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 * 033 * @since 1.7 034 */ 035public class DefaultEntityResolver implements EntityResolver, EntityRegistry { 036 /** Stores a map with the registered public IDs. */ 037 private final Map<String, URL> registeredEntities = new HashMap<>(); 038 039 /** 040 * Gets a map with the entity IDs that have been registered using the {@code registerEntityId()} method. 041 * 042 * @return a map with the registered entity IDs 043 */ 044 @Override 045 public Map<String, URL> getRegisteredEntities() { 046 return registeredEntities; 047 } 048 049 /** 050 * <p> 051 * Registers the specified URL for the specified public identifier. 052 * </p> 053 * <p> 054 * This implementation maps {@code PUBLICID}'s to URLs (from which the resource will be loaded). A common use case for 055 * this method is to register local URLs (possibly computed at runtime by a class loader) for DTDs and Schemas. This 056 * allows the performance advantage of using a local version without having to ensure every {@code SYSTEM} URI on every 057 * processed XML document is local. This implementation provides only basic functionality. If more sophisticated 058 * features are required, either calling {@code XMLConfiguration.setDocumentBuilder(DocumentBuilder)} to set a custom 059 * {@code DocumentBuilder} (which also can be initialized with a custom {@code EntityResolver}) or creating a custom 060 * entity resolver and registering it with the XMLConfiguration is recommended. 061 * </p> 062 * 063 * @param publicId Public identifier of the Entity to be resolved 064 * @param entityURL The URL to use for reading this Entity 065 * @throws IllegalArgumentException if the public ID is undefined 066 */ 067 @Override 068 public void registerEntityId(final String publicId, final URL entityURL) { 069 if (publicId == null) { 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 implementation of the {@code EntityResolver} interface. 077 * It checks the passed in public ID against the registered entity IDs and uses a local URL if possible. 078 * 079 * @param publicId the public identifier of the entity being referenced 080 * @param systemId the system identifier of the entity being referenced 081 * @return an input source for the specified entity 082 * @throws org.xml.sax.SAXException if a parsing exception occurs 083 */ 084 @SuppressWarnings("resource") // The stream is managed by the InputSource returned by this method. 085 @Override 086 public InputSource resolveEntity(final String publicId, final String systemId) throws SAXException { 087 // Has this system identifier been registered? 088 URL entityURL = null; 089 if (publicId != null) { 090 entityURL = getRegisteredEntities().get(publicId); 091 } 092 093 if (entityURL != null) { 094 // Obtain an InputSource for this URL. This code is based on the 095 // createInputSourceFromURL() method of Commons Digester. 096 try { 097 final URLConnection connection = entityURL.openConnection(); 098 connection.setUseCaches(false); 099 final InputStream stream = connection.getInputStream(); 100 final InputSource source = new InputSource(stream); 101 source.setSystemId(entityURL.toExternalForm()); 102 return source; 103 } catch (final IOException e) { 104 throw new SAXException(e); 105 } 106 } 107 // default processing behavior 108 return null; 109 } 110}