mybatis中xml文件的核心

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<?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.bootdo.common.dao.DictDao">

<select id="get" resultType="com.bootdo.common.domain.DictDO">

select

`id`,`name`,`value`,`type`,`description`,`sort`,`parent_id`,`create_by`,`create_date`,`update_by`,`update_date`,`remarks`,`del_flag`

from sys_dict where id = #{value}

</select>

<select id="list" resultType="com.bootdo.common.domain.DictDO">

select

`id`,`name`,`value`,`type`,`description`,`sort`,`parent_id`,`create_by`,`create_date`,`update_by`,`update_date`,`remarks`,`del_flag`

from sys_dict

<where>

<if test="id != null and id != ''"> and id = #{id} </if>

<if test="name != null and name != ''"> and name = #{name} </if>

<if test="value != null and value != ''"> and value = #{value} </if>

<if test="type != null and type != ''"> and type = #{type} </if>

<if test="description != null and description != ''"> and description = #{description} </if>

<if test="sort != null and sort != ''"> and sort = #{sort} </if>

<if test="parentId != null and parentId != ''"> and parent_id = #{parentId} </if>

<if test="createBy != null and createBy != ''"> and create_by = #{createBy} </if>

<if test="createDate != null and createDate != ''"> and create_date = #{createDate} </if>

<if test="updateBy != null and updateBy != ''"> and update_by = #{updateBy} </if>

<if test="updateDate != null and updateDate != ''"> and update_date = #{updateDate} </if>

<if test="remarks != null and remarks != ''"> and remarks = #{remarks} </if>

<if test="delFlag != null and delFlag != ''"> and del_flag = #{delFlag} </if>

</where>

<choose>

<when test="sort != null and sort.trim() != ''">

order by ${sort} ${order}

</when>

<otherwise>

order by id desc

</otherwise>

</choose>

<if test="offset != null and limit != null">

limit #{offset}, #{limit}

</if>

</select>

<select id="count" resultType="int">

select count(*) from sys_dict

<where>

<if test="id != null and id != ''"> and id = #{id} </if>

<if test="name != null and name != ''"> and name = #{name} </if>

<if test="value != null and value != ''"> and value = #{value} </if>

<if test="type != null and type != ''"> and type = #{type} </if>

<if test="description != null and description != ''"> and description = #{description} </if>

<if test="sort != null and sort != ''"> and sort = #{sort} </if>

<if test="parentId != null and parentId != ''"> and parent_id = #{parentId} </if>

<if test="createBy != null and createBy != ''"> and create_by = #{createBy} </if>

<if test="createDate != null and createDate != ''"> and create_date = #{createDate} </if>

<if test="updateBy != null and updateBy != ''"> and update_by = #{updateBy} </if>

<if test="updateDate != null and updateDate != ''"> and update_date = #{updateDate} </if>

<if test="remarks != null and remarks != ''"> and remarks = #{remarks} </if>

<if test="delFlag != null and delFlag != ''"> and del_flag = #{delFlag} </if>

</where>

</select>

<insert id="save" parameterType="com.bootdo.common.domain.DictDO"

useGeneratedKeys="true" keyProperty="id">

insert into sys_dict

(

`name`,

`value`,

`type`,

`description`,

`sort`,

`parent_id`,

`create_by`,

`create_date`,

`update_by`,

`update_date`,

`remarks`,

`del_flag`

)

values

(

#{name},

#{value},

#{type},

#{description},

#{sort},

#{parentId},

#{createBy},

#{createDate},

#{updateBy},

#{updateDate},

#{remarks},

#{delFlag}

)

</insert>

<update id="update" parameterType="com.bootdo.common.domain.DictDO">

update sys_dict

<set>

<if test="name != null">`name` = #{name}, </if>

<if test="value != null">`value` = #{value}, </if>

<if test="type != null">`type` = #{type}, </if>

<if test="description != null">`description` = #{description}, </if>

<if test="sort != null">`sort` = #{sort}, </if>

<if test="parentId != null">`parent_id` = #{parentId}, </if>

<if test="createBy != null">`create_by` = #{createBy}, </if>

<if test="createDate != null">`create_date` = #{createDate}, </if>

<if test="updateBy != null">`update_by` = #{updateBy}, </if>

<if test="updateDate != null">`update_date` = #{updateDate}, </if>

<if test="remarks != null">`remarks` = #{remarks}, </if>

<if test="delFlag != null">`del_flag` = #{delFlag}</if>

</set>

where id = #{id}

</update>

<delete id="remove">

delete from sys_dict where id = #{value}

</delete>

<delete id="batchRemove">

delete from sys_dict where id in

<foreach item="id" collection="array" open="(" separator=","

close=")">

#{id}

</foreach>

</delete>

<select id="listType" resultType="com.bootdo.common.domain.DictDO">

select distinct `type` , description from sys_dict

</select>

</mapper>

在我的理解中：xml文件时真正操作数据库的。

在xml文件中，和xml文件相关联的文件有两个：

一个是dao层的dao文件：这个文件是受到service所控制的

二一个是damain层中的实体类，这个是供返回的数据类型所使用。

正好，如果XML文件操作 的是实体类的话，并且用这个实体类在数据库中创建表，那么增删改查中的字段正好是这个实体类中的字段。不过也没关系。xml层操作的数据库中的表可以不写在xml文件中作为导入引入来处理。

注意是一个xml文件对应一个dao层文件。

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