xmlcatalogresolver.java

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/*
 * Copyright 2004,2005 The Apache Software Foundation.
 * 
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
 
package com.sun.org.apache.xerces.internal.util;

import java.io.IOException;

import org.xml.sax.InputSource;
import org.xml.sax.SAXException;
import org.xml.sax.ext.EntityResolver2;

import org.w3c.dom.ls.LSInput;
import org.w3c.dom.ls.LSResourceResolver;

import javax.xml.parsers.SAXParserFactory;

import com.sun.org.apache.xerces.internal.dom.DOMInputImpl;
import com.sun.org.apache.xerces.internal.jaxp.SAXParserFactoryImpl;

import com.sun.org.apache.xerces.internal.xni.XNIException;
import com.sun.org.apache.xerces.internal.xni.XMLResourceIdentifier;

import com.sun.org.apache.xerces.internal.xni.parser.XMLEntityResolver;
import com.sun.org.apache.xerces.internal.xni.parser.XMLInputSource;

import com.sun.org.apache.xml.internal.resolver.Catalog;
import com.sun.org.apache.xml.internal.resolver.CatalogManager;
import com.sun.org.apache.xml.internal.resolver.readers.OASISXMLCatalogReader;
import com.sun.org.apache.xml.internal.resolver.readers.SAXCatalogReader;

/**
 * <p>The catalog resolver handles the resolution of external
 * identifiers and URI references through XML catalogs. This
 * component supports XML catalogs defined by the
 * <a href="http://www.oasis-open.org/committees/entity/spec.html">
 * OASIS XML Catalogs Specification</a>. It encapsulates the 
 * <a href="http://xml.apache.org/commons/">XML Commons</a> resolver. 
 * An instance of this class may be registered on the parser 
 * as a SAX entity resolver, as a DOM LSResourceResolver or 
 * as an XNI entity resolver by setting the property
 * (http://apache.org/xml/properties/internal/entity-resolver).</p>
 * 
 * <p>It is intended that this class may be used standalone to perform 
 * catalog resolution outside of a parsing context. It may be shared
 * between several parsers and the application.</p>
 *
 * @author Michael Glavassevich, IBM
 *
 * @version $Id: XMLCatalogResolver.java,v 1.2.6.1 2005/09/05 08:55:10 neerajbj Exp $
 */
public class XMLCatalogResolver 
    implements XMLEntityResolver, EntityResolver2, LSResourceResolver {
    
    /** Internal catalog manager for Apache catalogs. **/
    private CatalogManager fResolverCatalogManager = null;
    
    /** Internal catalog structure. **/
    private Catalog fCatalog = null;
	
    /** An array of catalog URIs. **/
    private String [] fCatalogsList = null;

    /** 
     * Indicates whether the list of catalogs has
     * changed since it was processed.
     */
    private boolean fCatalogsChanged = true;
    
    /** Application specified prefer public setting. **/
    private boolean fPreferPublic = true;
    
    /** 
     * Indicates whether the application desires that 
     * the parser or some other component performing catalog
     * resolution should use the literal system identifier
     * instead of the expanded system identifier.
     */
    private boolean fUseLiteralSystemId = true;
    
    /**
     * <p>Constructs a catalog resolver with a default configuration.</p>
     */
    public XMLCatalogResolver () {
    	this(null, true);
    }
    
    /**
     * <p>Constructs a catalog resolver with the given
     * list of entry files.</p>
     * 
     * @param catalogs an ordered array list of absolute URIs
     */
    public XMLCatalogResolver (String [] catalogs) {
    	this(catalogs, true);
    }
    
    /**
     * <p>Constructs a catalog resolver with the given
     * list of entry files and the preference for whether
     * system or public matches are preferred.</p>
     * 
     * @param catalogs an ordered array list of absolute URIs
     * @param preferPublic the prefer public setting
     */
    public XMLCatalogResolver (String [] catalogs, boolean preferPublic) {
        init(catalogs, preferPublic);
    }
    
    /**
     * <p>Returns the initial list of catalog entry files.</p>
     * 
     * @return the initial list of catalog entry files
     */
    public final synchronized String [] getCatalogList () {
        return (fCatalogsList != null) 
            ? (String[]) fCatalogsList.clone() : null;
    }

    /**
     * <p>Sets the initial list of catalog entry files.
     * If there were any catalog mappings cached from 
     * the previous list they will be replaced by catalog 
     * mappings from the new list the next time the catalog
     * is queried.</p>
     * 
     * @param catalogs an ordered array list of absolute URIs 
     */
    public final synchronized void setCatalogList (String [] catalogs) {
        fCatalogsChanged = true;
        fCatalogsList = (catalogs != null)
            ? (String[]) catalogs.clone() : null;
    }
    
