prepare/1_1_2/core/src/main/java/org/apache/myfaces/extensions/validator/core/metadata/extractor/DefaultComponentMetaDataExtractorFactory.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.myfaces.extensions.validator.core.metadata.extractor;

import org.apache.myfaces.extensions.validator.core.WebXmlParameter;
import org.apache.myfaces.extensions.validator.core.ExtValContext;
import org.apache.myfaces.extensions.validator.core.CustomInformation;
import org.apache.myfaces.extensions.validator.util.ClassUtils;
import org.apache.myfaces.extensions.validator.util.ExtValUtils;
import org.apache.myfaces.extensions.validator.internal.ToDo;
import org.apache.myfaces.extensions.validator.internal.Priority;
import org.apache.myfaces.extensions.validator.internal.UsageInformation;
import org.apache.myfaces.extensions.validator.internal.UsageCategory;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import java.util.ArrayList;
import java.util.List;

/**
 * This factory creates a meta-data extractor which extracts the meta-data
 * of the value binding of a component.
 * <p/>
 * order:<br/>
 * <ol>
 *   <li>configured meta-data extractor (web.xml)</li>
 *   <li>configured meta-data extractor (information provider bean)</li>
 *   <li>default implementation</li>
 * </ol>
 *
 * @author Gerhard Petracek
 * @since 1.x.1
 */
@UsageInformation(UsageCategory.INTERNAL)
public class DefaultComponentMetaDataExtractorFactory implements ComponentMetaDataExtractorFactory
{
    private final Log logger = LogFactory.getLog(getClass());

    private static MetaDataExtractor metaDataExtractor = null;

    public DefaultComponentMetaDataExtractorFactory()
    {
        if(logger.isDebugEnabled())
        {
            logger.debug(getClass().getName() + " instantiated");
        }
    }

    @ToDo(value = Priority.MEDIUM, description = "logging")
    public MetaDataExtractor create()
    {
        if (metaDataExtractor == null)
        {
            List<String> metaDataExtractorClassNames = new ArrayList<String>();

            metaDataExtractorClassNames.add(WebXmlParameter.CUSTOM_COMPONENT_META_DATA_EXTRACTOR);
            metaDataExtractorClassNames
                .add(ExtValContext.getContext().getInformationProviderBean()
                    .get(CustomInformation.COMPONENT_META_DATA_EXTRACTOR));
            metaDataExtractorClassNames.add(DefaultComponentMetaDataExtractor.class.getName());

            for (String className : metaDataExtractorClassNames)
            {
                metaDataExtractor = (MetaDataExtractor) ClassUtils.tryToInstantiateClassForName(className);

                if (metaDataExtractor != null)
                {
                    break;
                }
            }
        }

        if(logger.isTraceEnabled())
        {
            logger.trace(metaDataExtractor.getClass().getName() + " created");
        }

        return ExtValUtils.createInterceptedMetaDataExtractor(metaDataExtractor);
    }
}