mybatis中parameterType和resuktType的使用方法

<?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="july.wild.dao.IUserDao">
    <!--id属性为parameterType的名称随便起， type为全限定类名-->

    <resultMap id="userResultMap" type="july.wild.domain.Users">
        <!--首先配置主键id property是属性名 column是对应的数据库列名-->
        <id property="Sno" column="sno"/>
        <result property="username" column="sname"></result>
        <result property="userage" column="sage"></result>
        <result property="userscore" column="score"></result>
        <result property="usersex" column="ssex"></result>

    </resultMap>
    
    <!--parameter的配置  id属性为parameterType的名称随便起， type为全限定类名-->
    <parameterMap id="userMap" type="july.wild.domain.Users">
        <parameter property="Sno" resultMap="ueerResultMap"></parameter>
        <parameter property="username" resultMap="userResultMap"></parameter>
        <parameter property="userage" resultMap="userResultMap"></parameter>
        <parameter property="userscore" resultMap="userResultMap"></parameter>
        <parameter property="usersex" resultMap="userResultMap"></parameter>
    </parameterMap>

    <!--配置查询所有-->
    <select id="FindAll" resultType="july.wild.domain.Users">
        select * from stu;
    </select>

    <insert id="insert" parameterMap="userMap">
<selectKey order="AFTER" >
    select last_insert_id()
</selectKey>
insert into stu(sno,sname,sage,score,ssex) values(#{Sno},#{username},#{userage},#{userscore},#{usersex})

    </insert>



    <select id="findOne" resultType="users"  >
        select * from stu where 1 = 1
        <if test="_parameter != null">
         and   sname = #{sname}
        </if>

        <if test="_parameter != null">
            and ssex = #{ssex}
        </if>
    </select>


</mapper>