hibernate annotation 双向 one-to-one 注解

「爱情、让人受尽委屈。」 2022-07-21 00:19 155阅读 0赞

环境：

Hibernate 3.3.1 
    Maven 3.0.4 
    MySQL 5.5.13 
    Myeclipse 8.6.1

建表语句：

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DROP TABLE IF EXISTS `t_card`;
    CREATE TABLE `t_card` (
      `cardId` int(10) unsigned NOT NULL AUTO_INCREMENT,
      `cardNumber` char(18) NOT NULL,
      PRIMARY KEY (`cardId`)
    ) ENGINE=InnoDB AUTO_INCREMENT=2 DEFAULT CHARSET=gb2312;
    
    INSERT INTO `t_card` VALUES ('1', '440911199008011122');

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DROP TABLE IF EXISTS `t_person`;
    CREATE TABLE `t_person` (
      `personId` int(10) unsigned NOT NULL AUTO_INCREMENT,
      `personName` varchar(15) NOT NULL,
      `cid` int(10) unsigned NOT NULL,
      PRIMARY KEY (`personId`)
    ) ENGINE=InnoDB AUTO_INCREMENT=2 DEFAULT CHARSET=gb2312;
    
    INSERT INTO `t_person` VALUES ('1', 'fancy', '1');

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Person.java

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package com.fancy.po;
    
    import javax.persistence.CascadeType;
    import javax.persistence.Entity;
    import javax.persistence.GeneratedValue;
    import javax.persistence.GenerationType;
    import javax.persistence.Id;
    import javax.persistence.JoinColumn;
    import javax.persistence.OneToOne;
    import javax.persistence.Table;
    /**
     * -----------------------------------------
     * @文件: Person.java
     * @作者: fancy
     * @邮箱: fancyzero@yeah.net
     * @时间: 2012-6-10
     * @描述: 实体类
     * -----------------------------------------
     */
    /**
     * @Entity 声明一个类为实体Bean
     * @Table(name = "xx")指定实体类映射的表,如果表名和实体类名一致,可以不指定
     */
    @Entity
    @Table(name = "t_person")
    public class Person {
    
        private Integer personId;
        private String  personName;
        private Card    card;
        /**
         * @Id 映射主键属性,这里采用uuid的主键生成策略
          * @GeneratedValue —— 注解声明了主键的生成策略。该注解有如下属性
          * strategy 指定生成的策略,默认是GenerationType. AUTO
         * GenerationType.AUTO 主键由程序控制
          * GenerationType.TABLE 使用一个特定的数据库表格来保存主键
          * GenerationType.IDENTITY 主键由数据库自动生成,主要是自动增长类型
          * GenerationType.SEQUENCE 根据底层数据库的序列来生成主键，条件是数据库支持序列
          * generator 指定生成主键使用的生成器
          */
        @Id
        @GeneratedValue(strategy = GenerationType.AUTO)
        public Integer getPersonId() {
            return personId;
        }
        /**
         * @OneToOne：一对一关联
          * cascade：级联,它可以有有五个值可选,分别是：
          * CascadeType.PERSIST：级联新建
          * CascadeType.REMOVE : 级联删除
          * CascadeType.REFRESH：级联刷新
          * CascadeType.MERGE  ： 级联更新
          * CascadeType.ALL    ： 以上全部四项
          * @JoinColumn:主表外键字段
          * cid：Person所映射的表中的一个字段
          */
        @OneToOne(cascade = CascadeType.ALL)
        @JoinColumn(name = "cid")
        public Card getCard() {
            return card;
        }
        public String getPersonName() {
            return personName;
        }
        public void setPersonId(Integer personId) {
            this.personId = personId;
        }
        public void setPersonName(String personName) {
            this.personName = personName;
        }
        public void setCard(Card card) {
            this.card = card;
        }
    }

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Card.java

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package com.fancy.po;
    
    import javax.persistence.Entity;
    import javax.persistence.GeneratedValue;
    import javax.persistence.GenerationType;
    import javax.persistence.Id;
    import javax.persistence.OneToOne;
    import javax.persistence.Table;
    /**
     * -----------------------------------------
     * @文件: Card.java
     * @作者: fancy
     * @邮箱: fancyzero@yeah.net
     * @时间: 2012-6-10
     * @描述: 实体类
     * -----------------------------------------
     */
    @Entity
    @Table(name = "t_card")
    public class Card {
    
        private Integer cardId;
        private String  cardNumber;
        private Person  person;
        
        @Id
        @GeneratedValue(strategy = GenerationType.AUTO)
        public Integer getCardId() {
            return cardId;
        }
        /**
         * @OneToOne：一对一关联
          * mappedBy = "card"：意思是说这里的一对一配置参考了card
         * card又是什么呢?card是Person类中的getCard(),注意不是Person类中的
          * card属性,Person类中的OneToOne配置就是在getCard()方法上面配的.
         * 如果Person类中的getCard()方法改成getIdCard(),其他不变的话,
         * 这里就要写成：mappedBy = "idCard"
         */
        @OneToOne(mappedBy = "card")
        public Person getPerson() {
            return person;
        }
        public String getCardNumber() {
            return cardNumber;
        }
        public void setCardId(Integer cardId) {
            this.cardId = cardId;
        }
        public void setCardNumber(String cardNumber) {
            this.cardNumber = cardNumber;
        }
        public void setPerson(Person person) {
            this.person = person;
        }
    }

