Hibernate5.2之一对一外键关联(五)

Hibernate5.2之一对一外键关联(五)

一.简介

　　上篇文章中笔者介绍了Hibernate关联关系中的一对一外键关联，本篇博客将介绍一对一外键关联。其实我们回过头想一想，外键关联其实就是一对多关联关系中将多的一方简化为一个，就是我们本文所要介绍的一对一的外键关联。

二.外键关联

2.1数据库表的创建

create table people (

    id varchar2(255 char) not null,

    name varchar2(255 char),

    sex varchar2(255 char),

    primary key (id)

);

create table cards (

    id varchar2(255 char) not null,

    card_num varchar2(255 char),

    people_id varchar2(255 char),

    primary key (id)

);

2.2 hbm文件的方式

public class People {

    private String id;

    private String name;

    private String sex;

    private IdCard idCard;

    //setter and getter

}

public class IdCard {

    private String id;

    private String cardNum;

    private People people;

    //setter and getter

}

People.hbm.xml

<?xml version="1.0" encoding="UTF-8"?>

<!DOCTYPE hibernate-mapping PUBLIC

        "-//Hibernate/Hibernate Mapping DTD 3.0//EN"

        "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">

<hibernate-mapping>

    <class name="com.demo.hibernate.one2one.People" table="people">

        <id name="id" type="string">

            <generator class="uuid"></generator>

        </id>

        <property name="name" type="string" column="name"></property>

        <property name="sex" type="string" column="sex"></property>

        <one-to-one name="idCard" class="com.demo.hibernate.one2one.IdCard" cascade="all" property-ref="people"></one-to-one>

    </class>

</hibernate-mapping>

IdCard.hbm.xml

<?xml version="1.0" encoding="UTF-8"?>

<!DOCTYPE hibernate-mapping PUBLIC

        "-//Hibernate/Hibernate Mapping DTD 3.0//EN"

        "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">

<hibernate-mapping>

    <class name="com.demo.hibernate.one2one.IdCard" table="cards">

        <id name="id" type="string" column="id">

            <generator class="uuid"></generator>

        </id>

        <property name="cardNum" type="string" column="card_num"></property>

        <many-to-one name="people" class="com.demo.hibernate.one2one.People" column="people_id" unique="true"></many-to-one>

    </class>

</hibernate-mapping>

2.3 注解的方式

People.java

@Entity

@Table(name="people")

public class People {

    @Id

    @Column(name="id")

    @GenericGenerator(name="uuidGenerator", strategy="uuid")

    @GeneratedValue(generator="uuidGenerator")

    private String id;

    @Column(name="name")

    private String name;

    @Column(name="sex")

    private String sex;

    @OneToOne(cascade={CascadeType.ALL}, fetch=FetchType.LAZY, mappedBy="people")

    private IdCard idCard;

    //setter and getter

}

IdCard.java

@Entity

@Table(name="cards")

public class IdCard {

    @Id

    @Column(name="id")

    @GenericGenerator(name="uuidGenerator", strategy="uuid")

    @GeneratedValue(generator="uuidGenerator")

    private String id;

    @Column(name="card_num")

    private String cardNum;

    @ManyToOne(fetch=FetchType.LAZY)

    @JoinColumn(name="people_id")

    private People people;

    //setter and getter

}

2.4 代码测试

A.保存

@Test

public void save(){

    Transaction tx = session.beginTransaction();

    People people = new People();

    people.setName("AAA");

    people.setSex("男");

    IdCard idCard = new IdCard();

    idCard.setCardNum("889900");

    idCard.setPeople(people);

    people.setIdCard(idCard);

    session.save(people);

    tx.commit();
}

B.get

@Test

public void get(){

    People people = session.get(People.class, "402882e6564a70fa01564a70fbd40000");

    System.out.println("此时已经发送了SQL语句");

    System.out.println(people.getName() + "::" + people.getSex());

    IdCard idCard = people.getIdCard();

    System.out.println(idCard.getCardNum());

}

C.load

@Test

public void load(){

    People people = session.load(People.class, "402882e6564a70fa01564a70fbd40000");

    System.out.println("此时没有发送任何的SQL语句");

    System.out.println(people.getName() + "::" + people.getSex());

    System.out.println("=============");

    IdCard idCard = people.getIdCard();

    System.out.println(idCard.getCardNum());

}

D.delete

@Test

public void delete(){

    People people = new People();

    people.setId("402882e6564a7c1501564a7c16d80000");

    IdCard card = new IdCard();

    card.setId("402882e6564a7c1501564a7c16e50001");

    people.setIdCard(card);

    Transaction tx = session.beginTransaction();

    session.delete(people);

    tx.commit();
}

E.update

@Test

public void update(){

    Transaction tx = session.beginTransaction();

    People people = new People();

    people.setId("402882e6564a70fa01564a70fbd40000");

    people.setName("YYYY");

    people.setSex("男");

    session.update(people);

    tx.commit();

}

巴特西

Hibernate5.2之一对一外键关联(五)

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