001    /*
002     * Licensed to the Apache Software Foundation (ASF) under one or more
003     * contributor license agreements.  See the NOTICE file distributed with
004     * this work for additional information regarding copyright ownership.
005     * The ASF licenses this file to You under the Apache License, Version 2.0
006     * (the "License"); you may not use this file except in compliance with
007     * the License.  You may obtain a copy of the License at
008     *
009     *      http://www.apache.org/licenses/LICENSE-2.0
010     *
011     * Unless required by applicable law or agreed to in writing, software
012     * distributed under the License is distributed on an "AS IS" BASIS,
013     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014     * See the License for the specific language governing permissions and
015     * limitations under the License.
016     */
017    package org.apache.camel.bam;
018    
019    import org.apache.camel.Exchange;
020    import org.apache.camel.Expression;
021    
022    /**
023     * @version $Revision: $
024     */
025    public abstract class ProcessExpressionSupport<T> implements Expression<Exchange> {
026    
027        public static final String PROCESS_PROPERTY = "org.apache.camel.bam.Process";
028    
029        private Class<T> type;
030    
031        protected ProcessExpressionSupport(Class<T> type) {
032            this.type = type;
033        }
034    
035        public static <T> T getProcessEntity(Exchange exchange, Class<T> type) {
036            return exchange.getProperty(PROCESS_PROPERTY, type);
037        }
038    
039        public static <T> void storeProcessEntity(Exchange exchange, T processEntity) {
040            exchange.setProperty(PROCESS_PROPERTY, processEntity);
041        }
042    
043        public Object evaluate(Exchange exchange) {
044            T processEntity = getProcessEntity(exchange, type);
045            return evaluate(exchange, processEntity);
046        }
047    
048        protected abstract Object evaluate(Exchange exchange, T processEntity);
049    }