BaseConfigurationXMLReader.java

/*
 * 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.configuration2;

/**
 * <p>
 * A specialized SAX2 XML parser that processes configuration objects.
 * </p>
 *
 * <p>
 * This class mimics to be a SAX compliant XML parser. It is able to iterate over the keys in a configuration object and
 * to generate corresponding SAX events. By registering a {@code ContentHandler} at an instance it is possible to
 * perform XML processing on a configuration object.
 * </p>
 */
public class BaseConfigurationXMLReader extends ConfigurationXMLReader {
    /**
     * An internally used helper class to iterate over all configuration keys ant to generate corresponding SAX events.
     */
    final class SAXConverter extends HierarchicalConfigurationConverter {
        /**
         * Callback for the end of an element.
         *
         * @param name the element name
         */
        @Override
        protected void elementEnd(final String name) {
            fireElementEnd(name);
        }

        /**
         * Callback for the start of an element.
         *
         * @param name the element name
         * @param value the element value
         */
        @Override
        protected void elementStart(final String name, final Object value) {
            fireElementStart(name, null);
            if (value != null) {
                fireCharacters(value.toString());
            }
        }
    }

    /** Stores the actual configuration. */
    private Configuration config;

    /**
     * Creates a new instance of {@code BaseConfigurationXMLReader}.
     */
    public BaseConfigurationXMLReader() {
    }

    /**
     * Creates a new instance of {@code BaseConfigurationXMLReader} and sets the configuration object to be parsed.
     *
     * @param conf the configuration to be parsed
     */
    public BaseConfigurationXMLReader(final Configuration conf) {
        this();
        setConfiguration(conf);
    }

    /**
     * Gets the actual configuration to be processed.
     *
     * @return the actual configuration
     */
    public Configuration getConfiguration() {
        return config;
    }

    /**
     * Gets the configuration to be processed.
     *
     * @return the actual configuration
     */
    @Override
    public Configuration getParsedConfiguration() {
        return getConfiguration();
    }

    /**
     * The main SAX event generation method. This element uses an internal {@code HierarchicalConfigurationConverter} object
     * to iterate over all keys in the actual configuration and to generate corresponding SAX events.
     */
    @Override
    protected void processKeys() {
        fireElementStart(getRootName(), null);
        new SAXConverter().process(getConfiguration());
        fireElementEnd(getRootName());
    }

    /**
     * Sets the configuration to be processed.
     *
     * @param conf the configuration
     */
    public void setConfiguration(final Configuration conf) {
        config = conf;
    }
}