目录结构

数据库

1、product_表

插入数据：

建表sql文：

use mybatistest1;

create table product_(
id int NOT NULL AUTO_INCREMENT,
name varchar(30)  DEFAULT NULL,
price float  DEFAULT 0,
cid int ,
PRIMARY KEY (id)
)AUTO_INCREMENT=1 DEFAULT CHARSET=utf8;

3、创建order_表


建表sql：

create table order_(
	id int(11) NOT NULL AUTO_INCREMENT,
	code VARCHAR(32) DEFAULT NULL,
	PRIMARY KEY(id)
)ENGINE=MyISAM AUTO_INCREMENT=1 DEFAULT CHARSET=utf8;
 

4、order_item表


建表sql：

CREATE table order_item_(
	id int(11) not null auto_increment,
	oid int,
	pid int,
	number int,
	PRIMARY KEY(id)
)AUTO_INCREMENT=1 DEFAULT CHARSET=utf8;

代码

Order实体类

package com.mybatis.pojo;

import java.util.List;

public class Order {
	private int id;
	private String code;
	
	List<OrderItem> orderitems;   //一对多

	public int getId() {
		return id;
	}

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

	public String getCode() {
		return code;
	}

	public void setCode(String code) {
		this.code = code;
	}

	public List<OrderItem> getOrderitems() {
		return orderitems;
	}

	public void setOrderitems(List<OrderItem> orderitems) {
		this.orderitems = orderitems;
	}
	
	
}

OrderItem实体类

package com.mybatis.pojo;

public class OrderItem {
	private int id;
	private int number;
	//private Order order;
	private Product product;    //多对一
	/*public Order getOrder() {
		return order;
	}
	public void setOrder(Order order) {
		this.order = order;
	}*/
	public int getId() {
		return id;
	}
	public void setId(int id) {
		this.id = id;
	}
	public int getNumber() {
		return number;
	}
	public void setNumber(int number) {
		this.number = number;
	}
	public Product getProduct() {
		return product;
	}
	public void setProduct(Product product) {
		this.product = product;
	}
}

Product实体类

package com.mybatis.pojo;

public class Product {
    private int id;
    private String name;
    private float price;
    
    public int getId() {
        return id;
    }
	public void setId(int id) {
        this.id = id;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public float getPrice() {
        return price;
    }
    public void setPrice(float price) {
        this.price = price;
    }
    @Override
    public String toString() {
        return "Product [id=" + id + ", name=" + name + ", price=" + price + "]";
    }
 
}

OrdeMapper类

package com.mybatis.mapper;

import java.util.List;

import org.apache.ibatis.annotations.One;
import org.apache.ibatis.annotations.Result;
import org.apache.ibatis.annotations.Results;
import org.apache.ibatis.annotations.Select;

import com.mybatis.pojo.OrderItem;

public interface OrderItemMapper {
	@Select("select * from order_item_ where oid=#{oid}")
	@Results({
		//@Result(property="id",column="id"),
		//@Result(property="number",column="number"),
		@Result(property="product",column="pid",one=@One(select="com.mybatis.mapper.ProductMapper.getByProduct"))
	})
	public List<OrderItem> getByOrder(int oid);
}

OrderItemMapper类

package com.mybatis.mapper;

import java.util.List;

import org.apache.ibatis.annotations.Many;
import org.apache.ibatis.annotations.Result;
import org.apache.ibatis.annotations.Results;
import org.apache.ibatis.annotations.Select;

import com.mybatis.pojo.Order;

public interface OrderMapper {
	@Select("select * from order_")
	@Results({
		//@Result(property="id",column="id"),
		//@Result(property="code",column="code"),
		@Result(property="orderitems",column="id",many=@Many(select="com.mybatis.mapper.OrderItemMapper.getByOrder"))
	})    //column当作参数传入Many中的方法
	public List<Order> listOrder();
}

ProductMapper类

package com.mybatis.mapper;

import java.util.List;

import org.apache.ibatis.annotations.One;
import org.apache.ibatis.annotations.Result;
import org.apache.ibatis.annotations.Results;
import org.apache.ibatis.annotations.Select;

import com.mybatis.pojo.Product;

public interface ProductMapper {
	
	@Select("select * from product_ where id=#{id}")
	
	public Product getByProduct(int id);
}

测试主类

package com.mybatis;

import java.io.IOException;
import java.io.InputStream;
import java.util.List;
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 com.mybatis.mapper.OrderMapper;
import com.mybatis.pojo.*;

public class testMybatis {
	public static void main(String[] args) throws IOException {
        String resource = "mybatis-config.xml"; //获取全局配置信息
        InputStream inputStream = Resources.getResourceAsStream(resource); //全局配置信息装入输入流
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream); //建立sql会话工厂，将输入流装入
        SqlSession session=sqlSessionFactory.openSession(); //开启一个会话
        
        //CategoryMapper categorymapper=session.getMapper(CategoryMapper.class);
        OrderMapper ordermapper=session.getMapper(OrderMapper.class);
        
        listAll(ordermapper);
     
              
        session.commit();  //更新到数据库
        session.close();  
    }
	
	private static void listAll(OrderMapper mapper) {
		List<Order> os=mapper.listOrder();
		for(Order o:os) {
			System.out.println(o.getCode());
			List<OrderItem> ois=o.getOrderitems();
			if(null!=ois) {
				for(OrderItem oi:ois) {
					System.out.format("\t%s\t%f\t%d%n", oi.getProduct().getName(),oi.getProduct().getPrice(),oi.getNumber());
				}
			}
		}
		
	}

	 
		
}

全局配置文件

<?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>
    <typeAliases>
      <package name="com.mybatis.pojo"/>
    </typeAliases>
    <environments default="development">
        <environment id="development">
            <transactionManager type="JDBC"/>
            <dataSource type="POOLED">
            <property name="driver" value="com.mysql.jdbc.Driver"/>
            <property name="url" value="jdbc:mysql://localhost:3306/mybatistest1?characterEncoding=UTF-8"/>
            <property name="username" value="root"/>
            <property name="password" value="zhao8888"/>
            </dataSource>
        </environment>
    </environments>
    <mappers>
       
        
        <mapper class="com.mybatis.mapper.OrderMapper"/>
        <mapper class="com.mybatis.mapper.OrderItemMapper"/>
        <mapper class="com.mybatis.mapper.ProductMapper"/>
        
       
    </mappers>
</configuration>

结果

过程和总结

Order类包括OrderItem类list集合------>一对多

OrderItem类包括Product类list集合------->多对一

一对多对一都等于多对多
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