EntityResolverWrapper


1   /*
2    * The Apache Software License, Version 1.1
3    *
4    *
5    * Copyright (c) 2001, 2002 The Apache Software Foundation.  
6    * All rights reserved.
7    *
8    * Redistribution and use in source and binary forms, with or without
9    * modification, are permitted provided that the following conditions
10   * are met:
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12   * 1. Redistributions of source code must retain the above copyright
13   *    notice, this list of conditions and the following disclaimer. 
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15   * 2. Redistributions in binary form must reproduce the above copyright
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17   *    the documentation and/or other materials provided with the
18   *    distribution.
19   *
20   * 3. The end-user documentation included with the redistribution,
21   *    if any, must include the following acknowledgment:  
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27   * 4. The names "Xerces" and "Apache Software Foundation" must
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50   * This software consists of voluntary contributions made by many
51   * individuals on behalf of the Apache Software Foundation and was
52   * originally based on software copyright (c) 1999, International
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57  
58  package com.sun.org.apache.xerces.internal.util;
59  
60  import java.io.InputStream  ;
61  import java.io.IOException  ;
62  import java.io.Reader  ;
63  
64  import com.sun.org.apache.xerces.internal.xni.XNIException;
65  import com.sun.org.apache.xerces.internal.xni.XMLResourceIdentifier;
66  import com.sun.org.apache.xerces.internal.xni.parser.XMLEntityResolver;
67  import com.sun.org.apache.xerces.internal.xni.parser.XMLInputSource;
68  
69  import org.xml.sax.EntityResolver  ;
70  import org.xml.sax.InputSource  ;
71  import org.xml.sax.SAXException  ;
72  
73  /**
74   * This class wraps a SAX entity resolver in an XNI entity resolver.
75   *
76   * @see EntityResolver
77   *
78   * @author Andy Clark, IBM
79   * 
80   * @version $Id: EntityResolverWrapper.java,v 1.5 2002/04/19 17:15:37 sandygao Exp $
81   */
82  public class EntityResolverWrapper
83      implements XMLEntityResolver {
84  
85      //
86      // Data
87      //
88  
89      /** The SAX entity resolver. */
90      protected EntityResolver fEntityResolver;
91  
92      //
93      // Constructors
94      //
95  
96      /** Default constructor. */
97      public EntityResolverWrapper() {}
98  
99      /** Wraps the specified SAX entity resolver. */
100     public EntityResolverWrapper(EntityResolver entityResolver) {
101         setEntityResolver(entityResolver);
102     } // <init>(EntityResolver)
103 
104     //
105     // Public methods
106     //
107 
108     /** Sets the SAX entity resolver. */
109     public void setEntityResolver(EntityResolver entityResolver) {
110         fEntityResolver = entityResolver;
111     } // setEntityResolver(EntityResolver)
112 
113     /** Returns the SAX entity resolver. */
114     public EntityResolver getEntityResolver() {
115         return fEntityResolver;
116     } // getEntityResolver():EntityResolver
117 
118     //
119     // XMLEntityResolver methods
120     //
121     
122     /**
123      * Resolves an external parsed entity. If the entity cannot be
124      * resolved, this method should return null.
125      *
126      * @param resourceIdentifier    contains the physical co-ordinates of the resource to be resolved
127      *
128      * @throws XNIException Thrown on general error.
129      * @throws IOException  Thrown if resolved entity stream cannot be
130      *                      opened or some other i/o error occurs.
131      */
132     public XMLInputSource resolveEntity(XMLResourceIdentifier resourceIdentifier)
133         throws XNIException, IOException   {
134 
135         // When both pubId and sysId are null, the user's entity resolver
136         // can do nothing about it. We'd better not bother calling it.
137         // This happens when the resourceIdentifier is a GrammarDescription,
138         // which describes a schema grammar of some namespace, but without
139         // any schema location hint. -Sg
140         String   pubId = resourceIdentifier.getPublicId();
141         String   sysId = resourceIdentifier.getExpandedSystemId();
142         if (pubId == null && sysId == null)
143             return null;
144 
145         // resolve entity using SAX entity resolver
146         if (fEntityResolver != null && resourceIdentifier != null) {
147             try {
148                 InputSource inputSource = fEntityResolver.resolveEntity(pubId, sysId);
149                 if (inputSource != null) {
150                     String   publicId = inputSource.getPublicId();
151                     String   systemId = inputSource.getSystemId();
152                     String   baseSystemId = resourceIdentifier.getBaseSystemId();
153                     InputStream   byteStream = inputSource.getByteStream();
154                     Reader   charStream = inputSource.getCharacterStream();
155                     String   encoding = inputSource.getEncoding();
156                     XMLInputSource xmlInputSource =
157                         new XMLInputSource(publicId, systemId, baseSystemId);
158                     xmlInputSource.setByteStream(byteStream);
159                     xmlInputSource.setCharacterStream(charStream);
160                     xmlInputSource.setEncoding(encoding);
161                     return xmlInputSource;
162                 }
163             }
164 
165             // error resolving entity
166             catch (SAXException   e) {
167                 Exception   ex = e.getException();
168                 if (ex == null) {
169                     ex = e;
170                 }
171                 throw new XNIException(ex);
172             }
173         }
174 
175         // unable to resolve entity
176         return null;
177 
178     } // resolveEntity(String,String,String):XMLInputSource
179 }
180
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