处理大于小于号的方法：
https://www.cnblogs.com/winner-0715/p/6132755.html
第一种方法：
用转义字符把">"和"<"替换掉，就没有问题了。
<if test="startTime != null ">
AND order_date >= #{startTime,jdbcType=DATE}
</if>
<if test="endTime != null ">
AND order_date <= #{endTime,jdbcType=DATE}
</if>
注意下，这里的startTime，endTime都是Date类型的~
附：XML转义字符
| < | < | 小于号 |
| > | > | 大于号 |
| & | & | 和 |
| ' | ’ | 单引号 |
| " | " | 双引号 |
第二种方法：
因为这个是xml格式的，所以不允许出现类似">"这样的字符，但是可以使用<![CDATA[ ]]>符号进行说明，将此类符号不进行解析
mapper文件示例代码
<if test="startTime != null ">
AND <![CDATA[ order_date >= #{startTime,jdbcType=DATE} ]]>
</if>
<if test="endTime != null ">
AND <![CDATA[ order_date <= #{endTime,jdbcType=DATE} ]]>
</if>
====================================
附带问题：
使用情况：mybatis xml中写的mapper 对接的是postgresql数据库
问题：在同一个项目中不同的mapper.xml文件中，分别出现了>= 和<=的比较运算符，但是在一个xml中需要额外处理才能使用，一个xml文件中不需要额外处理>或者<符号可以直接使用
下面附上两个xml文件代码和截图，
1.
<?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.rollong.chinatower.server.persistence.mapper.FinanceReportMapper">
<resultMap id="financeBriefDataResultMap"
type="com.rollong.chinatower.server.api.payload.finance.FinanceBriefData">
<id property="id" column="id"/>
</resultMap>
<select id="search" resultMap="financeBriefDataResultMap">
SELECT
*
FROM
(
SELECT
( CAST ( partner.id AS VARCHAR ) || '@partner' ) AS ID,
partner.id AS partnerId,
project.id AS projectId,
construction.id AS constructionId,
NULL AS takerId,
NULL AS maintenanceId,
count(report.id) as reportsCount,
sum(report.amount) as totalAmount,
max(report.updated_at) as reportLatestUpdatedAt
FROM
"project"."project_construction_partners" AS partner
LEFT JOIN "project"."project_construction" AS construction ON partner.construction_id = construction.id
LEFT JOIN "project"."projects" AS project ON construction.project_id = project.id
LEFT JOIN "finance"."finance_reports" as report on partner.id = report.partner_id
WHERE
#{isConstruction} = TRUE
AND construction.deleted_at IS NULL
<if test="null != partnerType">
AND partner.name = '${partnerType}'
</if>
<if test="null != provinceId">
AND project.province_id = #{provinceId}
</if>
<if test="null != cityId">
AND project.city_id = #{cityId}
</if>
<if test="null != districtId">
AND project.district_id = #{districtId}
</if>
<if test="null != subCompanyId">
AND project.sub_company_id = #{subCompanyId}
</if>
<if test="null != thirdPartCompanyId">
AND partner.third_part_id = #{thirdPartCompanyId}
</if>
<if test="null != leaderEmployeeId">
AND partner.leader_employee_id = #{leaderEmployeeId}
</if>
<if test="null != workerEmployeeId">
AND exists(
select 1 from "third_part"."worker_involved_constructions" as involved
where involved.worker_id = #{workerEmployeeId} AND involved.project_partner_id = partner.id
)
</if>
<if test="null != reportStatus">
AND exists(
select 1 from "finance"."finance_reports" as r
where r.partner_id = partner.id
<choose>
<when test="'Submit' == reportStatus">
and r.approved_at is null and r.rejected_at is null and r.paid_at is null
</when>
<when test="'Approved' == reportStatus">
and r.approved_at is not null and r.rejected_at is null and r.paid_at is null
</when>
<when test="'Rejected' == reportStatus">
and r.approved_at is null and r.rejected_at is not null and r.paid_at is null
</when>
<when test="'Paid' == reportStatus">
and r.paid_at is not null
</when>
</choose>
)
</if>
<if test="null != keyword">
AND project.name like #{keyword}
</if>
GROUP BY partner.id,project.id,construction.id
UNION
SELECT
( CAST ( taker.ID AS VARCHAR ) || '@maintenance' ) AS ID,
NULL AS partnerId,
project.ID AS projectId,
NULL AS constructionId,
taker.ID AS takerId,
maintenance.ID AS maintenanceId,
count(report.id) as reportsCount,
sum(report.amount) as totalAmount,
