06_一对一和一对多

一. 一对一关系

1. 一对一的实体类

2. 一对一映射配置

二. 一对多关系

1. 一对多的实体类

2. 一对多映射配置

二. 一对一和一对多关系例子

1. 新建一个名为AssociationCollection的Java工程, 拷入相关jar包

2. 新建User.java

package com.lywgames.domain;import java.util.Date;public class User {private Integer id;private String name;private String sex;private Date birthday;private String address;public User() {  }public User(String name, String sex, Date birthday, String address) {this.name = name;this.sex = sex;this.birthday = birthday;this.address = address;}public User(Integer id, String name, String sex, Date birthday, String address) {this.id = id;this.name = name;this.sex = sex;this.birthday = birthday;this.address = address;}public Integer getId() {return id;}public void setId(Integer id) {this.id = id;}public String getName() {return name;}public void setName(String name) {this.name = name;}public String getSex() {return sex;}public void setSex(String sex) {this.sex = sex;}public Date getBirthday() {return birthday;}public void setBirthday(Date birthday) {this.birthday = birthday;}public String getAddress() {return address;}public void setAddress(String address) {this.address = address;}@Overridepublic String toString() {return "User [id=" + id + ", name=" + name + ", sex=" + sex + ", birthday=" + birthday + ", address=" + address+ "]";}}

3. 新建Order.java

package com.lywgames.domain;import java.io.Serializable;
import java.sql.Timestamp;public class Order implements Serializable {private static final long serialVersionUID = 1L;private Integer id;private Integer uid;private String number;private Timestamp createtime;public Order() { }public Order(Integer uid, String number, Timestamp createtime) {this.uid = uid;this.number = number;this.createtime = createtime;}public Order(Integer id, Integer uid, String number, Timestamp createtime) {this.id = id;this.uid = uid;this.number = number;this.createtime = createtime;}public Integer getId() {return id;}public void setId(Integer id) {this.id = id;}public Integer getUid() {return uid;}public void setUid(Integer uid) {this.uid = uid;}public String getNumber() {return number;}public void setNumber(String number) {this.number = number;}public Timestamp getCreatetime() {return createtime;}public void setCreatetime(Timestamp createtime) {this.createtime = createtime;}@Overridepublic String toString() {return "Order [id=" + id + ", number=" + number + ", createtime=" + createtime + "]";}
}

4. 新建OrderDetail.java

package com.lywgames.domain;import java.io.Serializable;/*** 订单详情* 一个订单对应一个用户*/
public class OrderDetail implements Serializable {private static final long serialVersionUID = 1L;private User user;private Order order;public User getUser() {return user;}public void setUser(User user) {this.user = user;}public Order getOrder() {return order;}public void setOrder(Order order) {this.order = order;}@Overridepublic String toString() {return "OrderDetail [\r\n\t" + user + ",\r\n\t" + order + "\r\n]";}
}

5. 新建UserOrderList.java

package com.lywgames.domain;import java.io.Serializable;
import java.util.List;/*** 用户订单列表* 一个用户对应多个订单*/
public class UserOrderList implements Serializable {private static final long serialVersionUID = 1L;private User user;private List<Order> orderList;public User getUser() {return user;}public void setUser(User user) {this.user = user;}public List<Order> getOrderList() {return orderList;}public void setOrderList(List<Order> orderList) {this.orderList = orderList;}@Overridepublic String toString() {String ol = "";for (Order order : orderList) {ol += ",\r\n\t" + order;}return "UserOrderList [\r\n\t" + user + ol + "\r\n]";}
}

6. 新建UserMapper.java

package com.lywgames.dao;import com.lywgames.domain.OrderDetail;
import com.lywgames.domain.UserOrderList;public interface UserMapper {public OrderDetail selectOrderDetailByOrderId(Integer id);public UserOrderList selectUserOrderListByUserId(Integer id);
}

7. 在和UserMapper.java接口同一目录下新建UserMapper.xml映射文件

9. 在src目录下新建SqlMapConfig.xml数据库配置文件

10. 新建Test.java

package com.lywgames;import java.io.InputStream;
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 com.lywgames.dao.UserMapper;
import com.lywgames.domain.OrderDetail;
import com.lywgames.domain.UserOrderList;public class Test {public static void main(String[] args) {SqlSession sqlSession = null;try {// 指定全局配置文件String resource = "SqlMapConfig.xml";// 读取配置文件InputStream inputStream = Resources.getResourceAsStream(resource);// 构建sqlSessionFactorySqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);// 获取sqlSessionsqlSession = sqlSessionFactory.openSession();UserMapper um = sqlSession.getMapper(UserMapper.class);OrderDetail od = um.selectOrderDetailByOrderId(1);System.out.println("----------一对一----------");System.out.println(od);UserOrderList uol = um.selectUserOrderListByUserId(4);System.out.println("----------一对多----------");System.out.println(uol);} catch (Exception e) {e.printStackTrace();} finally {if(sqlSession != null) {// 释放资源sqlSession.close();}}}
}

11. 查看user表数据

12. 查看order表数据

13. 运行项目

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