如何在 Spring Batch 中使用 HibernateCursorItemReader

Question

在 spring 批处理作业中，我有一个步骤，我想使用 Hibernate 从数据库中按块读取数据，处理它并将其写回数据库。 现在我在设置阅读器时遇到了一些麻烦：

@EnableBatchProcessing
@Configuration
@ComponentScan(basePackages = {"com.x.y.z.database", "com.x.y.p.database"}, excludeFilters={
        @ComponentScan.Filter(type= FilterType.ASSIGNABLE_TYPE, value=ConfigHelperMail.class)})
@EntityScan(basePackages = {"com.x.y.z.database", "com.x.y.p.database"})
@EnableJpaRepositories({"com.x.y.z.database", "com.x.y.p.database"})
public class BatchConfiguration {
    @Autowired
    public JobBuilderFactory jobs;
    @Bean
    public Job job(CustomJobListener listener,
                     @Qualifier("step1") Step step1,
                     @Qualifier("step2") Step step2,
                     @Qualifier("step3") Step step3) {
        return jobs.get("SimpleJobName")
                .incrementer(new RunIdIncrementer())
                .preventRestart()
                .listener(listener)
                .start(step1)
                .next(step2)
                .next(step3)
                .build();
    }
}

在step1 writer 中，我使用 Hibernate 将数据保存到数据库中：

@Entity
@Table(name = "tmp_z_stepone")
public class StepOneEntity {
    @Id
    @Column(name = "reference")
    private String reference;
    /** Other properties and getters and setters **/
}

@Component
public class StepOneWriter implements ItemWriter<StepOneEntity> {
    @Autowired
    private StepOneService stepOneService;
    @Override
    public void write (List<? extends StepOneEntity> items) throws WriterException {
        stepOneService.saveMany(items);
    }
}

StepOneService使用@Service注释，它使用扩展CrudRepository<StepOneEntity, String>的 DAO 接口，其saveMany方法仅使用CrudRepository<StepOneEntity, String>的save方法。

第2步

@Component
public class StepOne {
    @Autowired
    private StepTwoReader reader;
    @Autowired
    private StepTwoProcessor processor;
    @Autowired
    private StepTwoWriter writer;
    @Bean
    @JobScope
    @Qualifier("step2")
    public Step step2() throws ReaderException {
        return stepBuilderFactory.get("step2")
                .<StepOneEntity, StepTwoEntity>chunk(10)
                .reader(reader.read())
                .processor(processor)
                .writer(writer)
                .build();
    }
}

@Component
public class StepTwoReader {
    public ItemReader<OutputControleFormat> read () throws ReaderException {
        HibernateCursorItemReader itemReader = new HibernateCursorItemReader();
        itemReader.setQueryString("from tmp_z_stepone");
        itemReader.setUseStatelessSession(true);
        return itemReader;
    }
}

