如何使用Spring Batch读取.csv中的动态字段长度？

public class CsvData {
    @CsvBindByName(column = "field1")
    private String field1;

    @CsvBindByName(column = "field2")
    private String field2;

    // 其他字段...

    // getter和setter方法
}

@Bean
public ItemReader<CsvData> csvItemReader() {
    FlatFileItemReader<CsvData> reader = new FlatFileItemReader<>();
    reader.setResource(new ClassPathResource("data.csv")); // 设置.csv文件的路径
    reader.setLinesToSkip(1); // 跳过文件的第一行（标题行）
    
    DefaultLineMapper<CsvData> lineMapper = new DefaultLineMapper<>();
    DelimitedLineTokenizer tokenizer = new DelimitedLineTokenizer();
    tokenizer.setNames("field1", "field2"); // 设置字段的名称
    
    lineMapper.setLineTokenizer(tokenizer);
    lineMapper.setFieldSetMapper(new BeanWrapperFieldSetMapper<>() {{
        setTargetType(CsvData.class);
    }});
    
    reader.setLineMapper(lineMapper);
    
    return reader;
}

@Bean
public ItemProcessor<CsvData, CsvData> csvItemProcessor() {
    return item -> {
        // 处理动态字段长度
        String field1 = item.getField1();
        String field2 = item.getField2();
        
        // 其他处理逻辑...
        
        return item;
    };
}

@Bean
public ItemWriter<CsvData> csvItemWriter() {
    return items -> {
        // 写入目标位置的逻辑...
    };
}

@Bean
public Job csvProcessingJob(JobBuilderFactory jobBuilderFactory, Step csvProcessingStep) {
    return jobBuilderFactory.get("csvProcessingJob")
            .incrementer(new RunIdIncrementer())
            .flow(csvProcessingStep)
            .end()
            .build();
}

@Bean
public Step csvProcessingStep(StepBuilderFactory stepBuilderFactory, ItemReader<CsvData> csvItemReader,
                              ItemProcessor<CsvData, CsvData> csvItemProcessor, ItemWriter<CsvData> csvItemWriter) {
    return stepBuilderFactory.get("csvProcessingStep")
            .<CsvData, CsvData>chunk(10)
            .reader(csvItemReader)
            .processor(csvItemProcessor)
            .writer(csvItemWriter)
            .build();
}