java - Spring Boot + Spring Batch + Spring JPA

Question

我正在从事 Spring Batch 作业，将数据从 Sql Server 移动到 Cassandra。我正在使用 Spring Data JPA 来读取和写入数据。我已经为这两个数据库创建了实体和 JPA 存储库。

现在我不知道如何将 JpaRepostorty 与 Spring Batch ItemReader 一起使用。我在互联网上搜索并发现很少有提到使用 JpaPageItemReader 的引用文献。但这需要指定查询并配置其他详细信息。但我不知道如何使用现有的 JpaRepository 。下面是相关代码片段-

我的 SQL Server JpaRepostory -

public interface ScanJpaRepository extends JpaRepository<Scan, Integer> 
{

   @Transactional(readOnly = true)
   @Query("select s from Scan s left join fetch s.projectVersion")
   Stream<Scan> findAllScan();
}

我的 Spring 批量工作 -

@Configuration
@EnableBatchProcessing
public class SSCBatchConfigurationCassandra {

    @Autowired
    public JobBuilderFactory jobBuilderFactory;

    @Autowired
    public StepBuilderFactory stepBuilderFactory;


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


    @Bean
    public JobExplorer jobExplorer() throws Exception {
        MapJobExplorerFactoryBean jobExplorerFactory = new MapJobExplorerFactoryBean(mapJobRepositoryFactoryBean());
        jobExplorerFactory.afterPropertiesSet();
        return jobExplorerFactory.getObject();
    }

    @Bean
    public MapJobRepositoryFactoryBean mapJobRepositoryFactoryBean() {
        MapJobRepositoryFactoryBean mapJobRepositoryFactoryBean = new MapJobRepositoryFactoryBean();
        mapJobRepositoryFactoryBean.setTransactionManager(transactionManager());
        return mapJobRepositoryFactoryBean;
    }

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

    @Bean
    public JobLauncher jobLauncher() throws Exception {
        SimpleJobLauncher simpleJobLauncher = new SimpleJobLauncher();
        simpleJobLauncher.setJobRepository(jobRepository());
        return simpleJobLauncher;
    }


    @Bean
    public ItemReader<Project> reader() {
         **// how to read from ScanJpaRepository ??**
    }

    @Bean
    public CassandraItemProcessor processor() {
        return new CassandraItemProcessor();
    }

    @Bean
    public ItemWriter<CassandraProject> cqlWriter() {
         final CassandraBatchItemWriter writer = new CassandraBatchItemWriter();
         return writer;
    }



    // tag::jobstep[]
    @Bean
    public Job importUserJob(JobCompletionNotificationListener listener, Step step1) {
        return jobBuilderFactory.get("importUserJob")
                .incrementer(new RunIdIncrementer())
                .listener(listener)
                .flow(step1)
                .end()
                .build();
    }

    @Bean
    public Step step1() {
        return stepBuilderFactory.get("step1")
                .<Project, CassandraProject> chunk(100)
                .reader(reader())
                .processor(processor())
                .writer()
                .build();
    }


    // end::jobstep[]
}

更新#1: 如前所述，我将项目阅读器添加到我的批处理作业中。

@Configuration
@EnableBatchProcessing
public class FortifySSCBatchConfigurationCassandra {
   ....
   @Autowired
   public ScanItemReader itemReader;
   .....

   @Bean
   public Step step1() {
    return stepBuilderFactory.get("step1")
            .<Scan, CScan> chunk(100)
            .reader(itemReader)
            .processor(processor())
            .writer(cqlWriter())
            .build();
     }


}

我的 IDE 对此提示 -

The method reader(ItemReader<? extends Scan>) in the type SimpleStepBuilder<Scan,CScan> is not applicable for the arguments (ScanItemReader)

更新#2:

public class CassandraItemProcessor implements ItemProcessor<Scan, CScan> {


    @Override
    public CScan process(Scan s) throws Exception {


        .. 

        return new CScan();
    }

}


public class CassandraBatchItemWriter implements ItemWriter<CScan> {




    @Override
    public void write(List<? extends CScan> arg0) throws Exception {
        // TODO Auto-generated method stub

    }


}

Answer 1

你可以像这样声明你的读者

@Component
@JobScope
public class ScanItemReader extends RepositoryItemReader<Scan> {

  private final ScanJpaRepository repository;

  @Autowired
  public ScanItemReader(final ScanJpaRepository repository) {
    super();
    this.repository = repository;
  }

  @PostConstruct
  protected void init() {
    final Map<String, Sort.Direction> sorts = new HashMap<>();
    sorts.put("Your sort parameter"), Direction.ASC);// This could be any field name of your Entity class
    this.setRepository(this.repository);
    this.setSort(sorts);
    this.setMethodName(""); // You should sepcify the method which  
               //spring batch should call in your repository to fetch 
               // data and the arguments it needs needs to be  
               //specified with the below method.  
               // And this method  must return Page<T>
    this.setArguments();
  }
}

Autowiring 此读取器 bean 并在 StepBuilder 中使用它。