~~~ <?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.sn.demo1.dao.UserMapper"> <select id="findUserById" parameterType="int" resultType="com.sn.demo1.User"> select * from pt_user where id = #{id} </select> </mapper> ~~~