MyBatis复杂映射开发之一对一查询

Terwer 后端开发 MyBatis评论33字数 4245阅读14分9秒阅读模式

一对一查询需求

用户表和订单表的关系为:一个用户可以有多个订单,一个订单只能从属于一个用户文章源自浅海拾贝-https://blog.terwergreen.com/mybatis-complex-mapping-development-one-to-one-query.html

MyBatis复杂映射开发之一对一查询文章源自浅海拾贝-https://blog.terwergreen.com/mybatis-complex-mapping-development-one-to-one-query.html

一对一查询需求:查询一个订单,同时查询出该订单所对应的用户文章源自浅海拾贝-https://blog.terwergreen.com/mybatis-complex-mapping-development-one-to-one-query.html

对应的sql语句:select * from orders o,user u where o.uid=u.id文章源自浅海拾贝-https://blog.terwergreen.com/mybatis-complex-mapping-development-one-to-one-query.html

查询结果如下:文章源自浅海拾贝-https://blog.terwergreen.com/mybatis-complex-mapping-development-one-to-one-query.html

id ordertime total uid id username password birthday
1 2022-03-17 17:15:33 3000 1 1 lucy 123 2022-03-17 17:15:56
2 2022-03-17 17:15:33 4000 1 1 lucy 123 2022-03-17 17:15:56
3 2022-03-17 17:15:33 5000 2 2 tom 123 2022-03-17 17:15:56

需求分析

MyBatis复杂映射开发之一对一查询文章源自浅海拾贝-https://blog.terwergreen.com/mybatis-complex-mapping-development-one-to-one-query.html

MyBatis复杂映射开发之一对一查询文章源自浅海拾贝-https://blog.terwergreen.com/mybatis-complex-mapping-development-one-to-one-query.html

具体实现

创建User和Order实体

  • User

    文章源自浅海拾贝-https://blog.terwergreen.com/mybatis-complex-mapping-development-one-to-one-query.html

    文章源自浅海拾贝-https://blog.terwergreen.com/mybatis-complex-mapping-development-one-to-one-query.html

    /**
    * 用户信息
    *
    * @name: User
    * @author: terwer
    * @date: 2022-05-08 17:41
    */
    class User {
      var id: Int? = null
      var username: String? = null
      override fun toString(): String {
          return "User{" +
                  "id=" + id +
                  ", username='" + username + '\'' +
                  '}'
      }
    }
    

    文章源自浅海拾贝-https://blog.terwergreen.com/mybatis-complex-mapping-development-one-to-one-query.html

    文章源自浅海拾贝-https://blog.terwergreen.com/mybatis-complex-mapping-development-one-to-one-query.html

    /**
    * 用户信息
    *
    * @name: User
    * @author: terwer
    * @date: 2022-03-17 17:41
    **/
    public class User {
      private Integer id;
      private String username;
    
      public Integer getId() {
          return id;
      }
    
      public void setId(Integer id) {
          this.id = id;
      }
    
      public String getUsername() {
          return username;
      }
    
      public void setUsername(String username) {
          this.username = username;
      }
    
      @Override
      public String toString() {
          return "User{" +
                  "id=" + id +
                  ", username='" + username + '\'' +
                  '}';
      }
    }
    

    文章源自浅海拾贝-https://blog.terwergreen.com/mybatis-complex-mapping-development-one-to-one-query.html

    文章源自浅海拾贝-https://blog.terwergreen.com/mybatis-complex-mapping-development-one-to-one-query.html

  • Order文章源自浅海拾贝-https://blog.terwergreen.com/mybatis-complex-mapping-development-one-to-one-query.html

    文章源自浅海拾贝-https://blog.terwergreen.com/mybatis-complex-mapping-development-one-to-one-query.html

    文章源自浅海拾贝-https://blog.terwergreen.com/mybatis-complex-mapping-development-one-to-one-query.html

    /**
    * 订单
    *
    * @name: Order
    * @author: terwer
    * @date: 2022-05-08 17:42
    */
    class Order {
      var id: Int? = null
      var orderTime: String? = null
      var total: Double? = null
    
      // 代表当前订单属于哪一个用户
      var user: User? = null
      override fun toString(): String {
          return "Order{" +
                  "id=" + id +
                  ", orderTime='" + orderTime + '\'' +
                  ", total=" + total +
                  ", user=" + user +
                  '}'
      }
    }
    

    文章源自浅海拾贝-https://blog.terwergreen.com/mybatis-complex-mapping-development-one-to-one-query.html

    文章源自浅海拾贝-https://blog.terwergreen.com/mybatis-complex-mapping-development-one-to-one-query.html

    /**
    * 订单
    *
    * @name: Order
    * @author: terwer
    * @date: 2022-03-17 17:42
    **/
    public class Order {
      private Integer id;
      private String orderTime;
      private Double total;
    
      // 代表当前订单属于哪一个用户
      private User user;
    
      public Integer getId() {
          return id;
      }
    
      public void setId(Integer id) {
          this.id = id;
      }
    
      public String getOrderTime() {
          return orderTime;
      }
    
      public void setOrderTime(String orderTime) {
          this.orderTime = orderTime;
      }
    
      public Double getTotal() {
          return total;
      }
    
      public void setTotal(Double total) {
          this.total = total;
      }
    
      public User getUser() {
          return user;
      }
    
      public void setUser(User user) {
          this.user = user;
      }
    
      @Override
      public String toString() {
          return "Order{" +
                  "id=" + id +
                  ", orderTime='" + orderTime + '\'' +
                  ", total=" + total +
                  ", user=" + user +
                  '}';
      }
    }
    

