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具有列表的Spring Batch 3自定义编写器

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想象一下Menu.java pojo有3个字段：id，name和telephone .

我正在使用Spring Batch 3.我的处理器返回一个List . 我想在文件上写下列表中每个对象的这些值 .

如果Menu不是列表，那么这将是我的编写者类：

@Bean(name="MyWriter")
@SphynxBatchStepScope
public FlatFileItemWriter<Menu> myWriter() String fileOutputName) {

    FlatFileItemWriter<Menu> writer = new FlatFileItemWriter<Menu>();   
    writer.setResource(new FileSystemResource("test.txt")));
    DelimitedLineAggregator<Menu> delLineAgg = new DelimitedLineAggregator<Menu>();
    delLineAgg.setDelimiter("          ");
    BeanWrapperFieldExtractor<Menu> fieldExtractor = new BeanWrapperFieldExtractor<Menu>();
    fieldExtractor.setNames(new String[] {"id", "name", "telephone"});
    delLineAgg.setFieldExtractor(fieldExtractor);
    writer.setLineAggregator(delLineAgg);
    writer.setHeaderCallback(header());
    writer.setFooterCallback(footer());
    writer.setEncoding("UTF-8");

    return writer;
}

但是，如果我想将这个类转换为使用List，我该怎么办呢？

我找不到任何解决方案 . 只有这个：

Using an ItemWriter with List of Lists

但我不知道如何实现这一点 . 例如，在何处以及如何调用setDelegate方法 . 或者当我需要把我的“id”，“名字”，“电话”序列 .

请问，有没有人知道带有List的自定义Writer的代码示例？

提前致谢

spring-batch

1 回答

  • 0

    你的作家将保持原样，但被 ListUnpackingItemWriter 包裹 .

    // NOTE: this will now be the delegate used by the delegating writer.
// It will be injected to the delegating writer.
@Bean(name="MyDelegateWriter")
@SphynxBatchStepScope
public FlatFileItemWriter<Menu> myWriter(String fileOutputName) {

    FlatFileItemWriter<Menu> writer = new FlatFileItemWriter<Menu>();   
    writer.setResource(new FileSystemResource("test.txt")));
    DelimitedLineAggregator<Menu> delLineAgg = new DelimitedLineAggregator<Menu>();
    delLineAgg.setDelimiter("          ");
    BeanWrapperFieldExtractor<Menu> fieldExtractor = new BeanWrapperFieldExtractor<Menu>();
    fieldExtractor.setNames(new String[] {"id", "name", "telephone"});
    delLineAgg.setFieldExtractor(fieldExtractor);
    writer.setLineAggregator(delLineAgg);
    writer.setHeaderCallback(header());
    writer.setFooterCallback(footer());
    writer.setEncoding("UTF-8");

    return writer;
}

// NOTE: now this "MyWriter" will be used by your job
@Bean(name="MyWriter")
@SphynxBatchStepScope
public ListUnpackingItemWriter(@Qualifier("MyDelegateWriter") FlatFileItemWriter<Menu> delegate) {
    ListUnpackingItemWriter<List<Menu>> writer = new ListUnpackingItemWriter<>();
    writer.setDelegate(delegate);
    return writer;
}
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