13.级联一对多

位置：在接口对应的映射文件里面配置
1.对多
	1)关联表的slq需要自己写
	2)配置
		1)collection
			a)property:一的一方中保存多一方的集合名称
			b)ofType:多的一方的类型
2.对一
	1)关联表的sql需要自己写
	2)配置
		1)association
			a)property:多的一方中保存一的方的属性名称
			b)javaType:一的一方的类型
3.细节问题
	1)关联查询的时候两种表的id都一样要取别名
	2)在做批量插入的时候不要在循环里面访问数据库

　例子：

0.数据库

1.创建项目

2.建包建配置文件

   com.qf.entity

   com.qf.dao

   com.qf.mapper

   com.qf.utils

mybatis-config.xml  

3.con.qf.entity包中创建实体类

package com.pxf.entity;

import java.util.ArrayList;
import java.util.List;

public class Customer {
	private Integer id;
	private String name;

	private List<OrderInfo> orderInfos;

	public Integer getId() {
		return id;
	}

	public void setId(Integer id) {
		this.id = id;
	}

	public String getName() {
		return name;
	}

	public void setName(String name) {
		this.name = name;
	}

	public List<OrderInfo> getOrderInfos() {
		return orderInfos;
	}

	public void setOrderInfos(List<OrderInfo> orderInfos) {
		this.orderInfos = orderInfos;
	}

	@Override
	public String toString() {
		return "Customer [id=" + id + ", name=" + name + ", orderInfos=" + orderInfos + "]";
	}
}

package com.pxf.entity;

public class OrderInfo {
	private Integer id;
	private String orderName;
	private Customer customer;

	public Integer getId() {
		return id;
	}

	public void setId(Integer id) {
		this.id = id;
	}

	public String getOrderName() {
		return orderName;
	}

	public void setOrderName(String orderName) {
		this.orderName = orderName;
	}

	public Customer getCustomer() {
		return customer;
	}

	public void setCustomer(Customer customer) {
		this.customer = customer;
	}

	@Override
	public String toString() {
		return "OrderInfo [id=" + id + ", orderName=" + orderName + ", customer=" + customer + "]";
	}

}

　　

4.con.qf.dao包中创建接口

package com.pxf.dao;

import com.pxf.entity.Customer;

public interface ICustomerDao {
	public int add(Customer customer);

	public Customer getCustomerById(Integer id);
}

　　

package com.pxf.dao;

import java.util.List;

import com.pxf.entity.OrderInfo;

public interface IOrderInfoDao {
	public int add(List<OrderInfo> orderInfos);

	public OrderInfo getOrderInfoById(Integer id);
}

　　

5.配置jdbc.properties配置文件

jdbc.url =jdbc:mysql://localhost:3306/1708_mybatis
jdbc.name=root
jdbc.password=root
jdbc.driver=com.mysql.jdbc.Driver　

配置mybatis-config.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">
<configuration>

	<!-- 加载属性文件 
		resource:本地资源文件
	-->
	<properties resource="jdbc.properties"></properties>

	<typeAliases>
			<package name="com.pxf.entity"/>
	</typeAliases>

	<environments default="development">
		<environment id="development">
			<transactionManager type="JDBC" />
			<dataSource type="POOLED">
				<property name="driver" value="${jdbc.driver}" />
				<property name="url" value="${jdbc.url}" />
				<property name="username" value="${jdbc.name}" />
				<property name="password" value="${jdbc.password}" />
			</dataSource>
		</environment>
	</environments>
	
</configuration>

　　

6.com.qf.mapper包创建接口的映射文件

<?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">
<mapper namespace="com.pxf.dao.ICustomerDao">
	<resultMap type="customer" id="customerMap">
		<id column="cid" property="id" />
		<result column="name" property="name" />
		
		<!-- 配置一对多关系 -->
		<!-- 
			property:一的一方中保存多一方的集合名称
			ofType:多的一方的类型
		 -->
		<collection property="orderInfos" ofType="orderInfo">
			<id column="oid" property="id" />
			<result column="order_name" property="orderName" />
            
            <!-- 配置多对一的关系 -->
			<!-- 
				property:多的一方中保存一的方的属性名称
				javaType:一的一方的类型
			 -->
            <association property="customer" javaType="customer">
               <id column="cid" property="id"/>
               <result column="name" property="name"/>
            </association>
		</collection>
		
