mybitas一对一单向查询(eclipse)

最新推荐文章于 2025-05-21 17:06:37 发布

不生产代码的码农

最新推荐文章于 2025-05-21 17:06:37 发布

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文章标签： mybatis eclipse java

本文链接：https://blog.youkuaiyun.com/qq_35586240/article/details/145566794

版权

工程结构

表结构

mybatis.xml 配置文件

<?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">

</dataSource>

</environment>

</environments>

</mappers>

</configuration>

ClassesMap.xml 实体类映射文件

<?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">

select * from classes c,teacher t where c.teacher_id=t.t_id and c.c_id=#{id}

</select>

</association>

</resultMap>

</mapper>

缓存工厂类

package com.my.daoimpl;

import java.io.IOException;

import java.io.Reader;

import org.apache.ibatis.io.Resources;

import org.apache.ibatis.session.SqlSession;

import org.apache.ibatis.session.SqlSessionFactory;

import org.apache.ibatis.session.SqlSessionFactoryBuilder;

public class SuperDao {

//读取配置mybatis总配置文件

private static Reader reader=null;

private static SqlSessionFactory factory=null;

static{

try {

reader = Resources.getResourceAsReader("mybatis.xml");

//创建缓存工厂

SqlSessionFactoryBuilder builder = new SqlSessionFactoryBuilder();

factory = builder.build(reader);

} catch (IOException e) {

e.printStackTrace();

}

public static SqlSession getSession(){

return factory.openSession();

}

带外联实体类

package com.my.pojo;

public class Classes {

int id;

String c_name;

// 包含类的属性

Teacher teacher;

public Teacher getTeacher() {

return teacher;

}

public void setTeacher(Teacher teacher) {

this.teacher = teacher;

}

public int getId() {

return id;

}

public void setId(int id) {

this.id = id;

}

public String getC_name() {

return c_name;

}

public void setC_name(String c_name) {

this.c_name = c_name;

}

实体类

package com.my.pojo;

public class Teacher {

int id;

String t_name;

public int getId() {

return id;

}

public void setId(int id) {

this.id = id;

}

public String getT_name() {

return t_name;

}

public void setT_name(String t_name) {

this.t_name = t_name;

}

Dao层

package com.my.daoimpl;

import java.io.IOException;

import java.io.Reader;

import org.apache.ibatis.io.Resources;

import org.apache.ibatis.session.SqlSession;

import org.apache.ibatis.session.SqlSessionFactory;

import org.apache.ibatis.session.SqlSessionFactoryBuilder;

public class SuperDao {

//读取配置mybatis总配置文件

private static Reader reader=null;

private static SqlSessionFactory factory=null;

static{

try {

reader = Resources.getResourceAsReader("mybatis.xml");

//创建缓存工厂

SqlSessionFactoryBuilder builder = new SqlSessionFactoryBuilder();

factory = builder.build(reader);

} catch (IOException e) {

e.printStackTrace();

}

public static SqlSession getSession(){

return factory.openSession();

}

测试类

package com.my.test;

import org.apache.ibatis.session.SqlSession;

import com.my.daoimpl.SuperDao;

import com.my.pojo.Classes;

public class TestOenToOen {

/**

* @param args

public static void main(String[] args) {

// TODO Auto-generated method stub

//获取session对象

SqlSession session=SuperDao.getSession();

//第一个参数为要调用的方法为pojo实体类映射文件内mapper标签的namespace，

//加上要调用的方法的ID

//第二个参数为传入的值

Classes c=session.selectOne("com.my.pojo.ClassesMap.getClassesTeacherMap", 2);

System.out.println("班级："+c.getC_name()+"\t"+"老师："+c.getTeacher().getT_name());

}