基于Oracle Sequence的流水号生成规则

流水号在各种系统中随处可见，一般都是使用自增、年月日时分秒+自增、UUID等，要么纯数字，要么纯字母，这种流水号缺乏一定的辨识度。

下面为大家介绍一种具有辨识度的流水号的生成方式：领域或者应用的标识 + 表名的英文缩写(单词的第一个字母) + 年月日(或者年月日时分秒) + Oracle Sequence自增。

代码示例：

package com.pab.bloan.order.service;

/**
 * Created by 
 */
public interface SequenceGeneratorService {
    /**
     * 根据SequenceName获取流水号
     * @param prefix
     * @param seqName
     * @return
     */
    String getSerialNo(String prefix, String seqName);

    /**
     * 根据指定的流水号的前缀、长度、SequenceName获取流水号
     * @param prefix
     * @param idLength
     * @param seqName
     * @return
     */
    String getSerialNo(String prefix, Integer idLength, String seqName);
}

package com.pab.bloan.order.service.impl;

import java.util.Date;
import lombok.extern.slf4j.Slf4j;
import com.pab.bloan.order.utils.DateUtils;
import org.apache.commons.lang3.StringUtils;
import org.springframework.stereotype.Service;
import com.pab.bloan.order.dao.bloanb.SequencePojoMapper;
import com.pab.bloan.order.service.SequenceGeneratorService;
import org.springframework.beans.factory.annotation.Autowired;

/**
 * 获取流水号服务
 * Created by 
 */
@Slf4j
@Service
public class SequenceGeneratorServiceImpl implements SequenceGeneratorService {
    @Autowired
    private SequencePojoMapper sequencePojoMapper;

    /**
     * {@inheritDoc}
     * @param seqName
     * @return
     */
    @Override
    public String getSerialNo(String prefix, String seqName) {
        return getSerialNo(prefix, 0, seqName);
    }

    /**
     * {@inheritDoc}
     * @param prefix
     * @param idLength
     * @param seqName
     * @return
     */
    @Override
    public String getSerialNo(String prefix, Integer idLength, String seqName) {
        try {
            if (StringUtils.isEmpty(seqName)) {
                return "";
            }
            if (idLength < 8){
                idLength = 8;
            } else if (idLength > 12){
                idLength = 12;
            }
            
            String dateString = DateUtils.formatDate(new Date(),"yyyy/MM/dd");
            dateString = dateString.replace("/", "");

            StringBuilder sequenceSqlBuilder = new StringBuilder();
            sequenceSqlBuilder.append(" select ");
            sequenceSqlBuilder.append(seqName + ".NEXTVAL");
            sequenceSqlBuilder.append(" FROM DUAL ");

            Long sequenceId = sequencePojoMapper.getSequenceBySequenceName(sequenceSqlBuilder.toString());
            String seqIdString = String.format("%0" + idLength + "d", sequenceId);

            String serialNo;
            if (seqIdString.length() > idLength) {
                serialNo = String.format("%s%s%s", prefix, dateString, seqIdString.substring(seqIdString.length() - idLength, seqIdString.length()));
            } else {
                serialNo = String.format("%s%s%s", prefix, dateString, seqIdString);
            }
            return serialNo;
        } catch (Exception e) {
            log.error("SequenceGeneratorService.getSerialNo", e);
        }
        return "";
    }
}

Mybatis Mapper.xml文件(不能使用缓存，因为在打开缓存的情况下，连续获取Sequence，会得到重复的值)

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.pab.bloan.order.dao.bloanb.SequencePojoMapper">

    <select id="getSequenceBySequenceName" resultType="java.lang.Long"
            useCache="false" flushCache="true">
        ${sql}
    </select>
</mapper>

让自己业务中流水号具有辨识度，在关联查询时，一眼便可以看出数据源自何处。