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