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.resolver; 018 019import java.io.IOException; 020import java.io.InputStream; 021import java.net.URL; 022import java.net.URLConnection; 023import java.util.HashMap; 024import java.util.Map; 025 026import org.xml.sax.EntityResolver; 027import org.xml.sax.InputSource; 028import org.xml.sax.SAXException; 029 030/** 031 * The DefaultEntityResolver used by XML Configurations. 032 * @author <a 033 * href="http://commons.apache.org/configuration/team-list.html">Commons 034 * Configuration team</a> 035 * @since 1.7 036 * @version $Id: DefaultEntityResolver.java 1842194 2018-09-27 22:24:23Z ggregory $ 037 */ 038public class DefaultEntityResolver implements EntityResolver, EntityRegistry 039{ 040 /** Stores a map with the registered public IDs.*/ 041 private final Map<String, URL> registeredEntities = new HashMap<>(); 042 043 /** 044 * <p> 045 * Registers the specified URL for the specified public identifier. 046 * </p> 047 * <p> 048 * This implementation maps {@code PUBLICID}'s to URLs (from which 049 * the resource will be loaded). A common use case for this method is to 050 * register local URLs (possibly computed at runtime by a class loader) for 051 * DTDs and Schemas. This allows the performance advantage of using a local 052 * version without having to ensure every {@code SYSTEM} URI on every 053 * processed XML document is local. This implementation provides only basic 054 * functionality. If more sophisticated features are required, either calling 055 * {@code XMLConfiguration.setDocumentBuilder(DocumentBuilder)} to set a custom 056 * {@code DocumentBuilder} (which also can be initialized with a 057 * custom {@code EntityResolver}) or creating a custom entity resolver 058 * and registering it with the XMLConfiguration is recommended. 059 * </p> 060 * 061 * @param publicId Public identifier of the Entity to be resolved 062 * @param entityURL The URL to use for reading this Entity 063 * @throws IllegalArgumentException if the public ID is undefined 064 */ 065 @Override 066 public void registerEntityId(final String publicId, final URL entityURL) 067 { 068 if (publicId == null) 069 { 070 throw new IllegalArgumentException("Public ID must not be null!"); 071 } 072 getRegisteredEntities().put(publicId, entityURL); 073 } 074 075 /** 076 * Resolves the requested external entity. This is the default 077 * implementation of the {@code EntityResolver} interface. It checks 078 * the passed in public ID against the registered entity IDs and uses a 079 * local URL if possible. 080 * 081 * @param publicId the public identifier of the entity being referenced 082 * @param systemId the system identifier of the entity being referenced 083 * @return an input source for the specified entity 084 * @throws org.xml.sax.SAXException if a parsing exception occurs 085 */ 086 @Override 087 public InputSource resolveEntity(final String publicId, final String systemId) 088 throws SAXException 089 { 090 // Has this system identifier been registered? 091 URL entityURL = null; 092 if (publicId != null) 093 { 094 entityURL = getRegisteredEntities().get(publicId); 095 } 096 097 if (entityURL != null) 098 { 099 // Obtain an InputSource for this URL. This code is based on the 100 // createInputSourceFromURL() method of Commons Digester. 101 try 102 { 103 final URLConnection connection = entityURL.openConnection(); 104 connection.setUseCaches(false); 105 final InputStream stream = connection.getInputStream(); 106 final InputSource source = new InputSource(stream); 107 source.setSystemId(entityURL.toExternalForm()); 108 return source; 109 } 110 catch (final IOException e) 111 { 112 throw new SAXException(e); 113 } 114 } 115 // default processing behavior 116 return null; 117 } 118 119 /** 120 * Returns a map with the entity IDs that have been registered using the 121 * {@code registerEntityId()} method. 122 * 123 * @return a map with the registered entity IDs 124 */ 125 @Override 126 public Map<String, URL> getRegisteredEntities() 127 { 128 return registeredEntities; 129 } 130}