Mybatis注解——一对多

最新推荐文章于 2025-09-08 15:23:54 发布

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本文介绍了一个基于MyBatis的关联查询实现方案，包括数据库建表语句、实体类定义、Mapper接口及测试类等，实现了从数据库中获取用户及其订单信息。

1、数据库建表语句

CREATE TABLE `user` (
  `id` int(11) DEFAULT NULL,
  `username` varchar(50) DEFAULT NULL
);


CREATE TABLE `orderinfo` (
  `id` int(11) DEFAULT NULL,
  `ordertime` datetime DEFAULT NULL,
  `total` decimal(8,2) DEFAULT NULL,
  `uid` int(11) DEFAULT NULL
);

2、实体

public class UserInfo {

    private Integer id;

    private String username;

    private List<OrderInfo> orderInfoList;


    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;
    }

    public List<OrderInfo> getOrderInfoList() {
        return orderInfoList;
    }

    public void setOrderInfoList(List<OrderInfo> orderInfoList) {
        this.orderInfoList = orderInfoList;
    }

    @Override
    public String toString() {
        return "UserInfo{" +
                "id=" + id +
                ", username='" + username + '\'' +
                ", orderInfoList=" + orderInfoList +
                '}';
    }
}

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 +
                '}';
    }
}

3、Mapper 接口java代码

public interface UserMapper {

    @Select("select * from user")
    @Results({
            @Result(property = "id",column = "id"),
            @Result(property = "username",column = "username"),
            @Result(property = "orderInfoList",column = "id",javaType = List.class,
            many = @Many(select = "com.deppon.mapper.OrderMapper.findOrderListByUid"))
    })
    public List<UserInfo> findAll();
}

public interface OrderMapper {

    @Results({
            @Result(property = "id",column = "id"),
            @Result(property = "ordertime",column="ordertime"),
            @Result(property = "total",column="total"),
            @Result(property = "user",column = "uid",javaType = UserInfo.class,
                    one = @One(select = "com.deppon.mapper.UserMapper.findUserById"))
    })

    @Select("select * from orderinfo where uid = #{id}")
    List<OrderInfo> findOrderListByUid(Integer id);

}

4、测试类

public class TestOrderMapperUtil {

    private OrderMapper orderMapper;

    private UserMapper userMapper;

    @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);
        userMapper = session.getMapper(UserMapper.class);
    }


    @Test
    public void test(){
        List<UserInfo> userInfoList = userMapper.findAll();
        for(UserInfo userInfo:userInfoList){
            System.out.println(userInfo);
        }
    }
}