我想我正在执行一些会话/ORM 配置，但我不知道在哪里，错误如下：

org.springframework.batch.item.ItemStreamException: Failed to initialize the reader
    at org.springframework.batch.item.support.AbstractItemCountingItemStreamItemReader.open(AbstractItemCountingItemStreamItemReader.java:147) ~[spring-batch-infrastructure-3.0.8.RELEASE.jar:3.0.8.RELEASE]
    at org.springframework.batch.item.support.CompositeItemStream.open(CompositeItemStream.java:96) ~[spring-batch-infrastructure-3.0.8.RELEASE.jar:3.0.8.RELEASE]
    at org.springframework.batch.core.step.item.ChunkMonitor.open(ChunkMonitor.java:114) ~[spring-batch-core-3.0.8.RELEASE.jar:3.0.8.RELEASE]
    at org.springframework.batch.item.support.CompositeItemStream.open(CompositeItemStream.java:96) ~[spring-batch-infrastructure-3.0.8.RELEASE.jar:3.0.8.RELEASE]
    at org.springframework.batch.core.step.tasklet.TaskletStep.open(TaskletStep.java:310) ~[spring-batch-core-3.0.8.RELEASE.jar:3.0.8.RELEASE]
    at org.springframework.batch.core.step.AbstractStep.execute(AbstractStep.java:197) ~[spring-batch-core-3.0.8.RELEASE.jar:3.0.8.RELEASE]
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_92]
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_92]
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_92]
    at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_92]
    at org.springframework.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:333) [spring-aop-4.3.13.RELEASE.jar:4.3.13.RELEASE]
    at org.springframework.aop.framework.ReflectiveMethodInvocation.invokeJoinpoint(ReflectiveMethodInvocation.java:190) [spring-aop-4.3.13.RELEASE.jar:4.3.13.RELEASE]
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:157) [spring-aop-4.3.13.RELEASE.jar:4.3.13.RELEASE]
    at org.springframework.aop.support.DelegatingIntroductionInterceptor.doProceed(DelegatingIntroductionInterceptor.java:133) [spring-aop-4.3.13.RELEASE.jar:4.3.13.RELEASE]
    at org.springframework.aop.support.DelegatingIntroductionInterceptor.invoke(DelegatingIntroductionInterceptor.java:121) [spring-aop-4.3.13.RELEASE.jar:4.3.13.RELEASE]
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179) [spring-aop-4.3.13.RELEASE.jar:4.3.13.RELEASE]
    at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:213) [spring-aop-4.3.13.RELEASE.jar:4.3.13.RELEASE]
    at com.sun.proxy.$Proxy110.execute(Unknown Source) [na:na]
    at org.springframework.batch.core.job.SimpleStepHandler.handleStep(SimpleStepHandler.java:148) [spring-batch-core-3.0.8.RELEASE.jar:3.0.8.RELEASE]
    at org.springframework.batch.core.job.AbstractJob.handleStep(AbstractJob.java:392) [spring-batch-core-3.0.8.RELEASE.jar:3.0.8.RELEASE]
    at org.springframework.batch.core.job.SimpleJob.doExecute(SimpleJob.java:135) [spring-batch-core-3.0.8.RELEASE.jar:3.0.8.RELEASE]
    at org.springframework.batch.core.job.AbstractJob.execute(AbstractJob.java:306) [spring-batch-core-3.0.8.RELEASE.jar:3.0.8.RELEASE]
    at org.springframework.batch.core.launch.support.SimpleJobLauncher$1.run(SimpleJobLauncher.java:135) [spring-batch-core-3.0.8.RELEASE.jar:3.0.8.RELEASE]
    at org.springframework.core.task.SyncTaskExecutor.execute(SyncTaskExecutor.java:50) [spring-core-4.3.13.RELEASE.jar:4.3.13.RELEASE]
    at org.springframework.batch.core.launch.support.SimpleJobLauncher.run(SimpleJobLauncher.java:128) [spring-batch-core-3.0.8.RELEASE.jar:3.0.8.RELEASE]
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_92]
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_92]
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_92]
    at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_92]
    at org.springframework.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:333) [spring-aop-4.3.13.RELEASE.jar:4.3.13.RELEASE]
    at org.springframework.aop.framework.ReflectiveMethodInvocation.invokeJoinpoint(ReflectiveMethodInvocation.java:190) [spring-aop-4.3.13.RELEASE.jar:4.3.13.RELEASE]
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:157) [spring-aop-4.3.13.RELEASE.jar:4.3.13.RELEASE]
    at org.springframework.batch.core.configuration.annotation.SimpleBatchConfiguration$PassthruAdvice.invoke(SimpleBatchConfiguration.java:127) [spring-batch-core-3.0.8.RELEASE.jar:3.0.8.RELEASE]
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179) [spring-aop-4.3.13.RELEASE.jar:4.3.13.RELEASE]
    at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:213) [spring-aop-4.3.13.RELEASE.jar:4.3.13.RELEASE]
    at com.sun.proxy.$Proxy107.run(Unknown Source) [na:na]
    at org.springframework.boot.autoconfigure.batch.JobLauncherCommandLineRunner.execute(JobLauncherCommandLineRunner.java:211) [spring-boot-autoconfigure-1.5.9.RELEASE.jar:1.5.9.RELEASE]
    at org.springframework.boot.autoconfigure.batch.JobLauncherCommandLineRunner.executeLocalJobs(JobLauncherCommandLineRunner.java:227) [spring-boot-autoconfigure-1.5.9.RELEASE.jar:1.5.9.RELEASE]
    at org.springframework.boot.autoconfigure.batch.JobLauncherCommandLineRunner.launchJobFromProperties(JobLauncherCommandLineRunner.java:123) [spring-boot-autoconfigure-1.5.9.RELEASE.jar:1.5.9.RELEASE]
    at org.springframework.boot.autoconfigure.batch.JobLauncherCommandLineRunner.run(JobLauncherCommandLineRunner.java:117) [spring-boot-autoconfigure-1.5.9.RELEASE.jar:1.5.9.RELEASE]
    at org.springframework.boot.SpringApplication.callRunner(SpringApplication.java:732) [spring-boot-1.5.9.RELEASE.jar:1.5.9.RELEASE]
    at org.springframework.boot.SpringApplication.callRunners(SpringApplication.java:716) [spring-boot-1.5.9.RELEASE.jar:1.5.9.RELEASE]
    at org.springframework.boot.SpringApplication.afterRefresh(SpringApplication.java:703) [spring-boot-1.5.9.RELEASE.jar:1.5.9.RELEASE]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:304) [spring-boot-1.5.9.RELEASE.jar:1.5.9.RELEASE]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1118) [spring-boot-1.5.9.RELEASE.jar:1.5.9.RELEASE]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1107) [spring-boot-1.5.9.RELEASE.jar:1.5.9.RELEASE]
    at com.cdn.oxc.signature.ApplicationConfig.main(ApplicationConfig.java:33) [classes/:na]
Caused by: java.lang.NullPointerException: null
    at org.springframework.batch.item.database.HibernateItemReaderHelper.createQuery(HibernateItemReaderHelper.java:141) ~[spring-batch-infrastructure-3.0.8.RELEASE.jar:3.0.8.RELEASE]
    at org.springframework.batch.item.database.HibernateItemReaderHelper.getForwardOnlyCursor(HibernateItemReaderHelper.java:125) ~[spring-batch-infrastructure-3.0.8.RELEASE.jar:3.0.8.RELEASE]
    at org.springframework.batch.item.database.HibernateCursorItemReader.doOpen(HibernateCursorItemReader.java:185) ~[spring-batch-infrastructure-3.0.8.RELEASE.jar:3.0.8.RELEASE]
    at org.springframework.batch.item.support.AbstractItemCountingItemStreamItemReader.open(AbstractItemCountingItemStreamItemReader.java:144) ~[spring-batch-infrastructure-3.0.8.RELEASE.jar:3.0.8.RELEASE]
    ... 46 common frames omitted

