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