SSM16.3【Mybatis：通过注解实现Mybatis的复杂映射开发之一对一查询】

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

package com.haifei.domain;

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

public class User {

    private int id;
    private String username;
    private String password;
    private Date birthday;


    public Date getBirthday() {
        return birthday;
    }

    public void setBirthday(Date birthday) {
        this.birthday = birthday;
    }

    public int getId() {
        return id;
    }

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

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }

    @Override
    public String toString() {
        return "User{" +
                "id=" + id +
                ", username='" + username + '\'' +
                ", password='" + password + '\'' +
                ", birthday=" + birthday +
                '}';
    }
}

package com.haifei.domain;

import java.util.Date;

public class Order {

    private int id;
    private Date ordertime;
    private double total;


    //当前订单属于哪一个用户
    private User user;
    public User getUser() {
        return user;
    }
    public void setUser(User user) {
        this.user = user;
    }

    public int getId() {
        return id;
    }

    public void setId(int 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;
    }


    @Override
    public String toString() {
        return "Order{" +
                "id=" + id +
                ", ordertime=" + ordertime +
                ", total=" + total +
                ", user=" + user +
                '}';
    }
}

package com.haifei.mapper;

import com.haifei.domain.Order;
import com.haifei.domain.User;
import org.apache.ibatis.annotations.One;
import org.apache.ibatis.annotations.Result;
import org.apache.ibatis.annotations.Results;
import org.apache.ibatis.annotations.Select;

import java.util.List;

public interface OrderMapper {

    /*@Select("select *,o.id oid from orders o,user u where o.uid=u.id")
    @Results({
            @Result(column = "oid", property = "id"),
            @Result(column = "ordertime",property = "ordertime"),
            @Result(column = "total",property = "total"),
            @Result(column = "uid", property = "user.id"),
            @Result(column = "username", property = "user.username"),
            @Result(column = "password", property = "user.password"),
            @Result(column = "birthday", property = "user.birthday")
    })*/
    @Select("select * from orders")
    @Results({
            @Result(column = "id", property = "id"),
            @Result(column = "ordertime",property = "ordertime"),
            @Result(column = "total",property = "total"),
            @Result(
                    property = "user", //要封装的属性名称
                    column = "uid", //根据哪个字段去查询user表的数据
                    javaType = User.class, //要封装的实体类型
                    one = @One(select = "com.haifei.mapper.UserMapper.findById")
                    //select属性 代表查询那个接口的方法获得数据
            )
    })
    public List<Order> findAll();

}

 

 

 

 

package com.haifei.test;

import com.haifei.domain.Order;
import com.haifei.mapper.OrderMapper;
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 java.io.IOException;
import java.io.InputStream;
import java.util.List;

public class MybatisTest2 {

    private OrderMapper mapper;

    @Before
    public void before() throws IOException {
        InputStream resourceAsStream = Resources.getResourceAsStream("sqlMapConfig.xml");
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(resourceAsStream);
        SqlSession sqlSession = sqlSessionFactory.openSession(true); //true-->事务自动提交
        mapper = sqlSession.getMapper(OrderMapper.class);
    }

    /**
     * 一对一查询
     */
    @Test
    public void testFindAll(){
        List<Order> orderList = mapper.findAll();
        for (Order order : orderList) {
            System.out.println(order);
        }
        /*
        Order{id=1, ordertime=Thu Jan 01 08:00:02 CST 1970, total=3000.0, user=User{id=1, username='zhangsan', password='123', birthday=Sat Jul 24 20:00:29 CST 2021}}
        Order{id=2, ordertime=Thu Jan 01 08:00:02 CST 1970, total=1000.0, user=User{id=2, username='lisi', password='345', birthday=Sat Jul 24 20:00:29 CST 2021}}
        Order{id=3, ordertime=Thu Jan 01 08:00:02 CST 1970, total=344.0, user=User{id=1, username='zhangsan', password='123', birthday=Sat Jul 24 20:00:29 CST 2021}}
        Order{id=4, ordertime=Thu Jan 01 08:00:02 CST 1970, total=455.0, user=User{id=2, username='lisi', password='345', birthday=Sat Jul 24 20:00:29 CST 2021}}
        Order{id=5, ordertime=Thu Jan 01 08:00:02 CST 1970, total=100.0, user=User{id=3, username='tom', password='abc', birthday=Sat Jul 24 20:00:29 CST 2021}}
         */
    }

}