    /**
     * <p>Forces the cache of catalog mappings to be cleared.</p>
     */
    public final synchronized void clear () {
        fCatalog = null;
    }
    
    /**
     * <p>Returns the preference for whether system or public
     * matches are preferred. This is used in the absence
     * of any occurence of the <code>prefer</code> attribute
     * on the <code>catalog</code> entry of a catalog. If this
     * property has not yet been explicitly set its value is
     * <code>true</code>.</p>
     * 
     * @return the prefer public setting
     */
    public final boolean getPreferPublic () {
        return fPreferPublic;
    }
    
    /**
     * <p>Sets the preference for whether system or public
     * matches are preferred. This is used in the absence
     * of any occurence of the <code>prefer</code> attribute
     * on the <code>catalog</code> entry of a catalog.</p>
     * 
     * @param preferPublic the prefer public setting
     */
    public final void setPreferPublic (boolean preferPublic) {
        fPreferPublic = preferPublic;
        fResolverCatalogManager.setPreferPublic(preferPublic);
    }
    
    /**
     * <p>Returns the preference for whether the literal system 
     * identifier should be used when resolving system 
     * identifiers when both it and the expanded system 
     * identifier are available. If this property has not yet 
     * been explicitly set its value is <code>true</code>.</p>
     * 
     * @return the preference for using literal system identifers
     * for catalog resolution
     * 
     * @see #setUseLiteralSystemId
     */
    public final boolean getUseLiteralSystemId () {
        return fUseLiteralSystemId;
    }
    
    /**
     * <p>Sets the preference for whether the literal system 
     * identifier should be used when resolving system 
     * identifiers when both it and the expanded system 
     * identifier are available.</p>
     * 
     * <p>The literal system identifier is the URI as it was
     * provided before absolutization. It may be embedded within 
     * an entity. It may be provided externally or it may be the 
     * result of redirection. For example, redirection may 
     * have come from the protocol level through HTTP or from 
     * an application's entity resolver.</p>
     * 
     * <p>The expanded system identifier is an absolute URI 
     * which is the result of resolving the literal system 
     * identifier against a base URI.</p>
     * 
     * @param useLiteralSystemId the preference for using 
     * literal system identifers for catalog resolution
     */
    public final void setUseLiteralSystemId (boolean useLiteralSystemId) {
        fUseLiteralSystemId = useLiteralSystemId;
    }
    
    /**
     * <p>Resolves an external entity. If the entity cannot be
     * resolved, this method should return <code>null</code>. This
     * method returns an input source if an entry was found in the
     * catalog for the given external identifier. It should be
     * overrided if other behaviour is required.</p>
     * 
     * @param publicId the public identifier, or <code>null</code> if none was supplied
     * @param systemId the system identifier
     * 
     * @throws SAXException any SAX exception, possibly wrapping another exception
     * @throws IOException thrown if some i/o error occurs
     */
    public InputSource resolveEntity(String publicId, String systemId)
    	 throws SAXException, IOException {
        
        String resolvedId = null;
        if (publicId != null && systemId != null) {
            resolvedId = resolvePublic(publicId, systemId);
        }
        else if (systemId != null) {
            resolvedId = resolveSystem(systemId);
        }
        
        if (resolvedId != null) {
            InputSource source = new InputSource(resolvedId);
            source.setPublicId(publicId);
            return source;
        }  
        return null;
    }
    
     /**
      * <p>Resolves an external entity. If the entity cannot be
      * resolved, this method should return <code>null</code>. This
      * method returns an input source if an entry was found in the
      * catalog for the given external identifier. It should be
      * overrided if other behaviour is required.</p>
      * 
      * @param name the identifier of the external entity 
      * @param publicId the public identifier, or <code>null</code> if none was supplied
      * @param baseURI the URI with respect to which relative systemIDs are interpreted.
      * @param systemId the system identifier
      * 
      * @throws SAXException any SAX exception, possibly wrapping another exception
      * @throws IOException thrown if some i/o error occurs
      */
     public InputSource resolveEntity(String name, String publicId, 
         String baseURI, String systemId) throws SAXException, IOException { 
        
         String resolvedId = null;
         
         if (!getUseLiteralSystemId() && baseURI != null) {
             // Attempt to resolve the system identifier against the base URI.
             try {
                 URI uri = new URI(new URI(baseURI), systemId);
                 systemId = uri.toString();
             }
             // Ignore the exception. Fallback to the literal system identifier.
             catch (URI.MalformedURIException ex) {}
         }
         
         if (publicId != null && systemId != null) {
             resolvedId = resolvePublic(publicId, systemId);
         }
         else if (systemId != null) {
             resolvedId = resolveSystem(systemId);
         }
        
         if (resolvedId != null) {
             InputSource source = new InputSource(resolvedId);
             source.setPublicId(publicId);