Mybatis 多表查詢及查詢結果映射

使用MyBatis這一強大的框架可以解決很多賦值的問題，其中對於子配置文件中的小細節有很多需要注意的地方，使用這個框架后主要就是對於配置文件的編寫和配置。
今天我寫了一個多表查詢，表的基本結構如下：
用戶表t_user:用戶編號uid，賬號account，昵稱nickname，性別gender
訂單表t_order:訂單編號oid，下單時間gen_time，總價total_price，用戶編號user_id
訂單詳情表:詳情編號id，訂單編號order_id,商品編號product_id,下單數量amount
商品表:商品編號pid，商品名稱pname，商品價格price，商品描述description
其中訂單表user_id是外鍵對應用戶表的uid;訂單詳情表的order_id,product_id分別對應訂單表的oid和商品表的pid

 

程序中分別定義了四個實體來映射這四個表
查詢語句是：

SELECT  
    uid,  
    account,  
    nickname,  
    gender,  
    oid,  
    gen_time,  
    total_price,  
    user_id,  
    id,  
    order_id,  
    product_id,  
    amount,  
    pid,  
    pname,  
    price,  
    description  
FROM  
    t_user  
JOIN t_order ON t_user.uid = t_order.user_id  
JOIN t_order_product ON t_order_product.order_id = t_order.oid  
JOIN t_product ON t_product.pid = t_order_product.product_id  
WHERE  
    uid = 1  

 

User類：

package cn.edu360.pojo;

import java.util.List;

public class User {
	private Long id;
	private String account;
	private String nickname;
	private String gender;
	private List<Order> orders;

	/*
	 * (non-Javadoc)
	 * 
	 * @see java.lang.Object#toString()
	 */
	@Override
	public String toString() {
		return "[用戶編號:" + id + ", 賬號:" + account + ", 昵稱:" + nickname + ", 性別:" + gender + ", 所下訂單:"
				+ orders + "]";
	}

	/**
	 * @return the orders
	 */
	public List<Order> getOrders() {
		return orders;
	}

	/**
	 * @param orders
	 *            the orders to set
	 */
	public void setOrders(List<Order> orders) {
		this.orders = orders;
	}

	public Long getId() {
		return id;
	}

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

	public String getAccount() {
		return account;
	}

	public void setAccount(String account) {
		this.account = account;
	}

	public String getNickname() {
		return nickname;
	}

	public void setNickname(String nickname) {
		this.nickname = nickname;
	}

	public String getGender() {
		return gender;
	}

	public void setGender(String gender) {
		this.gender = gender;
	}

}

　　

 

Order類：

 

package cn.edu360.pojo;

import java.util.Date;
import java.util.List;

public class Order {
    private Long id;
    private Date genTime;
    private Double totalPrice;
    private Long userId;
    private List<Orderitems> orderitems;

    /*
     * (non-Javadoc)
     * 
     * @see java.lang.Object#toString()
     */
    @Override
    public String toString() {
        return "訂單詳情 [訂單號:" + id + ", 下單時間:" + genTime + ", 訂單總價:" + totalPrice + ", 所含商品:" + orderitems + "]";
    }

    /**
     * @return the orderitems
     */
    public List<Orderitems> getOrderitems() {
        return orderitems;
    }

    /**
     * @param orderitems
     *            the orderitems to set
     */
    public void setOrderitems(List<Orderitems> orderitems) {
        this.orderitems = orderitems;
    }

    public Long getId() {
        return id;
    }

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

    public Date getGenTime() {
        return genTime;
    }

    public void setGenTime(Date genTime) {
        this.genTime = genTime;
    }

    public Double getTotalPrice() {
        return totalPrice;
    }

    public void setTotalPrice(Double totalPrice) {
        this.totalPrice = totalPrice;
    }

    public Long getUserId() {
        return userId;
    }

    public void setUserId(Long userId) {
        this.userId = userId;
    }

}

 

 

 

Orderitems類：

package cn.edu360.pojo;

import java.util.List;

public class Orderitems {
    private Long id;
    private Long oid;
    private Long pid;
    private Long amount;
    private List<Product> product;

    /*
     * (non-Javadoc)
     * 
     * @see java.lang.Object#toString()
     */
    @Override
    public String toString() {
        return "[數量:" + amount + product +"]" ;
    }

    /**
     * @return the product
     */
    public List<Product> getProduct() {
        return product;
    }

