spring-batch - Spring batch writing to different tables conditionally with ItemWriter (ItemProcessor output to Table_A if success or Table_B if fail)

Question

I am reading from source table (using JpaPagingItemReader) and passing to ItemProcessor. My requirement is if Item is processed successfully then it should write to TABLE_A and if processing failed then write to TABLE_B. I got it working, but I dont feel it as nice way. My current implementation is

// my processor
public class MyItemProcessor implements ItemProcessor<SourceEntity, BaseOutputEntity>{

    @Override
    public BaseOutputEntity process(SourceEntity input) {
       // NOTE: EntityA, EntityB both extend BaseOutputEntity
       try {
           EntityA a = callMyBusiness.method(input);
           return a;
       } catch (MyBusinessException e) {
           EntityB b = createMyFailureObj(input)
           return b;
       }
   }
}

// my itemwriter
public class MyItemWriter extends JpaItemWriter<MyBaseOutputEntity> {
    // donthing as JpaItemWriter methods will take care
}

It is doing functionally what exactly I want. One drawback of above is when I see job execution / step execution history, I can't know how many are successful or how many are failure, as it shows e.g. if 100 reads then 100 writes.

Can anyone suggest better approach. Are conditional steps useful here?

Answer 1

你可以在你的处理器上抛出一个异常，并将这个异常声明为 Skipable（如果不是，chunck 将被破坏）。

如果您实现了ItemProcessListener，您可以在 onProcessError(Entry item, Exception t) 函数上捕获无效项目并将其写入表 B。（仔细阅读文档：一些侦听器函数在事务上，其他则不是）

批处理结束时，writedItemsCount 为有效项数，skippedItemCount 为无效项数。

在不同表中写入的其他方法是将ClassifierCompositeItemWriter与 BackToBackPatternClassifier 一起使用，但您会丢失无效项目的数量。