Spring Batch: org.springframework.batch.item.ReaderNotOpenException: Reader must be open before it can be read

Question

I read SO related questions but the solutions don\'t work for me.

I get the org.springframework.batch.item.ReaderNotOpenException: Reader must be open before i

Answer 1

Since you put the reader in StepScope, the bean return type should be the implementing type FlatFileItemReader:

@Bean
@StepScope
public FlatFileItemReader reader(@Value("#{jobParameters[inputZipfile]}") String inputZipfile) {
            ...
            return reader;
}

If you specify the interface, the Spring proxy only has access to the methods and annotations specified on the interface ItemReader and is missing important annotations. There is also a warning (with a typo) in the logs:

2015-05-07 10:40:22,733 WARN  [main] org.springframework.batch.item.ItemReader is an interface.  The implementing class will not be queried for annotation based listener configurations.  If using @StepScope on a @Bean method, be sure to return the implementing class so listner annotations can be used.
2015-05-07 10:40:22,748 WARN  [main] org.springframework.batch.item.ItemReader is an interface.  The implementing class will not be queried for annotation based listener configurations.  If using @StepScope on a @Bean method, be sure to return the implementing class so listner annotations can be used. 

Currently the Spring Boot Batch example is also returning the ItemReader, so I guess other people will struggle with the same issues.