org.openide.loaders.XMLEntityResolverChain Maven / Gradle / Ivy
/*
* Sun Public License Notice
*
* The contents of this file are subject to the Sun Public License
* Version 1.0 (the "License"). You may not use this file except in
* compliance with the License. A copy of the License is available at
* http://www.sun.com/
*
* The Original Code is NetBeans. The Initial Developer of the Original
* Code is Sun Microsystems, Inc. Portions Copyright 1997-2000 Sun
* Microsystems, Inc. All Rights Reserved.
*/
package org.openide.loaders;
import java.io.*;
import java.util.*;
import org.xml.sax.*;
/**
* A utility class allowing to chain multiple EntityResolvers into one delegating
* resolution process on them.
*
* If all registered resolves are thread-safe then the implementation is thread-safe too.
*
* @author Petr Kuzel
* @version 1.0
*/
final class XMLEntityResolverChain implements EntityResolver {
/**
* Chain of resolvers contaning all EntityResolvers registred by a user.
*/
private final List resolverChain = new ArrayList(3);
/** Creates new EntityResolverChain instance */
public XMLEntityResolverChain() {
}
/**
* Add a given entity resolver to the resolver chain.
* The resolver chain is then searched by resolveEntity() method
* until some registered resolver succed.
*
* @param resolver - a non null resolver to be added
*
* @return true if successfully added
*/
public boolean addEntityResolver(EntityResolver resolver) {
if (resolver == null) throw new IllegalArgumentException();
synchronized (resolverChain) {
if (resolverChain.contains(resolver)) return false;
return resolverChain.add(resolver);
}
}
/**
* Remove a given entity resolver from the entity resolver chain.
*
* @param resolver - a non null resolver to be removed
*
* @return removed resolver instance or null if not present
*/
public EntityResolver removeEntityResolver(EntityResolver resolver) {
if (resolver == null) throw new IllegalArgumentException();
synchronized (resolverChain) {
int index = resolverChain.indexOf(resolver);
if ( index < 0 ) return null;
return (EntityResolver) resolverChain.remove(index);
}
}
/**
* Chaining resolveEntity() implementation iterating over registered resolvers.
*
* @param publicID - The public identifier of the external entity being referenced,
* or null if none was supplied.
* @param systemID - The system identifier of the external entity being referenced.
*
* @throw SAXException - Any SAX exception, possibly wrapping another exception.
* @throw IOException - A Java-specific IO exception, possibly the result of creating
* a new InputStream or Reader for the InputSource.
*
* @return An InputSource object describing the new input source,
* or null to request that the parser open a regular URI connection to the system identifier.
*/
public InputSource resolveEntity(String publicID, String systemID) throws SAXException, IOException {
// user's resolver chain
SAXException lsex = null;
IOException lioex = null;
synchronized (resolverChain) {
Iterator it = resolverChain.iterator();
while (it.hasNext()) {
EntityResolver resolver = (EntityResolver) it.next();
try {
InputSource test = resolver.resolveEntity(publicID, systemID);
if (test == null) continue;
return test;
} catch (SAXException sex) {
lsex = sex;
continue;
} catch (IOException ioex) {
lioex = ioex;
continue;
}
}
//retain the last exception for diagnostics purposes
if (lioex != null) throw lioex;
if (lsex != null) throw lsex;
//just can not resolve it
return null;
}
}
}