Mybatis 多对多

Mybatis-config.xml

<?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.how2java.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/how2java?characterEncoding=UTF-8"/>
                <property name="username" value="root"/>
                <property name="password" value="admin"/>
            </dataSource>
        </environment>
    </environments>
    <mappers>
        <mapper resource="com/how2java/pojo/Product.xml"/>
        <mapper resource="com/how2java/pojo/Order.xml"/>
        <mapper resource="com/how2java/pojo/OrderItem.xml"/>
    </mappers>
</configuration>

OrderItem.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.how2java.pojo">

    <insert id="addOrderItem" parameterType="OrderItem">
            insert into order_item_
                values(null,#{order.id},#{product.id},#{number})
        </insert>
    <insert id="deleteOrderItem" parameterType="OrderItem">
            delete from order_item_
                where oid = #{order.id} and pid = #{product.id}
        </insert>

</mapper>

Order.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.how2java.pojo">
    <resultMap type="Order" id="orderBean">
        <id column="oid" property="id" />
        <result column="code" property="code" />

        <collection property="orderItems" ofType="OrderItem">
            <id column="oiid" property="id" />
            <result column="number" property="number" />
            <association property="product" javaType="Product">
                <id column="pid" property="id"/>
                <result column="pname" property="name"/>
                <result column="price" property="price"/>
            </association>
        </collection>
    </resultMap>

    <select id="listOrder" resultMap="orderBean">
            select o.*,p.*,oi.*, o.id 'oid', p.id 'pid', oi.id 'oiid', p.name 'pname'
                from order_ o
                left join order_item_ oi    on o.id =oi.oid
                left join product_ p on p.id = oi.pid
        </select>

    <select id="getOrder" resultMap="orderBean">
            select o.*,p.*,oi.*, o.id 'oid', p.id 'pid', oi.id 'oiid', p.name 'pname'
                from order_ o
                left join order_item_ oi on o.id =oi.oid
                left join product_ p on p.id = oi.pid
            where o.id = #{id}
        </select>
</mapper>

Product.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.how2java.pojo">
    <resultMap type="Product" id="productBean">
        <id column="pid" property="id" />
        <result column="pname" property="name" />
        <result column="price" property="price" />

        <!-- 多对一的关系 -->
        <!-- property: 指的是属性名称, javaType：指的是属性的类型 -->
        <association property="category" javaType="Category">
            <id column="cid" property="id"/>
            <result column="cname" property="name"/>
        </association>
    </resultMap>

    <select id="listProduct" resultMap="productBean">
            select c.*, p.*, c.id 'cid', p.id 'pid', c.name 'cname', p.name 'pname'
                from category_ c
                left join product_ p on c.id = p.cid
        </select>
    <select id="getProduct" resultMap="productBean">
            select c.*, p.*, c.id 'cid', p.id 'pid', c.name 'cname', p.name 'pname'
                from category_ c
                left join product_ p on c.id = p.cid
            where p.id = #{id}
        </select>
</mapper>

OrderItem.java

package com.how2java.pojo;

public class OrderItem {
    private int id;
    private int number;
    private Order order;
    private Product product;
    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 Order getOrder() {
        return order;
    }
    public void setOrder(Order order) {
        this.order = order;
    }
    public Product getProduct() {
        return product;
    }
    public void setProduct(Product product) {
        this.product = product;
    }

}

Order.java

package com.how2java.pojo;

import java.util.List;

public class Order {
    private int id;
    private String code;

    List<OrderItem> orderItems;

    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;
    }

}

Product.java

package com.how2java.pojo;

public class Product {
    private int id;
    private String name;
    private float price;
    private Category category;

    public Category getCategory() {
        return category;
    }
    public void setCategory(Category category) {
        this.category = category;
    }
    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 + "]";
    }

}

Category.java

package com.how2java.pojo;

import java.util.List;

public class Category {
    private int id;
    private String name;
    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;
    }

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

}

Mybatis.java

package com.how2java.pojo;

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;

public class TestMybatis {

    public static void main(String[] args) throws IOException {
        String resource = "mybatis-config.xml";
        InputStream inputStream = Resources.getResourceAsStream(resource);
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
        SqlSession session = sqlSessionFactory.openSession();

        listOrder(session);

        session.commit();
        session.close();

    }

    private static void listOrder(SqlSession session) {
        List<Order> os = session.selectList("listOrder");
        for (Order o : os) {
            System.out.println(o.getCode());
            List<OrderItem> ois= o.getOrderItems();
            for (OrderItem oi : ois) {
                System.out.format("\t%s\t%f\t%d%n", oi.getProduct().getName(),oi.getProduct().getPrice(),oi.getNumber());
            }
        }
    }
}