配置文件

${dirver} ---> com.mysql.jdbc.Driver

${url} ---> jdbc:mysql://localhost:3306/数据库名

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE configurationPUBLIC "-//mybatis.org//DTD Config 3.0//EN""https://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration><environments default="development">
<!--配置数据源，即数据库信息--><environment id="development"><transactionManager type="JDBC"/><dataSource type="POOLED"><property name="driver" value="${driver}"/><property name="url" value="${url}"/><property name="username" value="${username}"/><property name="password" value="${password}"/></dataSource></environment></environments>
<!--引入映射文件,路径：src/main/resources/mapper/BlogMapper.xml--><mappers><mapper resource="mapper/BlogMapper.xml"/></mappers>
</configuration>

Mapper映射文件

mybatis面向接口编程，需要保持两个一致性：

(1)映射文件中的namespace(命名空间)和Mapper接口的全类名保持一致；

(2)映射文件中sql语句中的id需要和Mapper接口的方法名保持一致；

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapperPUBLIC "-//mybatis.org//DTD Mapper 3.0//EN""https://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="org.mybatis.example.BlogMapper"><select id="selectBlog" resultType="Blog">select * from Blog where id = #{id}</select>
</mapper>