max(report.updated_at) as reportLatestUpdatedAt
FROM
"project"."project_maintenance_takers" AS taker
LEFT JOIN "project"."project_maintenance" AS maintenance ON taker.maintenance_id = maintenance.id
LEFT JOIN "project"."projects" AS project ON maintenance.project_id = project.id
LEFT JOIN "finance"."finance_reports" as report on taker.id = report.taker_id
WHERE
#{isMaintenance} = TRUE
AND maintenance.deleted_at IS NULL
AND taker.deleted_at IS NULL
<if test="null != provinceId">
AND project.province_id = #{provinceId}
</if>
<if test="null != cityId">
AND project.city_id = #{cityId}
</if>
<if test="null != districtId">
AND project.district_id = #{districtId}
</if>
<if test="null != subCompanyId">
AND project.sub_company_id = #{subCompanyId}
</if>
<if test="null != thirdPartCompanyId">
AND taker.third_part_id = #{thirdPartCompanyId}
</if>
<if test="null != leaderEmployeeId">
AND taker.leader_employee_id = #{leaderEmployeeId}
</if>
<if test="null != workerEmployeeId">
AND exists(
select 1 from "third_part"."worker_involved_maintenance" as involved
where involved.worker_id = #{workerEmployeeId} AND involved.taker_id = taker.id
)
</if>
<if test="null != reportStatus">
AND exists(
select 1 from "finance"."finance_reports" as r
where r.taker_id = taker.id
<choose>
<when test="'Submit' == reportStatus">
and r.approved_at is null and r.rejected_at is null and r.paid_at is null
</when>
<when test="'Approved' == reportStatus">
and r.approved_at is not null and r.rejected_at is null and r.paid_at is null
</when>
<when test="'Rejected' == reportStatus">
and r.approved_at is null and r.rejected_at is not null and r.paid_at is null
</when>
<when test="'Paid' == reportStatus">
and r.paid_at is not null
</when>
</choose>
)
</if>
<if test="null != keyword">
AND project.name like #{keyword}
</if>
GROUP BY maintenance.id,project.id,taker.id
) AS table_all
WHERE TRUE
<if test="minReportsCount != null">
AND table_all.reportsCount >= #{minReportsCount}
</if>
<if test="maxReportsCount != null">
AND table_all.reportsCount <= #{maxReportsCount}
</if>
<choose>
<when test="sort == 'Latest'">
ORDER BY table_all.reportLatestUpdatedAt DESC
</when>
<when test="sort == 'AmountAsc'">
ORDER BY table_all.totalAmount ASC
</when>
<when test="sort == 'AmountDesc'">
ORDER BY table_all.totalAmount DESC
</when>
</choose>
</select>
</mapper>
2.
<?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.rollong.chinatower.server.persistence.mapper.OrderMealTimeMapper">
<resultMap id="OrderMealResult"
type="com.rollong.chinatower.server.api.payload.canteen.OrderMealTime" autoMapping="true">
<result property="years" column="years"/>
<result property="months" column="months"/>
<result property="days" column="days"/>
<result property="counts" column="counts"/>
<result property="checkOut" column="checkOut"/>
</resultMap>
<select id="search" resultMap="OrderMealResult">
SELECT
ors.year_meal AS years,
ors.month_meal AS months,
ors.day_meal AS days,
SUM (ors.counts) AS counts,
SUM (ors.checkd_out) AS checkOut
FROM canteen.order_meal ors
WHERE TRUE
<if test="null != canteenId">
AND ors.canteen_id = #{canteenId}
</if>
<if test=" null != startY and null != startM and null != startD" >
AND <![CDATA[ (ors.year_meal *10000 + ors.month_meal *100 + ors.day_meal) >= (#{startY}*10000+#{startM}*100+#{startD}) ]]>
</if>
<if test=" null != endY and null != endM and null != endD" >
AND <![CDATA[ (ors.year_meal *10000 + ors.month_meal *100 + ors.day_meal) <= (#{endY}*10000+#{endM}*100+#{endD}) ]]>
</if>
GROUP BY ors.year_meal,ors.month_meal,ors.day_meal
</select>
</mapper>
【究竟是xml的问题/还是对接的数据库的问题/还是数据库中对于某些类型字段处理不一样】
如果有兴趣或者刚好知道，遇到过这种情况的 希望大家能给个反馈，多多交流！！