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.configuration.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 1301991 2012-03-17 20:18:02Z sebb $ 037 */ 038public class DefaultEntityResolver implements EntityResolver, EntityRegistry 039{ 040 /** Stores a map with the registered public IDs.*/ 041 private Map<String, URL> registeredEntities = new HashMap<String, URL>(); 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 public void registerEntityId(String publicId, 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 public InputSource resolveEntity(String publicId, String systemId) 086 throws SAXException 087 { 088 // Has this system identifier been registered? 089 URL entityURL = null; 090 if (publicId != null) 091 { 092 entityURL = getRegisteredEntities().get(publicId); 093 } 094 095 if (entityURL != null) 096 { 097 // Obtain an InputSource for this URL. This code is based on the 098 // createInputSourceFromURL() method of Commons Digester. 099 try 100 { 101 URLConnection connection = entityURL.openConnection(); 102 connection.setUseCaches(false); 103 InputStream stream = connection.getInputStream(); 104 InputSource source = new InputSource(stream); 105 source.setSystemId(entityURL.toExternalForm()); 106 return source; 107 } 108 catch (IOException e) 109 { 110 throw new SAXException(e); 111 } 112 } 113 else 114 { 115 // default processing behavior 116 return null; 117 } 118 } 119 120 /** 121 * Returns a map with the entity IDs that have been registered using the 122 * {@code registerEntityId()} method. 123 * 124 * @return a map with the registered entity IDs 125 */ 126 public Map<String, URL> getRegisteredEntities() 127 { 128 return registeredEntities; 129 } 130}