	</resultMap>
   
   <insert id="add" parameterType="customer" useGeneratedKeys="true" keyProperty="id">
      insert into t_customer(name) values(#{name})
   </insert>
   
   <select id="getCustomerById" resultMap="customerMap">
      SELECT
			c.id AS cid,
			c. NAME,
			o.id AS oid,
			o.order_name
		FROM
			t_customer c
		LEFT JOIN t_order o ON (c.id = o.customer_id)
		WHERE
			c.id = #{id} 
   </select>

</mapper>

　　

<?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.pxf.dao.IOrderInfoDao">

 <insert id="add" parameterType="orderInfo">
   insert into t_order(order_name,customer_id) 
   values
    <foreach collection="list" item="o" separator=",">
      (#{o.orderName},#{o.customer.id})
    
    </foreach>
 
 </insert>
 
</mapper>

　　

7.在mybatis-config.xml里面读取Mapper文件

        <!-- Mapper文件 -->
	<mappers>
		<mapper resource="com/pxf/mapper/ICustomerDao.xml" />
		<mapper resource="com/pxf/mapper/IOrderInfoDao.xml" />
	</mappers>
	

8.com.qf.util工具类

package com.pxf.utils;

import java.io.IOException;
import java.io.InputStream;

import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;

public class SqlSessionFactoryUtils {
	
	private static SqlSessionFactory sqlSessionFactory;

	public static SqlSessionFactory getSqlSessionFactory() {
		if (sqlSessionFactory == null) {
			initSqlSessionFactory();
		}
		return sqlSessionFactory;

	}

	private static void initSqlSessionFactory() {

		InputStream inputStream = null;
		try {
			// 1.指定配置文件
			inputStream = Resources.getResourceAsStream("mybatis-config.xml");
			// 2.赋值操作o
			synchronized (SqlSessionFactoryUtils.class) {

				if (sqlSessionFactory == null) {

					sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
				}
			}

		} catch (IOException e) {
			e.printStackTrace();
		} finally {
			if (inputStream != null) {
				try {
					inputStream.close();
				} catch (IOException e) {
					e.printStackTrace();
				}
			}
		}
	}

}

　　

9.测试类

package com.qf.dao;

import java.util.ArrayList;
import java.util.List;

import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.junit.Test;

import com.pxf.dao.ICustomerDao;
import com.pxf.dao.IOrderInfoDao;
import com.pxf.entity.Customer;
import com.pxf.entity.OrderInfo;
import com.pxf.utils.SqlSessionFactoryUtils;

public class CustomerDaoTest {

	@Test
	public void testCustomerAdd() {
		SqlSessionFactory sqlSessionFactory = SqlSessionFactoryUtils.getSqlSessionFactory();
		SqlSession sqlSession = sqlSessionFactory.openSession();
		ICustomerDao customerDao = sqlSession.getMapper(ICustomerDao.class);
		IOrderInfoDao orderInfoDao = sqlSession.getMapper(IOrderInfoDao.class);
		
		Customer customer =new Customer();
		customer.setName("李相爱");
		
		OrderInfo orderInfo =new OrderInfo();
		orderInfo.setOrderName("订单A");
		
		OrderInfo orderInfo2 =new OrderInfo();
		orderInfo.setOrderName("订单B");
		
		customerDao.add(customer);
		
		orderInfo.setCustomer(customer);
		orderInfo.setCustomer(customer);
		
		List<OrderInfo> orderInfos=new ArrayList<OrderInfo>();
		orderInfos.add(orderInfo);
		orderInfos.add(orderInfo2);
		
		orderInfoDao.add(orderInfos);
		sqlSession.commit();
		sqlSession.close();
	}
	
	
	@Test
	public void testGetCustomerById() {
	SqlSessionFactory sqlSessionFactory = SqlSessionFactoryUtils.getSqlSessionFactory();
	SqlSession sqlSession = sqlSessionFactory.openSession();
	ICustomerDao customerDao = sqlSession.getMapper(ICustomerDao.class);
	Customer customer = customerDao.getCustomerById(3);
	System.out.println(customer);
	sqlSession.commit();
	sqlSession.close();
	
	
	}
}