mapper的兩種寫法
1.mapper接口+mapper.xml文件的方式(xml可以理解為實現(xiàn)類，由xml文件殃饿，mapper配置就寫xml文件；沒有xml文件就寫接口類)
mapper接口如下
package com.mapper;
import com.pojo.Teacher;
import java.util.List;
public interface TeacherMapper {
public List<Teacher> findAll();
}
mapper.xml如下
注意：namespace的值一般為接口所在的包名加接口名
"com.mapper.TeacherMapper"
<?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.mapper.TeacherMapper">
<resultMap id="teacherMap" type="Teacher">
<id property="id" column="id"/>
<result property="name" column="t_name"/>
</resultMap>
<select id="findAll" resultMap="teacherMap">
select * from tb_teacher
</select>
</mapper>
在整體的配置文件中，要寫xml的全名
<mapper resource="mapper/teacherMapper.xml"/>
若接口和xml文件在同一包下，并且名字相同辜限，則可以寫接口的全名**
<mapper class="com.mapper.TeacherMapper"/>
2.mapper接口加注解的方式
直接將mapper.xml配置文件用注解的方式寫在接口中，所以只有一個mapper的接口,其中result代表resultMap
mapper接口
package com.mapper;
import com.pojo.Teacher;
import org.apache.ibatis.annotations.Result;
import org.apache.ibatis.annotations.Results;
import org.apache.ibatis.annotations.Select;
import java.util.List;
public interface TeacherMapper {
@Select("select * from tb_teacher")
@Results({
@Result(property = "id",column = "id"),
@Result(property = "name",column = "t_name")
})
public List<Teacher> findAll();
}
在整體的配置文件中严蓖，要寫接口的全名
<mapper class="com.mapper.TeacherMapper"/>s
調(diào)用的兩種寫法
1.使用SqlSession的selectOne薄嫡，selectList，selectMap方法
package com.dao;
import com.pojo.Teacher;
import com.util.MyBatisUtil;
import org.apache.ibatis.session.SqlSession;
import java.util.List;
public class UserDao {
private SqlSession sqlSession = MyBatisUtil.getSqlSession();
public List<Teacher> findAll(){
List<Teacher> list = sqlSession.selectList("com.mapper.TeacherMapper.findAll");
return list;
}
}
2.調(diào)用mapper接口的方法
package com.dao;
import com.mapper.TeacherMapper;
import com.pojo.Teacher;
import com.util.MyBatisUtil;
import org.apache.ibatis.session.SqlSession;
import java.util.List;
public class TeacherDao {
private SqlSession sqlSession = MyBatisUtil.getSqlSession();
public List<Teacher> findAll(){
TeacherMapper mapper = sqlSession.getMapper(TeacherMapper.class);
List<Teacher> list = mapper.findAll();
return list;
}
}
