mybatis的mapper代理

UserMapper(Interface)

package com.iot.mybatis.mapper;

import com.iot.mybatis.po.User;

//接口中的方法名,输入参数的类型,返回值类型和mapper.xml中的statement的id一致,
public interface UserMapper {
    public User findUserById(int id) throws Exception;
}

UserMapper.xml

<?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.xml中，命名空间的地址就是mapper接口的地址-->
<mapper namespace="com.iot.mybatis.mapper.UserMapper">

    <select id="findUserById" parameterType="int" resultType="com.iot.mybatis.po.User">
        select * from user where id=#{value}
    </select>

    <select id="findUserByName" parameterType="String" resultType="com.iot.mybatis.po.User">
        select * from user where username like '%${value}%'
    </select>

    <insert id="insertUser" parameterType="com.iot.mybatis.po.User">
        <selectKey keyProperty="id" order="AFTER" resultType="java.lang.Integer">
            SELECT LAST_INSERT_ID()
        </selectKey>
        insert into user (username,birthday,sex,address) value (#{username},#{birthday},#{sex},#{address})
    </insert>

    <delete id="deleteUser" parameterType="java.lang.Integer">
        delete from user where id=#{value}
    </delete>
    
    <update id="updateUser" parameterType="com.iot.mybatis.po.User">
        update user set username=#{username},birthday=#{birthday},sex=#{sex},address=#{address} where id=#{id}
    </update>
</mapper>

sqlMapConfig.xml

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE configuration
        PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>
    <!--数据库环境-->
    <environments default="development">
        <environment id="development">
            <transactionManager type="JDBC"/>
            <dataSource type="POOLED">
                <property name="driver" value="com.mysql.jdbc.Driver"/>
                <property name="url" value="jdbc:mysql://localhost:3306/mydb1?characterEncoding=utf-8"/>
                <property name="username" value="root"/>
                <property name="password" value="123456"/>
            </dataSource>
        </environment>
    </environments>
    <!--用于配置映射器-->
    <mappers>
        <mapper resource="mapper/UserMapper.xml"/>
    </mappers>