001/* 002 * Licensed to the Apache Software Foundation (ASF) under one or more 003 * contributor license agreements. See the NOTICE file distributed with 004 * this work for additional information regarding copyright ownership. 005 * The ASF licenses this file to You under the Apache License, Version 2.0 006 * (the "License"); you may not use this file except in compliance with 007 * the License. You may obtain a copy of the License at 008 * 009 * http://www.apache.org/licenses/LICENSE-2.0 010 * 011 * Unless required by applicable law or agreed to in writing, software 012 * distributed under the License is distributed on an "AS IS" BASIS, 013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 014 * See the License for the specific language governing permissions and 015 * limitations under the License. 016 */ 017package org.apache.commons.configuration2.builder.combined; 018 019import java.util.Arrays; 020import java.util.Collection; 021 022import org.apache.commons.configuration2.CombinedConfiguration; 023import org.apache.commons.configuration2.Configuration; 024import org.apache.commons.configuration2.builder.BasicBuilderParameters; 025import org.apache.commons.configuration2.builder.BasicConfigurationBuilder; 026import org.apache.commons.configuration2.builder.BuilderParameters; 027 028/** 029 * <p> 030 * A specialized {@code ConfigurationBuilderProvider} implementation which deals 031 * with combined configuration builders. 032 * </p> 033 * <p> 034 * This class is used to support {@code <configuration>} elements in 035 * configuration definition files. The provider creates another 036 * {@link CombinedConfigurationBuilder} which inherits some of the properties 037 * from its parent builder. 038 * </p> 039 * 040 * @since 2.0 041 */ 042public class CombinedConfigurationBuilderProvider extends 043 BaseConfigurationBuilderProvider 044{ 045 /** Constant for the name of the supported builder class. */ 046 private static final String BUILDER_CLASS = 047 "org.apache.commons.configuration2.builder.combined.CombinedConfigurationBuilder"; 048 049 /** Constant for the name of the supported reloading builder class. */ 050 private static final String RELOADING_BUILDER_CLASS = 051 "org.apache.commons.configuration2.builder.combined.ReloadingCombinedConfigurationBuilder"; 052 053 /** Constant for the name of the supported configuration class. */ 054 private static final String CONFIGURATION_CLASS = 055 "org.apache.commons.configuration2.CombinedConfiguration"; 056 057 /** Constant for the combined configuration builder parameters class. */ 058 private static final String COMBINED_PARAMS = 059 "org.apache.commons.configuration2.builder.combined.CombinedBuilderParametersImpl"; 060 061 /** Constant for the name of the file-based builder parameters class. */ 062 private static final String FILE_PARAMS = 063 "org.apache.commons.configuration2.builder.FileBasedBuilderParametersImpl"; 064 065 /** 066 * Creates a new instance of {@code CombinedConfigurationBuilderProvider}. 067 */ 068 public CombinedConfigurationBuilderProvider() 069 { 070 super(BUILDER_CLASS, RELOADING_BUILDER_CLASS, CONFIGURATION_CLASS, 071 Arrays.asList(COMBINED_PARAMS, FILE_PARAMS)); 072 } 073 074 /** 075 * {@inheritDoc} This implementation creates the result builder object 076 * directly, not using reflection. (The reflection-based approach of the 077 * base class does not work here because a combined configuration builder 078 * has constructors with a different signature.) It also performs some 079 * additional initializations. 080 */ 081 @Override 082 protected BasicConfigurationBuilder<? extends Configuration> createBuilder( 083 final ConfigurationDeclaration decl, final Collection<BuilderParameters> params) 084 throws Exception 085 { 086 CombinedConfigurationBuilder builder; 087 if (decl.isReload()) 088 { 089 builder = new ReloadingCombinedConfigurationBuilder(); 090 } 091 else 092 { 093 builder = new CombinedConfigurationBuilder(); 094 } 095 decl.getConfigurationBuilder().initChildEventListeners(builder); 096 return builder; 097 } 098 099 /** 100 * {@inheritDoc} This implementation pre-fills basic parameters from the 101 * basic properties of the parent builder's result configuration. 102 */ 103 @Override 104 protected void initializeParameterObjects(final ConfigurationDeclaration decl, 105 final Collection<BuilderParameters> params) throws Exception 106 { 107 // we know that the first object is the combined builder parameters 108 // object 109 final BasicBuilderParameters basicParams = 110 (BasicBuilderParameters) params.iterator().next(); 111 setUpBasicParameters(decl.getConfigurationBuilder() 112 .getConfigurationUnderConstruction(), basicParams); 113 // now properties set explicitly can be overridden 114 super.initializeParameterObjects(decl, params); 115 } 116 117 /** 118 * Populates the specified parameters object with properties from the given 119 * configuration. This method is used to set default values for basic 120 * properties based on the result configuration of the parent builder. 121 * 122 * @param config the configuration whose properties are to be copied 123 * @param params the target parameters object 124 */ 125 private static void setUpBasicParameters(final CombinedConfiguration config, 126 final BasicBuilderParameters params) 127 { 128 params.setListDelimiterHandler(config.getListDelimiterHandler()) 129 .setLogger(config.getLogger()) 130 .setThrowExceptionOnMissing(config.isThrowExceptionOnMissing()) 131 .setConfigurationDecoder(config.getConfigurationDecoder()); 132 } 133}