mybatis 总结

前面写的关于 mybatis 的，进行总结的文章

include

主要针对 mybatis 中 sql 语句的复用，可以减少代码量，例如下：

<sql id="insertIntoHoldSql">INSERT INTO tb_day_hold (…… )VALUES (……)</sql><insert id="addOrUpdateOne_addAmount" parameterType="……Domain"><include refid="insertIntoHoldSql"></include><![CDATA[ON DUPLICATE KEY UPDATEamount = amount + VALUES(amount);]]></insert>

组合之后，addOrUpdateOne_addAmount 的 sql 语句，就是 insert into …… ON DUPLICATE KEY UPDATE ……两者拼组之后的 SQL 语句

choose

没见着 mybatis 中，有 if else 的使用，而 choose when 可以替代这个功能，如下：

<choose><when test="…… ">……</when><when test="…… ">……</when><otherwise>……</otherwise></choose>

if

if 多用于查询条件的拼组，如下：

    WHERE ……    <if test="……">          ……    </if>   <if test="…… ">          ……    </if>   

foreach

foreach 一般循环 mybatis 中传递过来的 list ，进行逐条操作，如下：

<foreach collection="list" index="index" item="item">……#{item.firm_account  } ,……;</foreach>

实例

以下是我们项目，真实使用的代码的实例，已经过测试，如下：

<?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.hundsun.cloudtrade.match.dao.IDayHoldDao"><sql id="insertIntoHoldSql">INSERT INTO tb_day_hold (firm_account    ,seat_no         ,stock_account   ,exchange_type   ,stock_name      ,stock_code      ,amount          ,market_value    ,position_str    )VALUES (#{firm_account  } ,#{seat_no       } ,#{stock_account } ,#{exchange_type } ,#{stock_name    } ,#{stock_code    } ,<choose><when test="occur_amount != null and occur_amount != '' ">#{occur_amount        } ,  </when><when test="amount != null and amount != '' ">#{amount        } ,  </when><otherwise>0,</otherwise></choose>#{market_value  } ,#{position_str  } )</sql><insert id="addOrUpdateOne_addAmount" parameterType="com.hundsun.cloudtrade.match.domain.DayHoldDomain"><include refid="insertIntoHoldSql"></include><![CDATA[ON DUPLICATE KEY UPDATEamount = amount + VALUES(amount);]]></insert><insert id="addOrUpdateOne_amount" parameterType="com.hundsun.cloudtrade.match.domain.DayHoldDomain"><include refid="insertIntoHoldSql"></include><![CDATA[ON DUPLICATE KEY UPDATEamount = VALUES(amount) , seat_no = VALUES(seat_no);]]></insert><insert id="batchInsert" parameterType="java.util.List"><foreach collection="list" index="index" item="item">INSERT INTO tb_day_hold (firm_account    ,seat_no         ,stock_account   ,exchange_type   ,stock_name      ,stock_code      ,amount          ,market_value    ,position_str    )VALUES (#{item.firm_account  } ,#{item.seat_no       } ,#{item.stock_account } ,#{item.exchange_type } ,#{item.stock_name    } ,#{item.stock_code    } ,#{item.amount        } ,  #{item.market_value  } ,#{item.position_str  } )ON DUPLICATE KEY UPDATEamount = VALUES(amount) , seat_no = VALUES(seat_no);</foreach></insert><select id="qryMultiRecords"parameterType="com.hundsun.cloudtrade.match.dto.req.QryHoldReq"resultType="com.hundsun.cloudtrade.match.domain.DayHoldDomain">SELECT     firm_account    ,seat_no         ,stock_account   ,exchange_type   ,stock_name      ,stock_code      ,amount          ,market_value    ,position_str    <choose><!-- 查询历史持仓表 -->    <when test="hold_date != null and hold_date != '' ">    ,hold_date FROM tb_history_hold    </when>    <!-- 查询当日持仓 -->    <otherwise>    ,'' hold_date FROM tb_day_hold    </otherwise>    </choose>    WHERE firm_account = #{firm_account}    <if test="seat_no != null and seat_no != '' ">          AND seat_no = #{seat_no}      </if>   <if test="exchange_type != null and exchange_type != '' ">          AND exchange_type = #{exchange_type}      </if>   <if test="stock_account != null and stock_account != '' ">          AND stock_account = #{stock_account}      </if>   <if test="position_str != null and position_str != '' ">          AND position_str = #{position_str}      </if>       ORDER BY stock_code DESC<if test="req_number != null and req_number != '' ">          LIMIT 0,#{req_number}    </if>    ;</select><delete id="delMultiRecords" parameterType="com.hundsun.cloudtrade.match.dto.req.DelHoldsReq"><![CDATA[DELETE FROM tb_history_hold WHERE firm_account = #{firm_account};DELETE FROM tb_day_hold WHERE firm_account = #{firm_account};]]></delete></mapper>

以上