001/*
002 * Copyright 2002-2013 the original author or authors.
003 * 
004 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with
005 * the License. You may obtain a copy of the License at
006 * 
007 * https://www.apache.org/licenses/LICENSE-2.0
008 * 
009 * Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on
010 * an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the
011 * specific language governing permissions and limitations under the License.
012 */
013package org.springframework.batch.item;
014
015import org.springframework.core.convert.converter.Converter;
016import org.springframework.expression.Expression;
017import org.springframework.expression.ExpressionParser;
018import org.springframework.expression.spel.standard.SpelExpressionParser;
019
020/**
021 * An implementation of {@link Converter} that uses SpEL to map a Value to a key
022 * @author David Turanski
023 * @since 2.2
024 */
025public class SpELItemKeyMapper<K,V> implements Converter<V,K> {
026        private final ExpressionParser parser = new SpelExpressionParser();
027        private final Expression parsedExpression;
028        
029        public SpELItemKeyMapper(String keyExpression) {
030                parsedExpression =  parser.parseExpression(keyExpression);
031        }
032        /* (non-Javadoc)
033         * @see org.springframework.batch.item.ItemKeyMapper#mapKey(java.lang.Object)
034         */
035        @SuppressWarnings("unchecked")
036        @Override
037        public K convert(V item) {
038                return (K) parsedExpression.getValue(item);
039        }
040}