    /**
     * @param product
     *            the product to set
     */
    public void setProduct(List<Product> product) {
        this.product = product;
    }

    public Long getId() {
        return id;
    }

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

    public Long getOid() {
        return oid;
    }

    public void setOid(Long oid) {
        this.oid = oid;
    }

    public Long getPid() {
        return pid;
    }

    public void setPid(Long pid) {
        this.pid = pid;
    }

    public Long getAmount() {
        return amount;
    }

    public void setAmount(Long amount) {
        this.amount = amount;
    }
}

 

 

Product類：

package cn.edu360.pojo;

public class Product {
    private Long id;
    private String name;
    private Double price;
    private String description;

    /*
     * (non-Javadoc)
     * 
     * @see java.lang.Object#toString()
     */
    @Override
    public String toString() {
        return "[商品編號:" + id + ", 商品名稱:" + name + ", 價格:" + price + ", 描述:" + description + "]";
    }

    public Long getId() {
        return id;
    }

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

    public String getName() {
        return name;
    }

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

    public Double getPrice() {
        return price;
    }

    public void setPrice(Double price) {
        this.price = price;
    }

    public String getDescription() {
        return description;
    }

    public void setDescription(String description) {
        this.description = description;
    }

}

 

 

用戶的實現接口，根據輸入ID號查詢當前用戶的信息以及他的歷史訂單和訂單里所包含的商品明細

也即Dao層接口：

package cn.edu360.mapper;

import cn.edu360.pojo.User;

public interface UserMapper {

    public User getByIdWithOrdersWithProducts(Long id);
}

 

 

 用戶接口的配置文件

<?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="cn.edu360.mapper.UserMapper">
    <resultMap type="user" id="userOrderitemsResultMap">
        <id property="id" column="uid" />
        <result property="account" column="account" />
        <result property="nickname" column="nickname" />
        <result property="gender" column="gender" />
        <collection property="orders" ofType="Order">
            <id property="id" column="oid" />
            <result property="genTime" column="gen_time" />
            <result property="totalPrice" column="total_price" />
            <result property="userId" column="user_id" />
            <collection property="orderitems" ofType="Orderitems">
                <id property="id" column="id" />
                <result property="oid" column="order_id" />
                <result property="pid" column="product_id" />
                <result property="amount" column="amount" />
                <collection property="product" ofType="Product">
                    <id property="id" column="pid" />
                    <result property="name" column="pname" />
                    <result property="price" column="price" />
                    <result property="description" column="description" />
                </collection>
            </collection>
        </collection>
    </resultMap>
    <select id="getByIdWithOrdersWithProducts" resultMap="userOrderitemsResultMap"
        parameterType="long">
        SELECT
        uid,
        account,
        nickname,
        gender,
        oid,
        gen_time,
        total_price,
        user_id,
        id,
        order_id,
        product_id,
        amount,
        pid,
        pname,
        price,
        description
        FROM
        t_user
        JOIN t_order ON t_user.uid = t_order.user_id
        JOIN t_order_product ON t_order_product.order_id = t_order.oid
        JOIN t_product ON t_product.pid = t_order_product.product_id
        WHERE
        uid = 1
    </select>
</mapper>

 

核心配置文件

<?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>
        <typeAlias type="cn.edu360.pojo.User" alias="User"/>
        <typeAlias type="cn.edu360.pojo.Product" alias="Product"/>
        <typeAlias type="cn.edu360.pojo.Order" alias="Order"/>
        <typeAlias type="cn.edu360.pojo.Orderitems" alias="Orderitems"/>
    </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/storemybatis?characterEncoding=utf-8" />
                <property name="username" value="root" />
                <property name="password" value="12580" />
            </dataSource>
        </environment>
    </environments>
    <!--  <mappers>
        <mapper resource="ProductMapper.xml"/>
    </mappers>  -->
    <mappers>
        <package name="cn.edu360.mapper"/>
    </mappers>
</configuration>

JUnit測試方法：

package cn.edu360.mapper;

import java.io.IOException;

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.Before;
import org.junit.Test;

import cn.edu360.pojo.User;

public class UserMapperTest {

    private SqlSessionFactory sqlSessionFactory = null;
    
    @Before
    public void init() throws IOException {
        sqlSessionFactory = new SqlSessionFactoryBuilder().build(Resources.getResourceAsStream("SqlMapConfig.xml"));
    }

    @Test
    public void testGetByIdWithOrdersWithProducts() {
        SqlSession sqlSession = sqlSessionFactory.openSession();
        UserMapper userImpl = sqlSession.getMapper(UserMapper.class);
        User user = userImpl.getByIdWithOrdersWithProducts(1L);
        System.out.println(user);
        sqlSession.close();
    }

}

基本上面的就可以輸出當前用戶的信息和所有歷史訂單以及訂單的商品詳情。