Mybaits学习 - 2 - 用接口实现查询

创建接口类

package dao;

import bean.Teacher;

public interface TeacherMapper {

    public Teacher getTeacherByID(Integer id);
}

修改mapper文件为

<?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指定为接口的全类名 -->
<mapper namespace="dao.TeacherMapper">
    <!--id：自定义的sql唯一标志:使用接口的方法名-->
    <select id="getTeacherByID" resultType="bean.Teacher">
    select * from teacher where id = #{id}
  </select>
</mapper>

测试代码

    @Test
    public void testCase2() throws IOException {
        String resource = "mybatis-config.xml";
        InputStream inputStream = Resources.getResourceAsStream(resource);


        //创建sqlSessionFactory对象
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);

        //生成session实例
        SqlSession session = sqlSessionFactory.openSession();

        try{
        //获取接口的实现
        //TeacherMapper teacherMapper = session.getMapper(TeacherMapper.class);
            TeacherMapper teacherMapper = session.getMapper(TeacherMapper.class);
            Teacher teacher = teacherMapper.getTeacherByID(1);
            System.out.println(teacher);}
        finally {
            session.close();
        }

    }

执行结果：