/**
* Copyright Terracotta, Inc.
*
* 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 net.sf.ehcache.search.attribute;
import java.io.
Serializable;
import net.sf.ehcache.
Element;
/**
* Used to extract a search attribute value for a given cache element.<br>
* <br>
* Instances must be {@link Serializable} in order to ensure identical
* extractors are used in distributed caches
*
* @author teck
*/
public interface
AttributeExtractor extends
Serializable {
/**
* Extract the attribute value. The instance returned from this method must
* be one of:
* <ul>
* <li>java.lang.Boolean
* <li>java.lang.Byte
* <li>java.lang.Character
* <li>java.lang.Double
* <li>java.lang.Float
* <li>java.lang.Integer
* <li>java.lang.Long
* <li>java.lang.Short
* <li>java.lang.String
* <li>java.util.Date
* <li>java.sql.Date
* <li>java.lang.Enum
* </ul>
* <p/>
* NOTE: null is a legal return here as well indicating that this attribute will not be available for the given element
*
* @param element the cache element to inspect
* @param attributeName the name of the requested attribute
* @return the attribute value
* @throws AttributeExtractorException if the attribute cannot be found or extracted
*/
Object attributeFor(
Element element,
String attributeName) throws
AttributeExtractorException;
}