MyBatis——一对一

一个订单对应一个用户

1、Java 实体

public class OrderInfo {
    private Integer id;
    private Date ordertime;
    private Double total;
    private Integer uid;
    private UserInfo user;

    public Integer getId() {
        return id;
    }
    public void setId(Integer id) {
        this.id = id;
    }
    public Date getOrdertime() {
        return ordertime;
    }
    public void setOrdertime(Date ordertime) {
        this.ordertime = ordertime;
    }
    public Double getTotal() {
        return total;
    }
    public void setTotal(Double total) {
        this.total = total;
    }
    public Integer getUid() {
        return uid;
    }
    public void setUid(Integer uid) {
        this.uid = uid;
    }

    public UserInfo getUser() {
        return user;
    }
    public void setUser(UserInfo user) {
        this.user = user;
    }
    @Override
    public String toString() {
        return "OrderInfo{" +
                "id=" + id +
                ", ordertime=" + ordertime +
                ", total=" + total +
                ", uid=" + uid +
                ", user=" + user +
                '}';
    }
}

public class UserInfo {
    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 "UserInfo{" +
                "id=" + id +
                ", username='" + username + '\'' +
                '}';
    }
}

2、mapper 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.deppon.mapper.OrderMapper">

    <resultMap id="orderMap" type="com.deppon.domain.OrderInfo">
        <result property="id" column="id"></result>
        <result property="ordertime" column="ordertime"></result>
        <result property="total" column="total"></result>
        <association property="user" javaType="com.deppon.domain.UserInfo">
            <result property="id" column="uid"></result>
            <result property="username" column="username"></result>
        </association>
    </resultMap>

    <select id="findOrderList" resultMap="orderMap">
        select * from user u,orderinfo o where u.id = o.uid;
    </select>
</mapper>

3、测试类

public class TestOrderMapperUtil {

    private OrderMapper orderMapper;

    @Before
    public void before() throws IOException {
        String path = "SqlConfig.xml";
        InputStream inputStream = Resources.getResourceAsStream(path);
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
        SqlSession session = sqlSessionFactory.openSession(true);
        orderMapper = session.getMapper(OrderMapper.class);
    }

    @Test
    public void test(){
        List<OrderInfo> orderList = orderMapper.findOrderList();
        System.out.println(orderList);
    }
}