Day19——MyBatis自定义映射级联属性操作

喜欢ヅ旅行 2023-07-04 14:02 11阅读 0赞

# 一. 回顾 #

前面[Day18——准备部门表\_部门实体类\_维护关系][Day18]做好了环境搭建准备后，今天讲解MyBatis的自定义映射

### [前往免费下载源码][Link 1] ###

# 二. 例子 #

EmployeeMapperResultMap.java

package com.atguigu.mybatis.dao;
    
    import com.atguigu.mybatis.beans.Employee;
    
    public interface EmployeeMapperResultMap { 
    
    	public Employee selectEmployeeAndDept(Integer id);
    }

EmployeeMapperResultMap.xml

<?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.atguigu.mybatis.dao.EmployeeMapperResultMap">
    	
    	
    	
    	<select id="selectEmployeeAndDept" resultMap="myEmpAndDept">
    	      select e.id eid, e.last_name, e.email, e.gender, d.id did, d.dept_name
    	      from tbl_employee e, tbl_dept d
    	      where e.d_id = d.id and e.id = #{id}
    	</select>
    	
    	
    	<resultMap type="com.atguigu.mybatis.beans.Employee" id="myEmpAndDept">
    	     <id column="eid" property="id"/>
    	     <result column="last_name" property="lastName"/>
    	     <result column="email" property="email"/>
    	     <result column="gender" property="gender"/>
    	     <result column="did" property="dept.id"/>
    	     <result column="dept_name" property="dept.departmentName"/>
    	</resultMap>
    </mapper>

TestMyBatisResultMap.java

package com.atguigu.mybatis.test;
    
    import java.io.InputStream;
    import java.sql.Connection;
    import java.sql.PreparedStatement;
    import java.util.List;
    import java.util.Map;
    
    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 org.junit.Test;
    
    import com.atguigu.mybatis.beans.Employee;
    import com.atguigu.mybatis.dao.EmployeeMapper;
    import com.atguigu.mybatis.dao.EmployeeMapperResultMap;
    
    public class TestMyBatisResultMap { 
    
    	
    	@Test
    	public void testResultMapCascade() throws Exception { 
    		SqlSessionFactory ssf = getSqlSessionFactory();
    		SqlSession session = ssf.openSession();
    		
    		try { 
    			EmployeeMapperResultMap mapper = session.getMapper(EmployeeMapperResultMap.class);
    			Employee employee = mapper.selectEmployeeAndDept(1001);
    			System.out.println(employee);
    			
    			
    			session.commit();
    		} finally { 
    			// TODO: handle finally clause
    			session.close();
    		}
    	}
    	
    	public SqlSessionFactory getSqlSessionFactory() throws Exception { 
    		String resource = "mybatis-config.xml"; 
    		InputStream inputStream = 
    				Resources.getResourceAsStream(resource); 
    		SqlSessionFactory sqlSessionFactory = 
    				new SqlSessionFactoryBuilder().build(inputStream);
    		return sqlSessionFactory;
    	}
    	
    }

[Day18]: https://blog.csdn.net/qq_40634846/article/details/104264248
[Link 1]: https://me.csdn.net/download/qq_40634846