hibernate 关系映射之 单向外键关联一对一

这里的关系指的是对象与对象之间的关系

注解方式单向关联一对一：

//这个类描述的husband是一个对应一个wife的

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 int id;
    private String name;
    private Wife wife;
    @Id
    @GeneratedValue
    public int getId() {
        return id;
    }
   
    public String getName() {
        return name;
    }
   @OneToOne
   @JoinColumn(name="wifeId")//指定生成的表该外键的字段名，不指定会自动生成系统默认的字段名wife_id
    public Wife getWife() {
        return wife;
    }
    public void setId(int id) {
        this.id = id;
    }
    public void setName(String name) {
        this.name = name;
    }
    public void setWife(Wife wife) {
        this.wife = wife;
    }
   
}

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

@Entity
public 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;
    }
   
}

测试类：

package com.bjsxt.hibernate;

import java.util.Date;

import org.hibernate.Query;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.cfg.AnnotationConfiguration;
import org.hibernate.tool.hbm2ddl.SchemaExport;
import org.junit.AfterClass;
import org.junit.BeforeClass;
import org.junit.Test;

public class HibernateORMappingTest {
    private static SessionFactory sessionFactory;
   
    //@BeforeClass
    public static void beforeClass() {
            sessionFactory = new AnnotationConfiguration().configure().buildSessionFactory();
    }
    //@AfterClass
    public static void afterClass() {
        sessionFactory.close();
    }

@Test
    public void testSchemaExport() {
        new SchemaExport(new AnnotationConfiguration().configure()).create(false, true);//配置了log4j可以看到生成语句
    }
   
    public static void main(String[] args) {
        beforeClass();
    }
}

配置文件

<hibernate-configuration>

……

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

</session-factory>

</hibernate-configuration>

</session-factory>

</hibernate-configuration>

xml方式：

StuIdCard.hbm.xml

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
        "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
        "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">

<hibernate-mapping>
    <class name="com.bjsxt.hibernate.StuIdCard">
        <id name="id">
            <generator class="native"></generator>
        </id>
       
        <property name="num"/>
        <many-to-one name="student" column="studentId" unique="true"></many-to-one><!-- unique唯一的，manytoone是多对一，加上unique就是一对一了，表示StuIdCard单向一对一对应 student，name设为本类的student属性（StuIdCard类中要定义private Student student属性），column表示用哪个字段作为外键关联字段 -->
    </class>
   
</hibernate-mapping>