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pom.xml

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<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
      xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
      
      <modelVersion>4.0.0</modelVersion>
      <groupId>com.fancy</groupId>
      <artifactId>hibernate-annotation-on-to-one-example</artifactId>
      <version>0.0.1-SNAPSHOT</version>
      <packaging>jar</packaging>
      <name>hibernate-annotation-on-to-one-example</name>
      <url>http://maven.apache.org</url>
      <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
      </properties>
      
      <dependencies>
        
        <dependency>
          <groupId>org.hibernate</groupId>
          <artifactId>hibernate-entitymanager</artifactId>
          <version>3.3.1.ga</version>
        </dependency>
        
        <dependency>
          <groupId>org.hibernate</groupId>
          <artifactId>hibernate-annotations</artifactId>
          <version>3.3.1.GA</version>
        </dependency>
        
        <dependency>
          <groupId>mysql</groupId>
          <artifactId>mysql-connector-java</artifactId>
          <version>5.1.17</version>
        </dependency>
        <dependency>
          <groupId>junit</groupId>
          <artifactId>junit</artifactId>
          <version>3.8.1</version>
          <scope>test</scope>
        </dependency>
      </dependencies>
      
    </project>

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Test.java

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package com.fancy.test;
    
    import org.hibernate.Session;
    import org.hibernate.SessionFactory;
    import org.hibernate.cfg.AnnotationConfiguration;
    import org.hibernate.cfg.Configuration;
    import com.fancy.po.Card;
    import com.fancy.po.Person;
    /**
     * -----------------------------------------
     * @文件: Test.java
     * @作者: fancy
     * @邮箱: fancyzero@yeah.net
     * @时间: 2012-6-10
     * @描述: 测试类
     * -----------------------------------------
     */
    public class Test {
    
        public static void main(String[] args) {
            
            //读取hibernate配置,默认读取classpath下的hibernate.cfg.xml
            Configuration conf = new AnnotationConfiguration();    
            //构建session工厂
             SessionFactory sessionFactory = conf.configure().buildSessionFactory();
            //打开session
            Session session = sessionFactory.openSession();
            //开始事务
             session.beginTransaction();
            // * * * * * * * * * * * * * * * * * * * * * * * * * * * *
            //test1(session);    //测试 1
            //test2(session);    //测试 2
            test3(session);      //测试 3
            // * * * * * * * * * * * * * * * * * * * * * * * * * * * *
            //提交事务
             session.getTransaction().commit();
            //关闭session工厂
             sessionFactory.close();
           //关闭session
           session.close();
        }
        /**
         * 数据库初始值：
          * personName：fancy
         * cardNumber：440911199008011122
         */
        //测试方法1
        public static void test1(Session session){
            Person person = (Person)session.get(Person.class, 1); //发出Person和Card的select语句
             Card card = person.getCard();
            System.out.println(person.getPersonName());
            System.out.println(card.getCardNumber());
            person.setPersonName("fancy");            //与初始值一致
             card.setCardNumber("440911199008011122");//与初始值一致
             session.save(person);    //不发出sql语句
           //session.save(card);     //不发出sql语句
        }
        //测试方法2
        public static void test2(Session session){
            Person person = (Person)session.get(Person.class, 1); //发出Person和Card的select语句
             Card card = person.getCard();
            System.out.println(person.getPersonName());
            System.out.println(card.getCardNumber());
            person.setPersonName("fancyzero");        //与初始值不一致
             card.setCardNumber("440911199008011122");//与初始值一致
             session.save(person);    //发出Person的update语句,数据库中personName被修改,不发出Card的update语句
           //session.save(card);     //发出Person的update语句,数据库中personName被修改,不发出Card的update语句
        }
        //测试方法3
        public static void test3(Session session){
            Person person = (Person)session.get(Person.class, 1); //发出Person和Card的select语句
             Card card = person.getCard();
            System.out.println(person.getPersonName());
            System.out.println(card.getCardNumber());
            person.setPersonName("fancy");           //与初始值不一致
             card.setCardNumber("440911199008080808");//与初始值不一致
             session.save(person);    //同时发出Person和Card的update语句,数据库中的数据相应被修改
           //session.save(card);     //同时发出Person和Card的update语句,数据库中的数据相应被修改
        }
    }

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转载自：http://www.cnblogs.com/fancyzero/archive/2012/06/10/hibernate-one-to-one-annotation.html

[copycode.gif]: /images/20220720/c987bfd91c6744e39db4a30bdda95ef5.png