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 with combined configuration builders. 031 * </p> 032 * <p> 033 * This class is used to support {@code <configuration>} elements in configuration definition files. The provider 034 * creates another {@link CombinedConfigurationBuilder} which inherits some of the properties from its parent builder. 035 * </p> 036 * 037 * @since 2.0 038 */ 039public class CombinedConfigurationBuilderProvider extends BaseConfigurationBuilderProvider { 040 /** Constant for the name of the supported builder class. */ 041 private static final String BUILDER_CLASS = "org.apache.commons.configuration2.builder.combined.CombinedConfigurationBuilder"; 042 043 /** Constant for the name of the supported reloading builder class. */ 044 private static final String RELOADING_BUILDER_CLASS = "org.apache.commons.configuration2.builder.combined.ReloadingCombinedConfigurationBuilder"; 045 046 /** Constant for the name of the supported configuration class. */ 047 private static final String CONFIGURATION_CLASS = "org.apache.commons.configuration2.CombinedConfiguration"; 048 049 /** Constant for the combined configuration builder parameters class. */ 050 private static final String COMBINED_PARAMS = "org.apache.commons.configuration2.builder.combined.CombinedBuilderParametersImpl"; 051 052 /** Constant for the name of the file-based builder parameters class. */ 053 private static final String FILE_PARAMS = "org.apache.commons.configuration2.builder.FileBasedBuilderParametersImpl"; 054 055 /** 056 * Creates a new instance of {@code CombinedConfigurationBuilderProvider}. 057 */ 058 public CombinedConfigurationBuilderProvider() { 059 super(BUILDER_CLASS, RELOADING_BUILDER_CLASS, CONFIGURATION_CLASS, Arrays.asList(COMBINED_PARAMS, FILE_PARAMS)); 060 } 061 062 /** 063 * {@inheritDoc} This implementation creates the result builder object directly, not using reflection. (The 064 * reflection-based approach of the base class does not work here because a combined configuration builder has 065 * constructors with a different signature.) It also performs some additional initializations. 066 */ 067 @Override 068 protected BasicConfigurationBuilder<? extends Configuration> createBuilder(final ConfigurationDeclaration decl, final Collection<BuilderParameters> params) 069 throws Exception { 070 final CombinedConfigurationBuilder builder; 071 if (decl.isReload()) { 072 builder = new ReloadingCombinedConfigurationBuilder(); 073 } else { 074 builder = new CombinedConfigurationBuilder(); 075 } 076 decl.getConfigurationBuilder().initChildEventListeners(builder); 077 return builder; 078 } 079 080 /** 081 * {@inheritDoc} This implementation pre-fills basic parameters from the basic properties of the parent builder's result 082 * configuration. 083 */ 084 @Override 085 protected void initializeParameterObjects(final ConfigurationDeclaration decl, final Collection<BuilderParameters> params) throws Exception { 086 // we know that the first object is the combined builder parameters 087 // object 088 final BasicBuilderParameters basicParams = (BasicBuilderParameters) params.iterator().next(); 089 setUpBasicParameters(decl.getConfigurationBuilder().getConfigurationUnderConstruction(), basicParams); 090 // now properties set explicitly can be overridden 091 super.initializeParameterObjects(decl, params); 092 } 093 094 /** 095 * Populates the specified parameters object with properties from the given configuration. This method is used to set 096 * default values for basic properties based on the result configuration of the parent builder. 097 * 098 * @param config the configuration whose properties are to be copied 099 * @param params the target parameters object 100 */ 101 private static void setUpBasicParameters(final CombinedConfiguration config, final BasicBuilderParameters params) { 102 params.setListDelimiterHandler(config.getListDelimiterHandler()).setLogger(config.getLogger()) 103 .setThrowExceptionOnMissing(config.isThrowExceptionOnMissing()).setConfigurationDecoder(config.getConfigurationDecoder()); 104 } 105}