hibernate（六）一对一映射

关系映射是指对象之间的关系，并不是指数据库的关系，关系映射是解决当对象处于以下关系之一时，数据库表该如何映射的问题

(一)一对一单向外键关联

1、注解方式配置

创建一个Husband类和Wife类

Husband类:(getWife方法上加注解OneToOne)

package cn.orlion.hibernate.model;import javax.persistence.Entity;import javax.persistence.GeneratedValue;import javax.persistence.Id;import javax.persistence.OneToOne;@Entitypublic class Husband {    private int id;    private String name;    private Wife wife;    @Id  @GeneratedValue  public int getId() {    return id;  }  public void setId(int id) {    this.id = id;  }  public String getName() {    return name;  }  public void setName(String name) {    this.name = name;  }  @OneToOne
　　@JoinColumn(name="wifeId")//默认生成的外键id是wife_id在这里使用JoinColumn注解name属性指定为wifeId  public Wife getWife() {    return wife;  }  public void setWife(Wife wife) {    this.wife = wife;  }}

Wife类

package cn.orlion.hibernate.model;import javax.persistence.Entity;import javax.persistence.GeneratedValue;import javax.persistence.Id;@Entitypublic class Wife {  private int id;    private String name;    @Id  @GeneratedValue  public int getId() {    return id;  }  public void setId(int id) {    this.id = id;  }  public String getName() {    return name;  }  public void setName(String name) {    this.name = name;  }}

然后创建一个测试类HibernateMappingTest

package cn.orlion.hibernate.model;import org.hibernate.cfg.AnnotationConfiguration;import org.hibernate.tool.hbm2ddl.SchemaExport;import org.junit.Test;public class HibernateORMappingTest {  @Test  public void testSchemaExport(){        new SchemaExport(new AnnotationConfiguration().configure()).create(true , true);  }}

运行testSchemaExport可以在控制台看到建表语句:

2、

首先创建一个Student类和StuIdCard(学生证)

Student类：

package cn.orlion.hibernate.model;public class Student {  private int id;    private String name;    private String sex;  public int getId() {    return id;  }  public void setId(int 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;  }}

StuIdCard：
package cn.orlion.hibernate.model;public class StuIdCard { private int id; private int num; private Student student; public int getId() { return id; } public void setId(int id) { this.id = id; } public int getNum() { return num; } public void setNum(int num) { this.num = num; } public Student getStudent() { return student; } public void setStudent(Student student) { this.student = student; }}

然后创建两个配置文件Student.hbm.
<??><!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN" "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd"><hibernate-mapping package="cn.orlion.hibernate.model"> <class name="cn.orlion.hibernate.model.Student"> <id name="id"> <generator class="native"></generator> </id> <property name="name"></property> <property name="sex"></property> </class></hibernate-mapping>

StuIdCard.hbm.
<??><!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN" "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd"><hibernate-mapping package="cn.orlion.hibernate.model"> <class name="cn.orlion.hibernate.model.StuIdCard"> <id name="id"> <generator class="native"></generator> </id> <property name="num" /> <many-to-one name="student" column="studentId" unique="true"></many-to-one>  </class></hibernate-mapping>

然后运行测试类HibernateORMappingTest类的testSchemaExport方法可以在控制台看到建表语句:
(二)一对一双向外键关联
1、注解方式设置
双向外键关联注解方式设置是在wife类中添加husband属性，在getHusband()方法上添加注解@OneToOne(mappedBy="wife")//mappedBy="wife"表示Husband中wife属性已经做映射了，不用管当前类的设置（不再从wife表中生成指向husband的外键）注:如果不写mappedBy="wife"会在wife表中生成一个husband_id外键，这是多余的。
Wife类：
package cn.orlion.hibernate.model;import javax.persistence.Entity;import javax.persistence.GeneratedValue;import javax.persistence.Id;import javax.persistence.OneToOne;@Entitypublic class Wife { private int id; private String name; private Husband husband; @Id @GeneratedValue public int getId() { return id; } public void setId(int id) { this.id = id; } public String getName() { return name; } public void setName(String name) { this.name = name; } @OneToOne(mappedBy="wife")//mappedBy="wife"表示Husband中wife属性已经做映射了，不用管当前类的设置（不再从wife表中生成指向husband的外键） public Husband getHusband() { return husband; } public void setHusband(Husband husband) { this.husband = husband; } }

2、
在Student.hbm.
Student类：
package cn.orlion.hibernate.model;public class Student { private int id; private String name; private String sex; private StuIdCard stuIdCard; public int getId() { return id; } public void setId(int 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 StuIdCard getStuIdCard() { return stuIdCard; } public void setStuIdCard(StuIdCard stuIdCard) { this.stuIdCard = stuIdCard; } }

Student.hbm.
<??><!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN" "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd"><hibernate-mapping package="cn.orlion.hibernate.model"> <class name="cn.orlion.hibernate.model.Student"> <id name="id"> <generator class="native"></generator> </id> <property name="name"></property> <property name="sex"></property> <one-to-one name="stuIdCard" property-ref="student"></one-to-one>   </class></hibernate-mapping>

