我应该如何使用。tasklet（）/.chunk（）成功地完成作业？

Question

我使用Spring Batch将表从源数据库克隆到目标数据库。使用joblauncher和传递参数从服务层手动启动作业。

一切都很好，但是使用当前配置（下面），在步骤描述中使用.chunk(10)时，我只克隆了10行，并且由:java.sql.sqlexception:Result set已经关闭异常引起。

@Configuration
@EnableBatchProcessing
public class DatasetProcessingContext {

    private static final String OVERRIDEN_BY_JOB_PARAMETER = null;
    private static final String DATASET_PROCESSING_STEP = "datasetProcessingStep";
    private static final String DATASET_PROCESSING_JOB = "datasetProcessingJob";

    public static final String SUBSYSTEM = "subsystem";
    public static final String SQL = "sql";
    public static final String SOURCE_DATASOURCE = "sourceDatasource";
    public static final String INSERT_QUERY = "insertQuery";
    public static final String TARGET_DATASOURCE = "targetDatasource";

    @Autowired
    @Qualifier(DEV_DATA_SOURCE)
    private DataSource devDataSource;

    //set of datasources

    @Autowired
    private PlatformTransactionManager transactionManager;

    @SuppressWarnings("MismatchedQueryAndUpdateOfCollection")
    @Autowired
    private Map<String, TableMessageDataRowMapper> tableMessageDataRowMappers;

    @SuppressWarnings("MismatchedQueryAndUpdateOfCollection")
    @Autowired
    private Map<String, TableMessageDataPreparedStatementSetter> messageDataPreparedStatementSetters;

    @Autowired
    private JobBuilderFactory jobsFactory;

    @Autowired
    private StepBuilderFactory stepsFactory;

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

    @Bean
    public JobRegistry jobRegistry() {
        return new MapJobRegistry();
    }

    @Bean
    public JobRegistryBeanPostProcessor jobRegistryBeanPostProcessor() {
        JobRegistryBeanPostProcessor postProcessor = new JobRegistryBeanPostProcessor();
        postProcessor.setJobRegistry(jobRegistry());
        return postProcessor;
    }

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

    @Bean
    public static StepScope stepScope() {
        return new StepScope();
    }

    @Bean
    @SuppressWarnings("unchecked")
    @Scope(value = "step", proxyMode = ScopedProxyMode.INTERFACES)
    public ItemStreamReader jdbcReader(@Value("#{jobParameters['" + SUBSYSTEM + "']}") String subsystem,
                                       @Value("#{jobParameters['" + SQL + "']}") String sql,
                                       @Value("#{jobParameters['" + SOURCE_DATASOURCE + "']}") String sourceDatasource) {

        JdbcCursorItemReader jdbcCursorItemReader = new JdbcCursorItemReader();
        jdbcCursorItemReader.setDataSource(getDataSourceFromEnum(TargetDataSource.valueOf(sourceDatasource)));
        jdbcCursorItemReader.setSql(sql);
        jdbcCursorItemReader.setRowMapper((RowMapper) tableMessageDataRowMappers
                .get(subsystem + TABLE_MESSAGE_DATA_ROW_MAPPER));

        return jdbcCursorItemReader;
    }

    @Bean
    @SuppressWarnings("unchecked")
    @Scope(value = "step", proxyMode = ScopedProxyMode.INTERFACES)
    public ItemWriter jdbcWriter(@Value("#{jobParameters['" + SUBSYSTEM + "']}") String subsystem,
                                 @Value("#{jobParameters['" + INSERT_QUERY + "']}") String insertQuery,
                                 @Value("#{jobParameters['" + TARGET_DATASOURCE + "']}") String targetDatasource) {

        JdbcBatchItemWriter jdbcWriter = new JdbcBatchItemWriter();
        jdbcWriter.setDataSource(getDataSourceFromEnum(TargetDataSource.valueOf(targetDatasource)));
        jdbcWriter.setSql(insertQuery);
        jdbcWriter.setItemPreparedStatementSetter(messageDataPreparedStatementSetters
                .get(subsystem + TABLE_MESSAGE_DATA_PREPARED_STATEMENT_SETTER));

        return jdbcWriter;
    }

    @Bean
    @SuppressWarnings("unchecked")
    public Step datasetProcessingStep() {

        return stepsFactory.get(DATASET_PROCESSING_STEP)
                // should I create Tasklet or chunk with some CompletionPolicy?
                .chunk(10)
                .reader(jdbcReader(OVERRIDEN_BY_JOB_PARAMETER, OVERRIDEN_BY_JOB_PARAMETER, OVERRIDEN_BY_JOB_PARAMETER))
                .writer(jdbcWriter(OVERRIDEN_BY_JOB_PARAMETER, OVERRIDEN_BY_JOB_PARAMETER, OVERRIDEN_BY_JOB_PARAMETER))
                .allowStartIfComplete(true)
                .build();
    }

    @Bean
    public Job datasetProcessingJob() {

        return jobsFactory.get(DATASET_PROCESSING_JOB).start(datasetProcessingStep()).build();
    }

Answer 1

在步骤描述中使用.chunk（new DefaultResultCompletionPolicy())适合我的情况。如果null-result-than ResultSet结束，此策略将从iscomplete（RepeatContext context,RepeatStatus result)返回true。