一对一单向外键关联

Annotation:@One2One @JoinColumn
xml:<many-to-one unique>

一般情况大致如下图中所设计，在一个表中设计另一个表的外键；

下图就是在 husband 表中 设计了 wife 的外键关联。

Husband 类：

package com.bjsxt.hibernate;

import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.OneToOne;

@Entity
public class Husband {
    
    private Integer id;
    
    private String name;

    private Wife wife;
    
    @Id
    @GeneratedValue
    public Integer getId() {
        return id;
    }

    public String getName() {
        return name;
    }

    @OneToOne//一对一的关系
    @JoinColumn(name="wifeId")//外键ID
    public Wife getWife() {
        return wife;
    }

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

    public void setName(String name) {
        this.name = name;
    }

    public void setWife(Wife wife) {
        this.wife = wife;
    }
}

Wife 类

package com.bjsxt.hibernate;

import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;

@Entity
public class Wife {
    private Integer id;
    
    private String name;

    @Id
    @GeneratedValue
    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;
    }
}

加上hibernate.cfg.xml配置：

<mapping class="com.bjsxt.hibernate.Husband"/>
<mapping class="com.bjsxt.hibernate.Wife"/>

SchemaExport代码：

　　@Test
    public void testSchemaExport(){
        new SchemaExport(new AnnotationConfiguration().configure()).create(false, true);
    }

如下图，数据库会自动生成两个表并且建立 husband 表到 wife 表的外键关联

XML 中对一对一单向关联进行配置：

学生(Student) 和 学生证 (StudentIdCard)

Student

package com.bjsxt.hibernate;

public class Student {
    
    private Integer id;
    
    private String name;
    
    private Integer age;
    
    private String sex;
    
    private boolean good;

    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 Integer getAge() {
        return age;
    }

    public void setAge(Integer age) {
        this.age = age;
    }

    public String getSex() {
        return sex;
    }

    public void setSex(String sex) {
        this.sex = sex;
    }

    public boolean isGood() {
        return good;
    }

    public void setGood(boolean good) {
        this.good = good;
    }
    
}

StudentIdCard

package com.bjsxt.hibernate;

public class StudentIdCard {

    private Integer id;
    
    private String num;
    
    private Student student;

    public Integer getId() {
        return id;
    }

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

    public String getNum() {
        return num;
    }

    public void setNum(String num) {
        this.num = num;
    }

    public Student getStudent() {
        return student;
    }

    public void setStudent(Student student) {
        this.student = student;
    }
    
}

在 StudentIdCard 中加了 student 对象，在StudentIdCard.hbm.xml中的配置，进行一对一的单向关联：

<many-to-one name="student" column="studentId" unique="true"></many-to-one>

 所需jar包链接: https://pan.baidu.com/s/1i5fxsjF 密码: qw9u

代码链接: https://pan.baidu.com/s/1dFzin3z 密码: b7e2