1 /* 2 * Copyright (c) 2000, 2005, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. Oracle designates this 8 * particular file as subject to the "Classpath" exception as provided 9 * by Oracle in the LICENSE file that accompanied this code. 10 * 11 * This code is distributed in the hope that it will be useful, but WITHOUT 12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 14 * version 2 for more details (a copy is included in the LICENSE file that 15 * accompanied this code). 16 * 17 * You should have received a copy of the GNU General Public License version 18 * 2 along with this work; if not, write to the Free Software Foundation, 19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 20 * 21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 22 * or visit www.oracle.com if you need additional information or have any 23 * questions. 24 */ 25 26 // SAX entity resolver. 27 // http://www.saxproject.org 28 // No warranty; no copyright -- use this as you will. 29 // $Id: EntityResolver.java,v 1.2 2004/11/03 22:44:52 jsuttor Exp $ 30 31 package org.xml.sax; 32 33 import java.io.IOException; 34 35 36 /** 37 * Basic interface for resolving entities. 38 * 39 * <blockquote> 40 * <em>This module, both source code and documentation, is in the 41 * Public Domain, and comes with <strong>NO WARRANTY</strong>.</em> 42 * See <a href='http://www.saxproject.org'>http://www.saxproject.org</a> 43 * for further information. 44 * </blockquote> 45 * 46 * <p>If a SAX application needs to implement customized handling 47 * for external entities, it must implement this interface and 48 * register an instance with the SAX driver using the 49 * {@link org.xml.sax.XMLReader#setEntityResolver setEntityResolver} 50 * method.</p> 51 * 52 * <p>The XML reader will then allow the application to intercept any 53 * external entities (including the external DTD subset and external 54 * parameter entities, if any) before including them.</p> 55 * 56 * <p>Many SAX applications will not need to implement this interface, 57 * but it will be especially useful for applications that build 58 * XML documents from databases or other specialised input sources, 59 * or for applications that use URI types other than URLs.</p> 60 * 61 * <p>The following resolver would provide the application 62 * with a special character stream for the entity with the system 63 * identifier "http://www.myhost.com/today":</p> 64 * 65 * <pre> 66 * import org.xml.sax.EntityResolver; 67 * import org.xml.sax.InputSource; 68 * 69 * public class MyResolver implements EntityResolver { 70 * public InputSource resolveEntity (String publicId, String systemId) 71 * { 72 * if (systemId.equals("http://www.myhost.com/today")) { 73 * // return a special input source 74 * MyReader reader = new MyReader(); 75 * return new InputSource(reader); 76 * } else { 77 * // use the default behaviour 78 * return null; 79 * } 80 * } 81 * } 82 * </pre> 83 * 84 * <p>The application can also use this interface to redirect system 85 * identifiers to local URIs or to look up replacements in a catalog 86 * (possibly by using the public identifier).</p> 87 * 88 * @since 1.4, SAX 1.0 89 * @author David Megginson 90 * @see org.xml.sax.XMLReader#setEntityResolver 91 * @see org.xml.sax.InputSource 92 */ 93 public interface EntityResolver { 94 95 96 /** 97 * Allow the application to resolve external entities. 98 * 99 * <p>The parser will call this method before opening any external 100 * entity except the top-level document entity. Such entities include 101 * the external DTD subset and external parameter entities referenced 102 * within the DTD (in either case, only if the parser reads external 103 * parameter entities), and external general entities referenced 104 * within the document element (if the parser reads external general 105 * entities). The application may request that the parser locate 106 * the entity itself, that it use an alternative URI, or that it 107 * use data provided by the application (as a character or byte 108 * input stream).</p> 109 * 110 * <p>Application writers can use this method to redirect external 111 * system identifiers to secure and/or local URIs, to look up 112 * public identifiers in a catalogue, or to read an entity from a 113 * database or other input source (including, for example, a dialog 114 * box). Neither XML nor SAX specifies a preferred policy for using 115 * public or system IDs to resolve resources. However, SAX specifies 116 * how to interpret any InputSource returned by this method, and that 117 * if none is returned, then the system ID will be dereferenced as 118 * a URL. </p> 119 * 120 * <p>If the system identifier is a URL, the SAX parser must 121 * resolve it fully before reporting it to the application.</p> 122 * 123 * @param publicId The public identifier of the external entity 124 * being referenced, or null if none was supplied. 125 * @param systemId The system identifier of the external entity 126 * being referenced. 127 * @return An InputSource object describing the new input source, 128 * or null to request that the parser open a regular 129 * URI connection to the system identifier. 130 * @exception org.xml.sax.SAXException Any SAX exception, possibly 131 * wrapping another exception. 132 * @exception java.io.IOException A Java-specific IO exception, 133 * possibly the result of creating a new InputStream 134 * or Reader for the InputSource. 135 * @see org.xml.sax.InputSource 136 */ 137 public abstract InputSource resolveEntity (String publicId, 138 String systemId) 139 throws SAXException, IOException; 140 141 } 142 143 // end of EntityResolver.java