Springbatch从两个数据库表中读取数据并写入XML文件

您的行为绝对是正常的，因为对于您阅读的每个项目，您都有一个Settlement对象，其中包含一个Header和一个Detail。您的问题是批处理领域中的常见问题，在Spring Batch中，它被称为“基于查询的ItemReaders的驱动”，您可以在这里找到更多有关该问题的信息。

按照这种模式解决问题的方式是，创建一个仅返回SettlementHeader项目的读取器，并添加一个接受每个Item（SettlementHeader）的处理器，并通过查询数据库中的Settlement Details将其转换为Settlement对象。

这是我的解决方案：

步骤项目

@Bean(destroyMethod = "")
public JdbcCursorItemReader<SettlementHeader> settlementHeaderReader(DataSource dataSource) {
    JdbcCursorItemReader<SettlementHeader> ItemReader = new JdbcCursorItemReader<>();
    ItemReader.setDataSource(dataSource);
    ItemReader.setSql("SELECT DISTINCT A.FILE_ID, A.PROCESS_DATE, A.FILE_NAME, A.SERVICE, A.SUB_SERVICE, A.SENDER, A.RUN_MODE, A.CURRENCY, A.PROCESS_WINDOW_NO"
                        + "FROM SETTLEMENT_HEADER A");
    ItemReader.setRowMapper(new SettlementHeaderRowMapper());
    return ItemReader;
}


@Bean
public ItemProcessor<SettlementHeader, Settlement> settlementHeaderProcessor(JdbcTemplate jdbcTemplate){

    return item -> {
        List<SettlementDetail> settlementDetails = jdbcTemplate.query("SELECT B.RECORD_SEQ_NO, B.AGENT_FROM,B.AGENT_TO,B.SETTLE_VOLUME,B.AMOUNT_CURRENCY,B.SETTLE_AMOUNT " +
                "  FROM SETTLEMENT_DETAIL B WHERE ? = B.FILE_ID",
                new Object[]{item.getFileId()},
                new SettlementDetailRowMapper());

        Settlement settlement = new Settlement ();

        List<SettlementHeader> settlementheader= new ArrayList<SettlementHeader>();
        settlementheader.add(item);

        settlement.setSettlementDetails(settlementDetails);
        settlement.setSettlementHeader(settlementheader);

        return settlement;
    };
}

// Your writer should stay the same
@Bean(destroyMethod = "")
public StaxEventItemWriter<Settlement> settlementwriter() throws Exception {
    StaxEventItemWriter<Settlement> ItemWriter = new StaxEventItemWriter<>();
    ItemWriter.setResource(new FileSystemResource(".../Settlement.xml"));
    ItemWriter.setRootTagName("Settlement");
    ItemWriter.setMarshaller(marshaller);
    ItemWriter.afterPropertiesSet();
    return ItemWriter;
}

行映射器

public class SettlementHeaderRowMapper implements RowMapper<SettlementHeader> {
@Override
public SettlementHeader mapRow(ResultSet rs, int i) throws SQLException {
    SettlementHeader header = new SettlementHeader();

    header.setFileId(rs.getInt("FILE_ID"));
    header.setPrcDte(rs.getDate("PROCESS_DATE").toLocalDate());
    header.setFilename(rs.getString("FILE_NAME"));
    header.setService(rs.getString("SERVICE"));
    header.setSubServ(rs.getString("SUB_SERVICE"));
    header.setSender(rs.getInt("SENDER"));
    header.setRunMode(rs.getString("RUN_MODE"));
    header.setCurrency(rs.getString("CURRENCY"));
    header.setPrcWndwNum(rs.getInt("PROCESS_WINDOW_NO"));

    return header;
}

}

public class SettlementDetailRowMapper implements RowMapper<SettlementDetail> {
@Override
public SettlementDetail mapRow(ResultSet rs, int i) throws SQLException {
    SettlementDetail detail = new SettlementDetail();
    SttlAmt sttlAmt = new SttlAmt();

    detail.setSeqNumb(rs.getInt("RECORD_SEQ_NO"));
    detail.setAgntFrm(rs.getInt("AGENT_FROM"));
    detail.setAgntTo(rs.getInt("AGENT_TO"));
    detail.setSttlVol(rs.getInt("SETTLE_VOLUME"));
    sttlAmt.setCcy(rs.getString("AMOUNT_CURRENCY"));
    sttlAmt.setValue(rs.getDouble("SETTLE_AMOUNT"));
    detail.setSttlAmt(sttlAmt);

    return detail;
}

}

我希望这可以帮助你。