关于mybatis:练习mybatis多对一关系

对于老师而言，汇合，一个老师有很多学生【一对多】

SQL：

CREATE TABLE `teacher` (`id` INT(10) NOT NULL,`name` VARCHAR(30) DEFAULT NULL,PRIMARY KEY (`id`)) ENGINE=INNODB DEFAULT CHARSET=utf8INSERT INTO teacher(`id`, `name`) VALUES (1, 计算机老师); CREATE TABLE `student` (`id` INT(10) NOT NULL,`name` VARCHAR(30) DEFAULT NULL,`tid` INT(10) DEFAULT NULL,PRIMARY KEY (`id`),KEY `fktid` (`tid`),CONSTRAINT `fktid` FOREIGN KEY (`tid`) REFERENCES `teacher` (`id`)) ENGINE=INNODB DEFAULT CHARSET=utf8INSERT INTO `student` (`id`, `name`, `tid`) VALUES (1, 小明, 1); INSERT INTO `student` (`id`, `name`, `tid`) VALUES (2, 小红, 1); INSERT INTO `student` (`id`, `name`, `tid`) VALUES (3, 小张, 1); INSERT INTO `student` (`id`, `name`, `tid`) VALUES (4, 小李, 1); INSERT INTO `student` (`id`, `name`, `tid`) VALUES (5, 小王, 1);

测试环境搭建
1.导入lombok
2.新建实体类Teacher，Student

@Datapublic class Student{  private int id;  private String name;  //学生须要关联一个老师！  private Teacher teacher;}

@Datapublic class Teacher{  private int id;  private String name;}

3.建设Dao接口TeacherDao，StudentDao

public interface TeacherDao{  @Select("select * from teacher where id=#{tid}")  Teacher getTeacher(@Param("tid") int id);}

public interface StudentDao{}

4.建设Mapper.xml文件
在resources目录创立com.jialidun.dao包

<!DOCTYPE mapper  PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"  "http://mybatis.org/dtd/mybatis-3-mapper.dtd"><mapper namespace="com.jialidun.dao.TeacherDao">  </mapper>

<!DOCTYPE mapper  PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"  "http://mybatis.org/dtd/mybatis-3-mapper.dtd"><mapper namespace="com.jialidun.dao.StudentDao">  </mapper>

5.在外围配置文件中绑定注册咱们的Mapper接口或者文件！

<mappers>  <mapper resource="com/jialidun/dao/*.xml"/>  <mapper class="com.jialidun.dao.*"/></mappers>

6.测试查问胜利

public class TestDemo{  @Test  public void test01(){      SqlSession sqlSession = MybatisUtils.getSqlSession();      TeacherDap mapper = sqlSession.getBean(TeacherDao.class);      Teacher teacher = mapper.getTeacher(1);      System.out.println(teacher);      sqlSession.close();  }}