In的写法

<select id="hejiByHeadIds" parameterType="Map" resultMap="ExchangeBillResult">
   SELECT  IFNULL(SUM(cash), 0)cash , IFNULL(SUM(oilTicket),0)oilTicket , IFNULL(SUM(unionpay),0)unionpay , IFNULL(SUM(youhui),0)youhui  
   from t_jyz_z_exchange_bill 
   <where>
      <if test="baoBiaoHead_ids!=null ">
         and  headId  in 
          <foreach item="i" collection="baoBiaoHead_ids" open="(" separator="," close=")" >
            #{i}
         </foreach>
      </if>
   </where>
</select>




如果参数不是map  是直接一个list可以按下这个写。
<select id="getHeji" parameterType="java.util.List" resultType="java.lang.Integer">
    SELECT SUM(month_value) FROM t_record_value
    <where>
        <if test="arg0 != null and arg0.size() > 0">
            AND record_head_id IN
            <foreach item="item" collection="arg0" open="(" separator="," close=")">
                #{item}
            </foreach>
        </if>
    </where>
</select>