
103 @SuppressWarnings("rawtypes")
104 final Class defaultImpl =
105 ConfigurationPropertiesFactoryFactory.class
106 .getClassLoader()
107 .loadClass(
108 "de.smartics.properties.impl.config.properties.PropertiesConfigurationPropertiesFactory");
109 @SuppressWarnings("unchecked")
110 final ConfigurationPropertiesFactory factory =
111 INSTANCE.create(defaultImpl);
112 return factory;
113
114 }
115 catch (final ClassNotFoundException e)
116 {
117 // OK Do nothing
118 }
119 final ConfigurationPropertiesFactory factory = INSTANCE.create();
120 return factory;
121 }
122 catch (final ResourceException e)
123 {
124 throw new ConfigurationFactoryException(noImplementationFound(e,
125 ConfigurationPropertiesFactory.class));
126 }
127 }
128
129 /**
130 * Creates a factory of the given type.
131 *
132 * @param factoryType the type of the factory to create.
133 * @return the created instance. Never <code>null</code>.
134 * @throws NullPointerException if {@code factoryType} is <code>null</code>.
135 * @throws ConfigurationFactoryException on any problem creating the requested
136 * factory instance.
137 * @param <T> the type of the factory.
138 */
139 public static <T extends ConfigurationPropertiesFactory> T createFactory(
140 final Class<T> factoryType) throws NullPointerException,
141 ConfigurationFactoryException
142 {
143 Arg.checkNotNull("factoryType", factoryType);
144
145 try
146 {
147 return factoryType.newInstance();
148 }
149 catch (final Exception e)
150 {
151 throw new ConfigurationFactoryException(instantiationFailed(e,
152 factoryType));
153 }
154 }
155
156 /**
157 * Creates a factory for the given type name.
158 *
159 * @param factoryTypeName the fully qualified name of a type that implements
160 * {@link de.smartics.properties.api.config.domain.ConfigurationProperties}
161 * .
162 * @return the created instance. Never <code>null</code>.
163 * @throws NullPointerException if {@code factoryTypeName} is
164 * <code>null</code>.
165 * @throws ConfigurationFactoryException on any problem creating the requested
166 * factory instance.
167 */
168 @SuppressWarnings("unchecked")
169 public static ConfigurationPropertiesFactory createFactory(
170 final String factoryTypeName) throws NullPointerException,
171 ConfigurationFactoryException
172 {
173 Arg.checkNotNull("factoryTypeName", factoryTypeName);
174
175 try
176 {
177 final Class<? extends ConfigurationPropertiesFactory> factoryType =
178 (Class<? extends ConfigurationPropertiesFactory>) Class
179 .forName(factoryTypeName);
180 return createFactory(factoryType);
181 }
182 catch (final ClassNotFoundException e)
183 {
184 throw new ConfigurationFactoryException(instantiationFailed(e,
185 factoryTypeName));
186 }
187 }
188
189 // --- object basics --------------------------------------------------------
190
191 }