/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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 org.apache.commons.configuration.resolver;

import java.io.IOException;
import java.io.InputStream;
import java.net.URL;
import java.net.URLConnection;
import java.util.HashMap;
import java.util.Map;

import org.xml.sax.EntityResolver;
import org.xml.sax.InputSource;
import org.xml.sax.SAXException;

The DefaultEntityResolver used by XML Configurations.
Author:
Commons
Configuration team
Since:
1.7
Version:
$Id: DefaultEntityResolver.java 1301991 2012-03-17 20:18:02Z sebb $/**
 * The DefaultEntityResolver used by XML Configurations.
 * @author <a
 * href="http://commons.apache.org/configuration/team-list.html">Commons
 * Configuration team</a>
 * @since 1.7
 * @version $Id: DefaultEntityResolver.java 1301991 2012-03-17 20:18:02Z sebb $
 */
public class DefaultEntityResolver implements EntityResolver, EntityRegistry
{
    
Stores a map with the registered public IDs./** Stores a map with the registered public IDs.*/
    private Map<String, URL> registeredEntities = new HashMap<String, URL>();

    

Registers the specified URL for the specified public identifier.

 This implementation maps PUBLICID's to URLs (from which the resource will be loaded). A common use case for this method is to register local URLs (possibly computed at runtime by a class loader) for DTDs and Schemas. This allows the performance advantage of using a local version without having to ensure every SYSTEM URI on every processed XML document is local. This implementation provides only basic functionality. If more sophisticated features are required, either calling XMLConfiguration.setDocumentBuilder(DocumentBuilder) to set a custom DocumentBuilder (which also can be initialized with a custom EntityResolver) or creating a custom entity resolver and registering it with the XMLConfiguration is recommended. 
Params:
publicId – Public identifier of the Entity to be resolved
entityURL – The URL to use for reading this Entity
Throws:
IllegalArgumentException – if the public ID is undefined/**
     * <p>
     * Registers the specified URL for the specified public identifier.
     * </p>
     * <p>
     * This implementation maps {@code PUBLICID}'s to URLs (from which
     * the resource will be loaded). A common use case for this method is to
     * register local URLs (possibly computed at runtime by a class loader) for
     * DTDs and Schemas. This allows the performance advantage of using a local
     * version without having to ensure every {@code SYSTEM} URI on every
     * processed XML document is local. This implementation provides only basic
     * functionality. If more sophisticated features are required, either calling
     * {@code XMLConfiguration.setDocumentBuilder(DocumentBuilder)} to set a custom
     * {@code DocumentBuilder} (which also can be initialized with a
     * custom {@code EntityResolver}) or creating a custom entity resolver
     * and registering it with the XMLConfiguration is recommended.
     * </p>
     *
     * @param publicId Public identifier of the Entity to be resolved
     * @param entityURL The URL to use for reading this Entity
     * @throws IllegalArgumentException if the public ID is undefined
     */
    public void registerEntityId(String publicId, URL entityURL)
    {
        if (publicId == null)
        {
            throw new IllegalArgumentException("Public ID must not be null!");
        }
        getRegisteredEntities().put(publicId, entityURL);
    }

    
Resolves the requested external entity. This is the default implementation of the EntityResolver interface. It checks the passed in public ID against the registered entity IDs and uses a local URL if possible. 
Params:
publicId – the public identifier of the entity being referenced
systemId – the system identifier of the entity being referenced
Throws:
SAXException – if a parsing exception occurs
Returns:
an input source for the specified entity/**
     * Resolves the requested external entity. This is the default
     * implementation of the {@code EntityResolver} interface. It checks
     * the passed in public ID against the registered entity IDs and uses a
     * local URL if possible.
     *
     * @param publicId the public identifier of the entity being referenced
     * @param systemId the system identifier of the entity being referenced
     * @return an input source for the specified entity
     * @throws org.xml.sax.SAXException if a parsing exception occurs
     */
    public InputSource resolveEntity(String publicId, String systemId)
            throws SAXException
    {
        // Has this system identifier been registered?
        URL entityURL = null;
        if (publicId != null)
        {
            entityURL = getRegisteredEntities().get(publicId);
        }

        if (entityURL != null)
        {
            // Obtain an InputSource for this URL. This code is based on the
            // createInputSourceFromURL() method of Commons Digester.
            try
            {
                URLConnection connection = entityURL.openConnection();
                connection.setUseCaches(false);
                InputStream stream = connection.getInputStream();
                InputSource source = new InputSource(stream);
                source.setSystemId(entityURL.toExternalForm());
                return source;
            }
            catch (IOException e)
            {
                throw new SAXException(e);
            }
        }
        else
        {
            // default processing behavior
            return null;
        }
    }

    
Returns a map with the entity IDs that have been registered using the registerEntityId() method. 
Returns:
a map with the registered entity IDs/**
     * Returns a map with the entity IDs that have been registered using the
     * {@code registerEntityId()} method.
     *
     * @return a map with the registered entity IDs
     */
    public Map<String, URL> getRegisteredEntities()
    {
        return registeredEntities;
    }
}