    文章源自浅海拾贝-https://blog.terwergreen.com/mybatis-complex-mapping-development-one-to-one-query.html

    文章源自浅海拾贝-https://blog.terwergreen.com/mybatis-complex-mapping-development-one-to-one-query.html

创建OrderMapper接口

文章源自浅海拾贝-https://blog.terwergreen.com/mybatis-complex-mapping-development-one-to-one-query.html

文章源自浅海拾贝-https://blog.terwergreen.com/mybatis-complex-mapping-development-one-to-one-query.html

/**
 * 订单映射
 *
 * @name: IUserMapper
 * @author: terwer
 * @date: 2022-05-08 17:54
 */
interface OrderMapper {
    /**
     * 查询订单同时查询订单所属用户
     * @return
     */
    fun findOrderAndUser(): List<Order?>?
}

文章源自浅海拾贝-https://blog.terwergreen.com/mybatis-complex-mapping-development-one-to-one-query.html

文章源自浅海拾贝-https://blog.terwergreen.com/mybatis-complex-mapping-development-one-to-one-query.html

/**
 * 订单映射
 *
 * @name: IUserMapper
 * @author: terwer
 * @date: 2022-03-17 17:54
 **/
public interface OrderMapper {
    /**
     * 查询订单同时查询订单所属用户
     * @return
     */
    public List<Order> findOrderAndUser();
}

文章源自浅海拾贝-https://blog.terwergreen.com/mybatis-complex-mapping-development-one-to-one-query.html

文章源自浅海拾贝-https://blog.terwergreen.com/mybatis-complex-mapping-development-one-to-one-query.html

配置OrderMapper.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.terwergreen.mapper.OrderMapper">
    <resultMap id="orderMap" type="com.terwergreen.pojo.Order">
        <result property="id" column="id"></result>
        <result property="orderTime" column="ordertime"></result>
        <result property="total" column="total"></result>

        <association property="user" javaType="com.terwergreen.pojo.User">
            <result property="id" column="uid"></result>
            <result property="username" column="username"></result>
        </association>
    </resultMap>

    <!-- resultMap:手动配置实体属性与表字段的映射关系 -->
    <select id="findOrderAndUser" resultMap="orderMap">
        select * from orders o,user u where o.uid=u.id
    </select>
</mapper>

另外一种配置方法文章源自浅海拾贝-https://blog.terwergreen.com/mybatis-complex-mapping-development-one-to-one-query.html

 <mapper namespace="com.terwergreen.mapper.OrderMapper">
    <resultMap id="orderMap" type="com.terwergreen.pojo.Order">
       <result property="id" column="id"></result>
        <result property="orderTime" column="ordertime"></result>
        <result property="total" column="total"></result>

        <result property="user.id" column="uid"></result>
        <result property="user.username" column="username"></result>
    </resultMap>

    <!-- resultMap:手动配置实体属性与表字段的映射关系 -->
    <select id="findOrderAndUser" resultMap="orderMap">
        select * from orders o,user u where o.uid=u.id
    </select>
</mapper>

测试结果

文章源自浅海拾贝-https://blog.terwergreen.com/mybatis-complex-mapping-development-one-to-one-query.html

文章源自浅海拾贝-https://blog.terwergreen.com/mybatis-complex-mapping-development-one-to-one-query.html

@Test
@Throws(IOException::class)
fun test1() {
    val resourceAsStream = Resources.getResourceAsStream("sqlMapConfig.xml")
    val sqlSessionFactory = SqlSessionFactoryBuilder().build(resourceAsStream)
    val sqlSession = sqlSessionFactory.openSession()
    val orderMapper = sqlSession.getMapper(OrderMapper::class.java)
    val orderList = orderMapper.findOrderAndUser()
    for (order in orderList) {
        println(order)
    }
}

文章源自浅海拾贝-https://blog.terwergreen.com/mybatis-complex-mapping-development-one-to-one-query.html

文章源自浅海拾贝-https://blog.terwergreen.com/mybatis-complex-mapping-development-one-to-one-query.html

@Test
public void test1() throws IOException {
    InputStream resourceAsStream = Resources.getResourceAsStream("sqlMapConfig.xml");
    SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(resourceAsStream);

    SqlSession sqlSession = sqlSessionFactory.openSession();
    OrderMapper orderMapper = sqlSession.getMapper(OrderMapper.class);

    List<Order> orderList = orderMapper.findOrderAndUser();
    for (Order order : orderList) {
        System.out.println(order);
    }
}

文章源自浅海拾贝-https://blog.terwergreen.com/mybatis-complex-mapping-development-one-to-one-query.html

文章源自浅海拾贝-https://blog.terwergreen.com/mybatis-complex-mapping-development-one-to-one-query.html

MyBatis复杂映射开发之一对一查询文章源自浅海拾贝-https://blog.terwergreen.com/mybatis-complex-mapping-development-one-to-one-query.html

文章更新历史
2022/05/08 feat:新增Kotlin支持 文章源自浅海拾贝-https://blog.terwergreen.com/mybatis-complex-mapping-development-one-to-one-query.html

文章源自浅海拾贝-https://blog.terwergreen.com/mybatis-complex-mapping-development-one-to-one-query.html
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