1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one or more
3 * contributor license agreements. See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * The ASF licenses this file to You under the Apache License, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License. You may obtain a copy of the License at
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17 package org.apache.commons.configuration2.builder.combined;
18
19 import java.util.Collection;
20 import java.util.Collections;
21 import java.util.Map;
22 import java.util.Set;
23 import java.util.stream.Collectors;
24
25 import org.apache.commons.configuration2.FileBasedConfiguration;
26 import org.apache.commons.configuration2.builder.FileBasedConfigurationBuilder;
27 import org.apache.commons.configuration2.builder.ReloadingFileBasedConfigurationBuilder;
28 import org.apache.commons.configuration2.ex.ConfigurationException;
29 import org.apache.commons.configuration2.reloading.CombinedReloadingController;
30 import org.apache.commons.configuration2.reloading.ReloadingController;
31 import org.apache.commons.configuration2.reloading.ReloadingControllerSupport;
32
33 /**
34 * <p>
35 * A specialized {@code MultiFileConfigurationBuilder} implementation which adds support for reloading.
36 * </p>
37 * <p>
38 * This class - as its super class - allows operating on multiple configuration files whose file names are determined
39 * using a file name pattern and a {@code ConfigurationInterpolator} object. It provides the following additional
40 * features:
41 * </p>
42 * <ul>
43 * <li>Configuration builder for managed configurations have reloading support. So reloading is possible for all
44 * configuration sources loaded by this builder instance.</li>
45 * <li>A {@link ReloadingController} is provided which can be used to trigger reload checks on all managed
46 * configurations.</li>
47 * </ul>
48 * <p>
49 * Although this builder manages an arbitrary number of child configurations, to clients only a single configuration is
50 * visible - the one selected by the evaluation of the file name pattern. Builder reset notifications triggered by the
51 * reloading mechanism do not really take this fact into account; they are not limited to the currently selected child
52 * configuration, but occur for each of the managed configuration.
53 * </p>
54 *
55 * @since 2.0
56 * @param <T> the concrete type of {@code Configuration} objects created by this builder
57 */
58 public class ReloadingMultiFileConfigurationBuilder<T extends FileBasedConfiguration> extends MultiFileConfigurationBuilder<T>
59 implements ReloadingControllerSupport {
60 /** The reloading controller used by this builder. */
61 private final ReloadingController reloadingController = createReloadingController();
62
63 /**
64 * Creates a new instance of {@code ReloadingMultiFileConfigurationBuilder} and sets initialization parameters and a
65 * flag whether initialization failures should be ignored.
66 *
67 * @param resCls the result configuration class
68 * @param params a map with initialization parameters
69 * @param allowFailOnInit a flag whether initialization errors should be ignored
70 * @throws IllegalArgumentException if the result class is <b>null</b>
71 */
72 public ReloadingMultiFileConfigurationBuilder(final Class<T> resCls, final Map<String, Object> params, final boolean allowFailOnInit) {
73 super(resCls, params, allowFailOnInit);
74 }
75
76 /**
77 * Creates a new instance of {@code ReloadingMultiFileConfigurationBuilder} and sets initialization parameters.
78 *
79 * @param resCls the result configuration class
80 * @param params a map with initialization parameters
81 * @throws IllegalArgumentException if the result class is <b>null</b>
82 */
83 public ReloadingMultiFileConfigurationBuilder(final Class<T> resCls, final Map<String, Object> params) {
84 super(resCls, params);
85 }
86
87 /**
88 * Creates a new instance of {@code ReloadingMultiFileConfigurationBuilder} without setting initialization parameters.
89 *
90 * @param resCls the result configuration class
91 * @throws IllegalArgumentException if the result class is <b>null</b>
92 */
93 public ReloadingMultiFileConfigurationBuilder(final Class<T> resCls) {
94 super(resCls);
95 }
96
97 /**
98 * {@inheritDoc} This implementation returns a special {@code ReloadingController} that delegates to the reloading
99 * controllers of the managed builders created so far.
100 */
101 @Override
102 public ReloadingController getReloadingController() {
103 return reloadingController;
104 }
105
106 /**
107 * {@inheritDoc} This implementation returns a file-based configuration builder with reloading support.
108 */
109 @Override
110 protected FileBasedConfigurationBuilder<T> createManagedBuilder(final String fileName, final Map<String, Object> params) throws ConfigurationException {
111 return new ReloadingFileBasedConfigurationBuilder<>(getResultClass(), params, isAllowFailOnInit());
112 }
113
114 /**
115 * Creates the reloading controller used by this builder. This method creates a specialized
116 * {@link CombinedReloadingController} which operates on the reloading controllers of the managed builders created so
117 * far.
118 *
119 * @return the newly created {@code ReloadingController}
120 */
121 private ReloadingController createReloadingController() {
122 final Set<ReloadingController> empty = Collections.emptySet();
123 return new CombinedReloadingController(empty) {
124 @Override
125 public Collection<ReloadingController> getSubControllers() {
126 return getManagedBuilders().values().stream().map(b -> ((ReloadingControllerSupport) b).getReloadingController()).collect(Collectors.toList());
127 }
128 };
129 }
130 }