注：一对一单向和双向在数据库中表现没有区别

主键关联是指的一个表的主键和另外一个表的主键关联
外键关联是指的一个表的主键和另外一个表的非主键关联

（三）一对一单向主键关联
创建Student类
package cn.orlion.hibernate.model;public class Student { private int id; private String name; private String sex; public int getId() { return id; } public void setId(int 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; }}

StuIdCard类：
package cn.orlion.hibernate.model;public class StuIdCard { private int id; private int num; private Student student; public int getId() { return id; } public void setId(int id) { this.id = id; } public int getNum() { return num; } public void setNum(int num) { this.num = num; } public Student getStudent() { return student; } public void setStudent(Student student) { this.student = student; }}

Student.hbm.
<??><!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN" "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd"><hibernate-mapping package="cn.orlion.hibernate.model"> <class name="cn.orlion.hibernate.model.Student"> <id name="id"> <generator class="native"></generator> </id> <property name="name"></property> <property name="sex"></property> </class></hibernate-mapping>

StuIdCard.hbm.
<??><!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN" "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd"><hibernate-mapping package="cn.orlion.hibernate.model"> <class name="cn.orlion.hibernate.model.StuIdCard"> <id name="id"> <generator class="foreign"> <param name="property">student</param> </generator> </id> <property name="num" /> <one-to-one name="student" constrained="true"></one-to-one>  </class></hibernate-mapping>

运行：
（四）一对一双向主键关联
注解方式配置:
Husband类：
package cn.orlion.hibernate.model;import javax.persistence.Entity;import javax.persistence.GeneratedValue;import javax.persistence.Id;import javax.persistence.JoinColumn;import javax.persistence.OneToOne;import javax.persistence.PrimaryKeyJoinColumn;@Entitypublic class Husband { private int id; private String name; private Wife wife; @Id @GeneratedValue public int getId() { return id; } public void setId(int id) { this.id = id; } public String getName() { return name; } public void setName(String name) { this.name = name; } @OneToOne @PrimaryKeyJoinColumn public Wife getWife() { return wife; } public void setWife(Wife wife) { this.wife = wife; }}

Wife类：
package cn.orlion.hibernate.model;import javax.persistence.Entity;import javax.persistence.GeneratedValue;import javax.persistence.Id;import javax.persistence.OneToOne;@Entitypublic class Wife { private int id; private String name; private Husband husband; @Id @GeneratedValue public int getId() { return id; } public void setId(int id) { this.id = id; } public String getName() { return name; } public void setName(String name) { this.name = name; } @OneToOne @PrimaryKeyJoinColumn
　　 public Husband getHusband() { return husband; } public void setHusband(Husband husband) { this.husband = husband; } }

（五）联合主键映射
Wife类：
package cn.orlion.hibernate.model;import javax.persistence.Entity;import javax.persistence.GeneratedValue;import javax.persistence.Id;import javax.persistence.IdClass;@Entity@IdClass(WifePK.class)public class Wife { private int id; private String name; private String age; @Id public int getId() { return id; } public void setId(int id) { this.id = id; } @Id public String getName() { return name; } public void setName(String name) { this.name = name; } public String getAge() { return age; } public void setAge(String age) { this.age = age; } }

WifePK：
package cn.orlion.hibernate.model;public class WifePK { private int id; private String name; public int getId() { return id; } public void setId(int id) { this.id = id; } public String getName() { return name; } public void setName(String name) { this.name = name; }}

Husband类：
package cn.orlion.hibernate.model;import javax.persistence.Entity;import javax.persistence.GeneratedValue;import javax.persistence.Id;import javax.persistence.JoinColumn;import javax.persistence.JoinColumns;import javax.persistence.OneToOne;@Entitypublic class Husband { private int id; private String name; private Wife wife; @Id @GeneratedValue public int getId() { return id; } public void setId(int id) { this.id = id; } public String getName() { return name; } public void setName(String name) { this.name = name; } @OneToOne @JoinColumns( { @JoinColumn(name="wifeId" , referencedColumnName="id"), @JoinColumn(name="wifeName" , referencedColumnName="name") } ) public Wife getWife() { return wife; } public void setWife(Wife wife) { this.wife = wife; }}

运行结果：

原标题：hibernate（六）一对一映射
关键词：Hibernate

Hibernate

*特别声明：以上内容来自于网络收集，著作权属原作者所有，如有侵权，请联系我们： admin#shaoqun.com （#换成@）。

海外仓的模式有哪几种？跨境卖家如何做好海外仓？：https://www.goluckyvip.com/news/711.html
超大件货物家具沙发床垫国际海运到新西兰加拿大温哥华双清：https://www.goluckyvip.com/news/7110.html
Shopee上货用什么工具？有什么上架规则？：https://www.goluckyvip.com/news/7111.html
头部产品月流水3000w+、出海厂商布局拉美东南亚，这个消除子类还有多少潜力？| 年末复盘：https://www.goluckyvip.com/news/71115.html
TikTok明年GMV目标500亿美元；亚马逊调整2024费率；北美尾程物流服务商UniUni融资丨跨境电商周报：https://www.goluckyvip.com/news/71116.html
亚马逊商家盯上了TikTok：https://www.goluckyvip.com/news/71117.html
重庆风景名胜？：https://www.vstour.cn/a/404236.html
卓欧毕雪酒店推荐：https://www.vstour.cn/a/404237.html