Spring Batch WriterNotOpenException

Question

我已经创建了一个简单的单步Spring批处理作业，它从DB读取项目，处理它们，并将结果写入csv。在运行时，我最终得到一个

org.springframework.batch.item.WriterNotOpenException: Writer must be open before it can be written to

相关代码：

@Configuration
@EnableBatchProcessing
@EnableAutoConfiguration
public class CleanEmailJob {

@Autowired
private JobBuilderFactory jobBuilderFactory;

@Autowired
private StepBuilderFactory stepBuilderFactory;

@Autowired
public DataSource dataSource;

@Bean
public ResourcelessTransactionManager transactionManager() {
    return new ResourcelessTransactionManager();
}

@Bean
public MapJobRepositoryFactoryBean mapJobRepositoryFactory(ResourcelessTransactionManager txManager)
        throws Exception {
    MapJobRepositoryFactoryBean factory = new MapJobRepositoryFactoryBean(txManager);
    factory.afterPropertiesSet();
    return factory;
}

@Bean
public JobRepository jobRepository(MapJobRepositoryFactoryBean factory) throws Exception {
    return factory.getObject();
}

@Bean
public JobExplorer jobExplorer(MapJobRepositoryFactoryBean factory) {
    return new SimpleJobExplorer(factory.getJobInstanceDao(), factory.getJobExecutionDao(),
            factory.getStepExecutionDao(), factory.getExecutionContextDao());
}

@Bean
public SimpleJobLauncher jobLauncher(JobRepository jobRepository) {
    SimpleJobLauncher launcher = new SimpleJobLauncher();
    launcher.setJobRepository(jobRepository);
    return launcher;
}


@Bean
public Job cleanEmailAddressesJob() throws Exception {
    return jobBuilderFactory.get("cleanEmailAddresses")
            .incrementer(new RunIdIncrementer())
            .start(processEmailAddresses())
            .build();
}

@Bean
public Step processEmailAddresses() throws UnexpectedInputException, ParseException, Exception {
    return stepBuilderFactory.get("processAffiliates")
            .<AffiliateEmailAddress, VerifiedAffiliateEmailAddress> chunk(10)
            .reader(reader())
            .processor(processor())     
            .writer(report())
            .build();
}

@Bean
public ItemWriter<VerifiedAffiliateEmailAddress> report(){
    FlatFileItemWriter<VerifiedAffiliateEmailAddress> reportWriter = new FlatFileItemWriter<VerifiedAffiliateEmailAddress>();
    reportWriter.setResource(new ClassPathResource("report.csv"));
    DelimitedLineAggregator<VerifiedAffiliateEmailAddress> delLineAgg = new DelimitedLineAggregator<VerifiedAffiliateEmailAddress>();
    delLineAgg.setDelimiter(",");
    BeanWrapperFieldExtractor<VerifiedAffiliateEmailAddress> fieldExtractor = new BeanWrapperFieldExtractor<VerifiedAffiliateEmailAddress>();
    fieldExtractor.setNames(new String[] {"uniekNr", "reason"});
    delLineAgg.setFieldExtractor(fieldExtractor);
    reportWriter.setLineAggregator(delLineAgg);
    reportWriter.setShouldDeleteIfExists(true);
    return reportWriter;
}

正如文档中所描述的，我希望生命周期事件(打开、关闭)自动得到处理，因为我是在单线程和单写入器作业中？

Answer 1

为了详细说明留下的注释，Spring Batch将在找到任何ItemStream实现时自动注册它们，以便在步骤开始时自动打开它们。当使用java config时，Spring只知道返回类型是什么。由于您返回的是ItemReader，我们不知道您的实现是否也实现了ItemStream。当使用java config时，我通常建议返回已知的实现(而不是接口)。这使得Spring能够充分反思它。所以在这个例子中，返回FlatFileItemReader而不是ItemReader可以解决这个问题。

Answer 2

最后，结果是Spring Dev工具干扰了我的批处理应用程序。report.csv在我的类路径中，当写入报告文件时，Spring Dev Tools检测到我的类路径中的更改，并触发应用程序的重新加载，从而导致report.csv资源被关闭……

spring.devtools.restart.enabled=false

在我的application.properties中让它再次工作