MyBatis的核心配置文件以及映射文件

<?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>
    <!-- 配置环境 -->
    <environments default="mysql">
        <environment id="mysql">
            <!-- 事务类型 -->
            <transactionManager type="JDBC"></transactionManager>
            <!-- 数据源 -->
            <dataSource type="POOLED">
                <property name="driver" value="com.mysql.cj.jdbc.Driver"/>
                <property name="url" value="jdbc:mysql:///mybatis"/>
                <property name="username" value="root"/>
                <property name="password" value="666666"/>
            </dataSource>
        </environment>
    </environments>
</configuration>

<?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.mybatisstudy.mapper.UserMapper">
</mapper>

<select id="findById" parameterType="int" resultType="com.mybatisstudy.pojo.User">
    select * from user where id = #{id}
</select>

<!-- 注册映射文件 -->
    <mappers>
        <mapper resource="com/mybatisstudy/mapper/UserMapper.xml"></mapper>
    </mappers>