001/* 002 * Copyright 2006-2007 the original author or authors. 003 * 004 * Licensed under the Apache License, Version 2.0 (the "License"); 005 * you may not use this file except in compliance with the License. 006 * You may obtain a copy of the License at 007 * 008 * https://www.apache.org/licenses/LICENSE-2.0 009 * 010 * Unless required by applicable law or agreed to in writing, software 011 * distributed under the License is distributed on an "AS IS" BASIS, 012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 013 * See the License for the specific language governing permissions and 014 * limitations under the License. 015 */ 016package org.springframework.batch.item.file.transform; 017 018import java.util.Collection; 019import java.util.Map; 020 021/** 022 * {@link FieldExtractor} that just returns the original item. If the item is an 023 * array or collection it will be returned as is, otherwise it is wrapped in a 024 * single element array. 025 * 026 * @author Dave Syer 027 * 028 */ 029public class PassThroughFieldExtractor<T> implements FieldExtractor<T> { 030 031 /** 032 * Get an array of fields as close as possible to the input. The result 033 * depends on the type of the input: 034 * <ul> 035 * <li>A {@link FieldSet} or array will be returned as is</li> 036 * <li>For a Collection the <code>toArray()</code> method will be used</li> 037 * <li>For a Map the <code>values()</code> will be returned as an array</li> 038 * <li>Otherwise it is wrapped in a single element array.</li> 039 * </ul> 040 * Note that no attempt is made to sort the values, so passing in an 041 * unordered collection or map is probably a bad idea. Spring often gives 042 * you an ordered Map (e.g. if extracting data from a generic query using 043 * JDBC), so check the documentation for whatever is being used to generate 044 * the input. 045 * 046 * @param item the object to convert 047 * @return an array of objects as close as possible to the original item 048 */ 049 @Override 050 public Object[] extract(T item) { 051 052 if (item.getClass().isArray()) { 053 return (Object[]) item; 054 } 055 056 if (item instanceof Collection<?>) { 057 return ((Collection<?>) item).toArray(); 058 } 059 060 if (item instanceof Map<?, ?>) { 061 return ((Map<?, ?>) item).values().toArray(); 062 } 063 064 if (item instanceof FieldSet) { 065 return ((FieldSet) item).getValues(); 066 } 067 068 return new Object[] { item }; 069 070 } 071 072}