标签：name 查询 tid org MyBatis import com id 搭建
复杂查询环境搭建
多个学生对应一个老师
对于学生而言，关联多个学生，关联一个老师
对于老师而已言，一个老师有多个学生（集合）
关联和集合
SQL
CREATE TABLE `teacher` (
`id` INT(10) NOT NULL,
`name` VARCHAR(30) DEFAULT NULL,
PRIMARY KEY (`id`)
) ;
INSERT INTO teacher(`id`, `name`) VALUES (1, '秦老师');
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`)
);
INSERT 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');
文件配置
两个实体类接口
package com.my.dao;
import com.my.pojo.Teacher;
import org.apache.ibatis.annotations.Param;
import org.apache.ibatis.annotations.Select;
public interface TeacherMapper {
@Select("select * from teacher where id = #{tid}")
Teacher getTeacher(@Param("tid") int id);
}
package com.my.dao;
public interface StudentMapper {
}
实体类
package com.my.pojo;
import lombok.Data;
@Data
public class Student {
private int id;
private String name;
//学生关联老师
private Teacher teacher;
}
package com.my.pojo;
import lombok.Data;
@Data
public class Teacher {
private int id;
private String name;
}
连接SqlSession
package com.my.utils;
import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;
import java.io.IOException;
import java.io.InputStream;
//sqlSessionFactory 构建sqlSession
public class MybatisUtils {
private static SqlSessionFactory sqlSessionFactory;
static {
try{
//使用mybatis第一步 获取sqlSessionFactory对象
String resource = "mybatis-config.xml";
InputStream inputStream = Resources.getResourceAsStream(resource);
sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
} catch (IOException e) {
e.printStackTrace();
}
}
public static SqlSession getSqlSession(){
return sqlSessionFactory.openSession(true);
}
}
资源文件
<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper
PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<!--核心配置文件-->
<mapper namespace="com.my.dao.StudentMapper">
</mapper>
<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper
PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<!--核心配置文件-->
<mapper namespace="com.my.dao.TeacherMapper">
</mapper>
<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE configuration
PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-config.dtd">
<!--核心配置文件-->
<configuration>
<!-- 引入外部配置文件-->
<properties resource="pp.properties"/>
<settings>
<!-- 标准的日志工厂-->
<setting name="logImpl" value="STDOUT_LOGGING"/>
<!-- <setting name="logImpl" value="LOG4J"/>-->
</settings>
<!--给实体类起别名-->
<typeAliases>
<package name="com.my.pojo"/>
</typeAliases>
<environments default="development">
<environment id="development">
<transactionManager type="JDBC"/><!--事务管理-->
<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>
<mappers>
<mapper class="com.my.dao.TeacherMapper"/>
<mapper class="com.my.dao.StudentMapper"/>
</mappers>
</configuration>
driver=com.mysql.jdbc.Driver
url=jdbc:mysql://localhost:3306/mybatis?useSSL=true&userUnicode=true&characterEncoding=UTF-8
username=root
password=123456
测试类
import com.my.dao.TeacherMapper;
import com.my.pojo.Teacher;
import com.my.utils.MybatisUtils;
import org.apache.ibatis.session.SqlSession;
public class MyTest {
public static void main(String[] args) {
SqlSession sqlSession = MybatisUtils.getSqlSession();
TeacherMapper mapper = sqlSession.getMapper(TeacherMapper.class);
Teacher teacher = mapper.getTeacher(1);
System.out.println(teacher);
sqlSession.close();
}
}
pom配置
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<parent>
<artifactId>MyBatis-Study</artifactId>
<groupId>org.example</groupId>
<version>1.0-SNAPSHOT</version>
</parent>
<modelVersion>4.0.0</modelVersion>
<artifactId>mybatis-06</artifactId>
<dependencies>
<!-- https://mvnrepository.com/artifact/org.projectlombok/lombok -->
<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
<version>1.18.12</version>
</dependency>
</dependencies>
</project>
运行结果
标签：name,查询,tid,org,MyBatis,import,com,id,搭建 来源： https://blog.csdn.net/char_m/article/details/111465830
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