MyBaits —— 通过调用接口映射sql语句

public interface EmployeeMapper {
    public Employee getEmpById(Integer id);
}

<?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">
<!--namespace：名称空间，对应mapper接口的全类名-->
<mapper namespace="com.sangyu.mapper.EmployeeMapper">
    <!--
    id:唯一标识
    resultType:返回值类型，对应的Bean类型
    {#id}：从传递过来的参数中取出id值
    select 中增加别名，防止因为mysql中的字段与bean中的不对应，导致该字段查询出来的结果为空
    -->
    <select id="getEmpId" resultType="com.sangyu.bean.Employee">
    select id,last_name lastName,email,gender from tbl_employee where id = #{id}
  </select>
</mapper>

public class MyBatisTest {

    @Test
    public void Test() throws IOException {
        String resource = "mybatis-config.xml";
        InputStream inputStream = Resources.getResourceAsStream(resource);
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream); // 根据xml创建sqlSessionFactory
        SqlSession session = sqlSessionFactory.openSession(); // 2. 从 SqlSessionFactory 中获取 SqlSession 的实例，SqlSession 提供了在数据库执行 SQL 命令所需的所有方法。你可以通过 SqlSession 实例来直接执行已映射的 SQL 语句
        try {
            // 3. 获取接口的实现类对象
            EmployeeMapper mapper = session.getMapper(EmployeeMapper.class);
            Employee employee = mapper.getEmpById(1);
            System.out.println(employee);
        }finally {
            session.close();
        }
    }
}