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.Collection; 020 021import org.apache.commons.configuration2.builder.BuilderParameters; 022import org.apache.commons.configuration2.builder.FileBasedBuilderParametersImpl; 023import org.apache.commons.configuration2.ex.ConfigurationException; 024 025/** 026 * <p> 027 * A specialized implementation of {@link ConfigurationBuilderProvider} which 028 * determines the name of the result configuration class based on the extension 029 * of the file to load. 030 * </p> 031 * <p> 032 * This class works analogously to its base class {@link BaseConfigurationBuilderProvider}; 033 * especially, the resulting builder is created based on reflection. It extends 034 * the super class's functionality by a specific mechanism for determining the 035 * resulting configuration class: At construction time two configuration class 036 * names and a file extension are passed in. If a file name is provided in the 037 * builder's initialization parameters and this file name has the specified 038 * extension, then the first configuration class name is used; otherwise the 039 * default configuration class name is selected. 040 * </p> 041 * <p> 042 * There are some tags for {@code CombinedConfigurationProvider} which can 043 * produce different results depending on the configuration files they have to 044 * load. This class can be used to implement this feature in a generic way. 045 * </p> 046 * 047 * @version $Id: FileExtensionConfigurationBuilderProvider.java 1842194 2018-09-27 22:24:23Z ggregory $ 048 * @since 2.0 049 */ 050public class FileExtensionConfigurationBuilderProvider extends 051 BaseConfigurationBuilderProvider 052{ 053 /** Constant for the file extension separator. */ 054 private static final char EXT_SEPARATOR = '.'; 055 056 /** The matching configuration class. */ 057 private final String matchingConfigurationClass; 058 059 /** The file extension. */ 060 private final String extension; 061 062 /** 063 * Creates a new instance of 064 * {@code FileExtensionConfigurationBuilderProvider}. 065 * 066 * @param bldrCls the name of the builder class 067 * @param reloadBldrCls the name of a builder class to be used if reloading 068 * support is required (<b>null</b> if reloading is not supported) 069 * @param matchingConfigCls the name of the configuration class to be used 070 * if the provided file extension matches (must not be <b>null</b>) 071 * @param defConfigClass the name of the configuration class to be used if 072 * the provided file extension does not match (must not be 073 * <b>null</b>) 074 * @param ext the file extension to select the configuration class (must not 075 * be <b>null</b>) 076 * @param paramCls a collection with the names of parameters classes; an 077 * instance of a parameters object with basic properties is created 078 * automatically and does not need to be contained in this list; the 079 * collection can be <b>null</b> if no additional parameter objects 080 * are needed 081 * @throws IllegalArgumentException if a required parameter is missing 082 */ 083 public FileExtensionConfigurationBuilderProvider(final String bldrCls, 084 final String reloadBldrCls, final String matchingConfigCls, 085 final String defConfigClass, final String ext, final Collection<String> paramCls) 086 { 087 super(bldrCls, reloadBldrCls, defConfigClass, paramCls); 088 if (matchingConfigCls == null) 089 { 090 throw new IllegalArgumentException( 091 "Matching configuration class must not be null!"); 092 } 093 if (ext == null) 094 { 095 throw new IllegalArgumentException( 096 "File extension must not be null!"); 097 } 098 099 matchingConfigurationClass = matchingConfigCls; 100 extension = ext; 101 } 102 103 /** 104 * Returns the name of the matching configuration class. This class is used 105 * if the file extension matches the extension of this provider. 106 * 107 * @return the matching configuration class 108 */ 109 public String getMatchingConfigurationClass() 110 { 111 return matchingConfigurationClass; 112 } 113 114 /** 115 * Returns the file extension of this provider. 116 * 117 * @return the file extension to match 118 */ 119 public String getExtension() 120 { 121 return extension; 122 } 123 124 /** 125 * {@inheritDoc} This implementation tries to find a 126 * {@link FileBasedBuilderParametersImpl} object in the parameter objects. If 127 * one is found, the extension of the file name is obtained and compared 128 * against the stored file extension. In case of a match, the matching 129 * configuration class is selected, otherwise the default one. 130 */ 131 @Override 132 protected String determineConfigurationClass(final ConfigurationDeclaration decl, 133 final Collection<BuilderParameters> params) throws ConfigurationException 134 { 135 final String currentExt = extractExtension(fetchCurrentFileName(params)); 136 return getExtension().equalsIgnoreCase(currentExt) ? getMatchingConfigurationClass() 137 : getConfigurationClass(); 138 } 139 140 /** 141 * Tries to obtain the current file name from the given list of parameter 142 * objects. 143 * 144 * @param params the parameter objects 145 * @return the file name or <b>null</b> if unspecified 146 */ 147 private static String fetchCurrentFileName( 148 final Collection<BuilderParameters> params) 149 { 150 for (final BuilderParameters p : params) 151 { 152 if (p instanceof FileBasedBuilderParametersImpl) 153 { 154 final FileBasedBuilderParametersImpl fp = (FileBasedBuilderParametersImpl) p; 155 return fp.getFileHandler().getFileName(); 156 } 157 } 158 return null; 159 } 160 161 /** 162 * Extracts the extension from the given file name. The name can be 163 * <b>null</b>. 164 * 165 * @param fileName the file name 166 * @return the extension (<b>null</b> if there is none) 167 */ 168 private static String extractExtension(final String fileName) 169 { 170 if (fileName == null) 171 { 172 return null; 173 } 174 175 final int pos = fileName.lastIndexOf(EXT_SEPARATOR); 176 return (pos < 0) ? null : fileName.substring(pos + 1); 177 } 178}