Hibernate中，One2One的基于注解Annotation的实现

悠悠 2022-09-24 00:24 93阅读 0赞

1、在Hibernate中，One2One的基于注解Annotation的实现

2、Student.java的代码（带注解，**注意注解是在哪个包下的**）

import javax.persistence.Entity;
    @Entity
    @Table(name = "student")
    public class Student {
    	@Id
    	@GeneratedValue
    	private int id;
    	@Column(name = "age")
    	private int age;
    	private String name;
    
    	// one2one，持有IdCard
    	@OneToOne(cascade = CascadeType.ALL)
    	@JoinColumn(name = "idcard")
    	private IdCard idCard;
    
    	public Student() {
    	}
    
    	public int getId() {
    		return id;
    	}
    
    	public void setId(int id) {
    		this.id = id;
    	}
    
    	public int getAge() {
    		return age;
    	}
    
    	public void setAge(int age) {
    		this.age = age;
    	}
    
    	public String getName() {
    		return name;
    	}
    
    	public void setName(String name) {
    		this.name = name;
    	}
    
    	public IdCard getIdCard() {
    		return idCard;
    	}
    
    	public void setIdCard(IdCard idCard) {
    		this.idCard = idCard;
    	}
    
    	@Override
    	public String toString() {
    		return "Student [id=" + id + ", age=" + age + ", name=" + name + "]";
    	}
    
    }

3、IdCard.java的代码（带注解，**注意注解是在哪个包下的**）

import javax.persistence.Table;
    
    @Entity
    @Table(name = "idcard")
    public class IdCard {
    	@Id
    	@GeneratedValue
    	private int id;
    	@Column(name = "idcardnumber")
    	private String idcardnumber;
    
    	public IdCard() {
    	}
    
    	public int getId() {
    		return id;
    	}
    
    	public void setId(int id) {
    		this.id = id;
    	}
    
    	public String getIdcardnumber() {
    		return idcardnumber;
    	}
    
    	public void setIdcardnumber(String idcardnumber) {
    		this.idcardnumber = idcardnumber;
    	}
    
    	@Override
    	public String toString() {
    		return "IdCard [id=" + id + ", idcardnumber=" + idcardnumber + "]";
    	}
    
    }

4、hibernate.cfg.xml的配置

4.1 将Student.java和ClassRoom.java，加入到hibernate.cfg.xml的配置文件里面

<mapping class="com.hibernate.entity.IdCard" />
    	<mapping class="com.hibernate.entity.Student" />

4.2  hibernate.cfg.xml的配置的完整内容

<!DOCTYPE hibernate-configuration PUBLIC
    	"-//Hibernate/Hibernate Configuration DTD 3.0//EN"
    	"http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd">
    
    <hibernate-configuration>
    	
    <session-factory>
    
    	
    	<property name="hibernate.connection.driver_class">
    		com.mysql.jdbc.Driver
    	</property>
    	<property name="hibernate.connection.url">
    		jdbc:mysql:///hibernate
    	</property>
    	<property name="hibernate.connection.username">root</property>
    	<property name="hibernate.connection.password">1234</property>
    	
    	<property name="hibernate.dialect">
    		org.hibernate.dialect.MySQL5Dialect
    	</property>
    
    
    	
    	
    	<property name="hibernate.show_sql">true</property>
    	
    	<property name="hibernate.format_sql">true</property>
    	
    	<property name="hibernate.hbm2ddl.auto">update</property>
    
    	
    	<mapping class="com.hibernate.entity.IdCard" />
    	<mapping class="com.hibernate.entity.Student" />
    </session-factory>
    </hibernate-configuration>

5、测试代码

public class HibernateTest {
    
    	@Test
    	public void testone2many() {
    
    		Student stu1 = new Student();
    		stu1.setAge(18);
    		stu1.setName("18");
    
    		Student stu2 = new Student();
    		stu2.setAge(19);
    		stu2.setName("19");
    
    		IdCard idCard = new IdCard();
    		idCard.setIdcardnumber("1234567");
    		// 保存到数据库
    		IClassRoomDao roomDao = new ClassRoomDaoImpl();
    		IStudentDao studentDao = new StudentDaoImpl();
    
    		// 注册关系
    		stu1.setIdCard(idCard);
    		stu2.setIdCard(idCard);
    		// 在保存一的一方
    		roomDao.add(idCard);
    
    		// 先保存多的一方
    		studentDao.add(stu1);
    		studentDao.add(stu2);
    	}
    
    }

6、代码下载

[代码下载][Link 1]

[Link 1]: http://pan.baidu.com/s/1b2hmn8