| 1 | /* |
| 2 | * Copyright 2006-2007 the original author or authors. |
| 3 | * |
| 4 | * Licensed under the Apache License, Version 2.0 (the "License"); |
| 5 | * you may not use this file except in compliance with the License. |
| 6 | * You may obtain a copy of the License at |
| 7 | * |
| 8 | * http://www.apache.org/licenses/LICENSE-2.0 |
| 9 | * |
| 10 | * Unless required by applicable law or agreed to in writing, software |
| 11 | * distributed under the License is distributed on an "AS IS" BASIS, |
| 12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 13 | * See the License for the specific language governing permissions and |
| 14 | * limitations under the License. |
| 15 | */ |
| 16 | |
| 17 | package org.springframework.batch.item.support; |
| 18 | |
| 19 | import java.util.Iterator; |
| 20 | |
| 21 | import org.springframework.batch.item.ItemReader; |
| 22 | import org.springframework.batch.item.ParseException; |
| 23 | import org.springframework.batch.item.UnexpectedInputException; |
| 24 | import org.springframework.util.Assert; |
| 25 | |
| 26 | /** |
| 27 | * An {@link ItemReader} that pulls data from a {@link Iterator} or |
| 28 | * {@link Iterable} using the constructors. |
| 29 | * |
| 30 | * @author Juliusz Brzostek |
| 31 | * @author Dave Syer |
| 32 | */ |
| 33 | public class IteratorItemReader<T> implements ItemReader<T> { |
| 34 | |
| 35 | /** |
| 36 | * Internal iterator |
| 37 | */ |
| 38 | private final Iterator<T> iterator; |
| 39 | |
| 40 | /** |
| 41 | * Construct a new reader from this iterable (could be a collection), by |
| 42 | * extracting an instance of {@link Iterator} from it. |
| 43 | * |
| 44 | * @param iterable in instance of {@link Iterable} |
| 45 | * |
| 46 | * @see Iterable#iterator() |
| 47 | */ |
| 48 | public IteratorItemReader(Iterable<T> iterable) { |
| 49 | Assert.notNull(iterable, "Iterable argument cannot be null!"); |
| 50 | this.iterator = iterable.iterator(); |
| 51 | } |
| 52 | |
| 53 | /** |
| 54 | * Construct a new reader from this iterator directly. |
| 55 | * @param iterator an instance of {@link Iterator} |
| 56 | */ |
| 57 | public IteratorItemReader(Iterator<T> iterator) { |
| 58 | Assert.notNull(iterator, "Iterator argument cannot be null!"); |
| 59 | this.iterator = iterator; |
| 60 | } |
| 61 | |
| 62 | /** |
| 63 | * Implementation of {@link ItemReader#read()} that just iterates over the |
| 64 | * iterator provided. |
| 65 | */ |
| 66 | @Override |
| 67 | public T read() throws Exception, UnexpectedInputException, ParseException { |
| 68 | if (iterator.hasNext()) |
| 69 | return iterator.next(); |
| 70 | else |
| 71 | return null; // end of data |
| 72 | } |
| 73 | |
| 74 | } |