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 * https://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.Arrays;
20 import java.util.Collection;
21
22 import org.apache.commons.configuration2.CombinedConfiguration;
23 import org.apache.commons.configuration2.Configuration;
24 import org.apache.commons.configuration2.builder.BasicBuilderParameters;
25 import org.apache.commons.configuration2.builder.BasicConfigurationBuilder;
26 import org.apache.commons.configuration2.builder.BuilderParameters;
27
28 /**
29 * <p>
30 * A specialized {@code ConfigurationBuilderProvider} implementation which deals with combined configuration builders.
31 * </p>
32 * <p>
33 * This class is used to support {@code <configuration>} elements in configuration definition files. The provider
34 * creates another {@link CombinedConfigurationBuilder} which inherits some of the properties from its parent builder.
35 * </p>
36 *
37 * @since 2.0
38 */
39 public class CombinedConfigurationBuilderProvider extends BaseConfigurationBuilderProvider {
40
41 /** Constant for the name of the supported builder class. */
42 private static final String BUILDER_CLASS = "org.apache.commons.configuration2.builder.combined.CombinedConfigurationBuilder";
43
44 /** Constant for the name of the supported reloading builder class. */
45 private static final String RELOADING_BUILDER_CLASS = "org.apache.commons.configuration2.builder.combined.ReloadingCombinedConfigurationBuilder";
46
47 /** Constant for the name of the supported configuration class. */
48 private static final String CONFIGURATION_CLASS = "org.apache.commons.configuration2.CombinedConfiguration";
49
50 /** Constant for the combined configuration builder parameters class. */
51 private static final String COMBINED_PARAMS = "org.apache.commons.configuration2.builder.combined.CombinedBuilderParametersImpl";
52
53 /** Constant for the name of the file-based builder parameters class. */
54 private static final String FILE_PARAMS = "org.apache.commons.configuration2.builder.FileBasedBuilderParametersImpl";
55
56 /**
57 * Populates the specified parameters object with properties from the given configuration. This method is used to set
58 * default values for basic properties based on the result configuration of the parent builder.
59 *
60 * @param config the configuration whose properties are to be copied
61 * @param params the target parameters object
62 */
63 private static void setUpBasicParameters(final CombinedConfiguration config, final BasicBuilderParameters params) {
64 params.setListDelimiterHandler(config.getListDelimiterHandler()).setLogger(config.getLogger())
65 .setThrowExceptionOnMissing(config.isThrowExceptionOnMissing()).setConfigurationDecoder(config.getConfigurationDecoder());
66 }
67
68 /**
69 * Creates a new instance of {@code CombinedConfigurationBuilderProvider}.
70 */
71 public CombinedConfigurationBuilderProvider() {
72 super(BUILDER_CLASS, RELOADING_BUILDER_CLASS, CONFIGURATION_CLASS, Arrays.asList(COMBINED_PARAMS, FILE_PARAMS));
73 }
74
75 /**
76 * {@inheritDoc} This implementation creates the result builder object directly, not using reflection. (The
77 * reflection-based approach of the base class does not work here because a combined configuration builder has
78 * constructors with a different signature.) It also performs some additional initializations.
79 */
80 @Override
81 protected BasicConfigurationBuilder<? extends Configuration> createBuilder(final ConfigurationDeclaration decl, final Collection<BuilderParameters> params)
82 throws Exception {
83 final CombinedConfigurationBuilder builder;
84 if (decl.isReload()) {
85 builder = new ReloadingCombinedConfigurationBuilder();
86 } else {
87 builder = new CombinedConfigurationBuilder();
88 }
89 decl.getConfigurationBuilder().initChildEventListeners(builder);
90 return builder;
91 }
92
93 /**
94 * {@inheritDoc} This implementation pre-fills basic parameters from the basic properties of the parent builder's result
95 * configuration.
96 */
97 @Override
98 protected void initializeParameterObjects(final ConfigurationDeclaration decl, final Collection<BuilderParameters> params) throws Exception {
99 // we know that the first object is the combined builder parameters
100 // object
101 final BasicBuilderParameters basicParams = (BasicBuilderParameters) params.iterator().next();
102 setUpBasicParameters(decl.getConfigurationBuilder().getConfigurationUnderConstruction(), basicParams);
103 // now properties set explicitly can be overridden
104 super.initializeParameterObjects(decl, params);
105 }
106 }