| 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.repeat.callback; |
| 18 | |
| 19 | import org.springframework.batch.item.ItemReader; |
| 20 | import org.springframework.batch.item.ItemWriter; |
| 21 | import org.springframework.batch.repeat.ExitStatus; |
| 22 | import org.springframework.batch.repeat.RepeatCallback; |
| 23 | import org.springframework.batch.repeat.RepeatContext; |
| 24 | |
| 25 | /** |
| 26 | * Simple wrapper for two business interfaces: get the next item from a |
| 27 | * reader and apply the given writer to the result (if not null). |
| 28 | * |
| 29 | * @author Dave Syer |
| 30 | * |
| 31 | */ |
| 32 | public class ItemReaderRepeatCallback implements RepeatCallback { |
| 33 | |
| 34 | ItemReader provider; |
| 35 | |
| 36 | ItemWriter writer; |
| 37 | |
| 38 | public ItemReaderRepeatCallback(ItemReader provider, ItemWriter writer) { |
| 39 | super(); |
| 40 | this.provider = provider; |
| 41 | this.writer = writer; |
| 42 | } |
| 43 | |
| 44 | /** |
| 45 | * Default writer is null, in which case we do nothing - subclasses can |
| 46 | * extend this behaviour, but must be careful to actually exhaust the |
| 47 | * provider by calling next(). |
| 48 | * @param provider |
| 49 | */ |
| 50 | public ItemReaderRepeatCallback(ItemReader provider) { |
| 51 | this(provider, null); |
| 52 | } |
| 53 | |
| 54 | /** |
| 55 | * Use the writer to process the next item if there is one. Return the |
| 56 | * item processed, or null if nothing was available. |
| 57 | * @see org.springframework.batch.repeat.RepeatCallback#doInIteration(RepeatContext) |
| 58 | * @param context the current context. |
| 59 | * @return null if the data provider is exhausted. |
| 60 | */ |
| 61 | public ExitStatus doInIteration(RepeatContext context) throws Exception { |
| 62 | |
| 63 | ExitStatus result = ExitStatus.FINISHED; |
| 64 | Object item = provider.read(); |
| 65 | |
| 66 | if (writer != null) { |
| 67 | if (item != null) { |
| 68 | writer.write(item); |
| 69 | result = ExitStatus.CONTINUABLE; |
| 70 | } |
| 71 | item = null; |
| 72 | } |
| 73 | |
| 74 | return result; |
| 75 | } |
| 76 | |
| 77 | } |