| 1 | package org.springframework.batch.core.step.item; |
| 2 | |
| 3 | import org.springframework.batch.item.ExecutionContext; |
| 4 | import org.springframework.batch.item.ItemReader; |
| 5 | import org.springframework.batch.item.ItemStream; |
| 6 | import org.springframework.batch.item.ItemStreamException; |
| 7 | import org.springframework.batch.item.ParseException; |
| 8 | import org.springframework.batch.item.UnexpectedInputException; |
| 9 | |
| 10 | /** |
| 11 | * Convenience wrapper for an ItemReader that keeps track of how many items |
| 12 | * were successfully processed. |
| 13 | */ |
| 14 | class OffsetItemReader<T> implements ItemReader<T>, ItemStream { |
| 15 | |
| 16 | private static final String OFFSET_KEY = FaultTolerantStepFactoryBean.class.getName()+".OFFSET_KEY"; |
| 17 | private final ItemReader<? extends T> itemReader; |
| 18 | private int offset; |
| 19 | |
| 20 | /** |
| 21 | * @param itemReader |
| 22 | */ |
| 23 | public OffsetItemReader(ItemReader<? extends T> itemReader) { |
| 24 | this.itemReader = itemReader; |
| 25 | } |
| 26 | |
| 27 | public T read() throws Exception, UnexpectedInputException, ParseException { |
| 28 | for (int i=0; i<offset; i++) { |
| 29 | // Discard items that are already processed |
| 30 | itemReader.read(); |
| 31 | } |
| 32 | offset = 0; |
| 33 | return itemReader.read(); |
| 34 | } |
| 35 | |
| 36 | /** |
| 37 | * {@inheritDoc} |
| 38 | */ |
| 39 | public void close() throws ItemStreamException { |
| 40 | } |
| 41 | |
| 42 | /** |
| 43 | * {@inheritDoc} |
| 44 | */ |
| 45 | public void open(ExecutionContext executionContext) throws ItemStreamException { |
| 46 | offset = executionContext.getInt(OFFSET_KEY, 0); |
| 47 | } |
| 48 | |
| 49 | /** |
| 50 | * {@inheritDoc} |
| 51 | */ |
| 52 | public void update(ExecutionContext executionContext) throws ItemStreamException { |
| 53 | executionContext.putInt(OFFSET_KEY, offset); |
| 54 | } |
| 55 | |
| 56 | } |