Question

为什么会报错，sql语句在mapper.xml里的写法有什么不同吗？

Answer 1

mybatis的sqlmap是xml格式的文件，你的代码里出现了小于号，而小于号是xml的组成部分，要用CDATA包裹住才不报错。
示例代码：
<select id="selectMonth" parameterType="java.util.HashMap" resultType="com.bilysice.chemicalPark.entity.ReFactor">
select
rf.item_id as itemId
, rf.device_id as deviceId
, rf.station_id as stationId
, rf.seq_date as seqDate
, rf.average_value averageValue
from re_factor rf
<where>
<if test=" itemId !=null">and rf.item_id = #{itemId}</if>
<if test=" deviceId !=null">and rf.device_id = #{deviceId}</if>
<if test=" station_id !=null">
and rf.station_id in
<foreach item="s" collection="stationIds" index="index" open="(" separator="," close=")">
#{s}
</foreach>
</if>
<if test=" stationId !=null">and rf.station_id = #{stationId}</if>
<if test=" srhTimeBegin !=null">and rf.seq_date <![CDATA[>=]]> #{srhTimeBegin}</if>
<if test=" srhTimeEnd !=null">and rf.seq_date <![CDATA[<]]> #{srhTimeEnd}</if>
</where>
</select>