本文介紹了Spring Batch WriterNotOpenException的處理方法，對大家解決問題具有一定的參考價值，需要的朋友們下面隨著小編來一起學習吧！
問題描述
我已經創建了一個簡單的單步Spring批處理作業，該作業從DB讀取項目、處理項目并將結果寫入CSV。
在運行時，我最終得到一個
org.springframework.batch.item.WriterNotOpenException: Writer must be open before it can be written to
相關代碼：
@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;
}
如文檔中所述，我希望生命周期事件(打開、關閉)自動得到處理，因為我是在單線程、單編寫器作業中？
Spring Batch
推薦答案
要詳細說明剩下的注釋，Spring Batch將在找到任何ItemStream實現時自動注冊它們，以便在步驟開始時自動打開它們。當使用java config時，Spring只知道返回類型。由于您返回的是ItemReader，我們不知道您的實現是否也實現了ItemStream。在使用java config時，我通常建議在已知的情況下返回實現(而不是接口)。這使得Spring可以充分反思它。因此，在本例中，返回FlatFileItemReader而不是ItemReader可以解決該問題。
這篇關于Spring Batch WriterNotOpenException的文章就介紹到這了，希望我們推薦的答案對大家有所幫助，
