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hibernate 关系映射之单向外键关联一对一

news 来源：原创 2024/5/8 1:35:49

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>

……

</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>
    </class>

</hibernate-mapping>