Answer 1

HibernateCursorItemReader实现了InitializingBean接口，这意味着如果将Spring声明为bean， afterPropertiesSet在容器初始化时调用afterPropertiesSet 。 但是，在您的情况下， HibernateCursorItemReader在应用程序上下文中未声明为Bean，而是包装在一个类（ StepTwoReader ）中，然后使用reader.read()创建。

如果使用read方法中的当前代码将HibernateCursorItemReader声明为Bean，则应获得IllegalStateException并显示消息：“必须提供SessionFactory”。 实际上，您实际上需要为Hibernate阅读器配置一个SessionFactory 。

另一个选择是使用HibernateCursorItemReaderBuilder ，它将确保阅读器已正确配置。

Answer 2

@StepScope
@Slf4j
@Component
public class CursorItemReader extends HibernateCursorItemReader<ItemEntity> {


    public CursorItemReader(EntityManagerFactory entityManagerFactory,
                            @Value("#{stepExecution}")StepExecution stepExecution) {

       
        this.setName("CursorItemReader");
        this.setSessionFactory(entityManagerFactory.createEntityManager().unwrap(org.hibernate.Session.class).getSessionFactory());
        this.setQueryString("from ItemEntity");
        this.setUseStatelessSession(true);
        this.setFetchSize(5);
    }

    @Override
    public ItemEntity read() throws Exception {
        ItemEntity item = this.doRead();
        return item;
    }

}

您也可以参考- https://docs.spring.io/spring-batch/docs/current/reference/html/readersAndWriters.html#HibernateCursorItemReader