如何为我的 Spring 批处理项目中的每个步骤创建自定义 ItemReader

Question

我正在尝试在每个步骤中使用自定义 reader、处理器和编写器：

    public Step step1(StepBuilderFactory factory,
                         ItemReader reader,
                         ExpireAssessmentWriter writer,
                         AssessmentItemProcessor processor,
                         PlatformTransactionManager platformTransactionManager){
        return stepBuilderFactory.get("step1")
                .transactionManager(platformTransactionManager)
                .<Assessment,Assessment>chunk(10)
                .reader(reader)
                .processor(processor)
                .writer(writer)
                .build();
    }

    //update aggregate balance table
    @Bean
    public Step step2(StepBuilderFactory factory,
                      ItemReader reader,
                      BalanceItemWriter writer,
                      BalanceProcessor processor,
                      PlatformTransactionManager platformTransactionManager){
        return stepBuilderFactory.get("step2")
                .transactionManager(platformTransactionManager)
                .<Assessment,Assessment>chunk(10)
                .reader(reader)
                .processor(processor)
                .writer(writer)
                .build();
    }

    
    @Bean
    public Step step3(StepBuilderFactory factory,
                      ItemReader<Assessment> reader,
                      CustomWriter3 writer,
                      CustomItemProcessor3 processor,
                      PlatformTransactionManager platformTransactionManager){
        return stepBuilderFactory.get("step3")
                .transactionManager(platformTransactionManager)
                .<Assessment,Assessment>chunk(10)
                .reader(reader)
                .processor(processor)
                .writer(writer)
                .build();
    }

第一步工作正常，但只有当我把这个 reader 留在同一个 class:

    private static final String READER_QUERY = "SELECT * FROM TABLE1 WHERE COLUMN='TEST'";

@Bean
    public JdbcCursorItemReader<Assessment> reader(DataSource dataSource) {
        return new JdbcCursorItemReaderBuilder<Assessment>()
                .dataSource(dataSource)
                .name("AssessmentUtilityReader")
                .sql(READER_QUERY)
                .rowMapper(new AssessmentMapper())
                .build();
    }

我如何为每个将读取其自己的查询的步骤创建自定义 reader？

我可以创建一个扩展 JdbcCursorItemReader 的自定义 reader returns 同样的代码片段？ :


@Bean
    public JdbcCursorItemReader<Assessment> reader(DataSource dataSource) {
        return new JdbcCursorItemReaderBuilder<Assessment>()
                .dataSource(dataSource)
                .name("AssessmentUtilityReader")
                .sql(READER_QUERY)
                .rowMapper(new AssessmentMapper())
                .build();
    }
    ```

Answer 1

由于所有步骤的项目类型都相同，您可以创建一个接受查询的方法和 returns 一个项目 reader:

public JdbcCursorItemReader<Assessment> getReader(DataSource dataSource, String query) {
   return new JdbcCursorItemReaderBuilder<Assessment>()
            .dataSource(dataSource)
            .name("AssessmentUtilityReader") // can be passed as a parameter as well
            .sql(query)
            .rowMapper(new AssessmentMapper())
            .build();
}

然后在每个步骤定义中调用此方法，并为每个步骤传递所需的查询。

如何为我的 Spring 批处理项目中的每个步骤创建自定义 ItemReader

How do I create custom ItemReader for each step in my Spring Batch project

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