hibernate--一对一单（双）向外键关联

客官°小女子只卖身不卖艺 2024-02-18 14:47 41阅读 0赞

1、annotation进行注解：

实体类Husband.java：

package com.bean;
    
    import javax.persistence.Entity;
    import javax.persistence.GeneratedValue;
    import javax.persistence.Id;
    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 void setId(int id) {
    		this.id = id;
    	}
    
    	public String getName() {
    		return name;
    	}
    
    	public void setName(String name) {
    		this.name = name;
    	}
    
    	@OneToOne
    	public Wife getWife() {
    		return wife;
    	}
    
    	public void setWife(Wife wife) {
    		this.wife = wife;
    	}
    
    }

Wife.java:

package com.bean;
    
    import javax.persistence.Entity;
    import javax.persistence.Id;
    
    @Entity
    public class Wife {
    	private int id;
    	private String name;
    
    	@Id
    	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;
    	}
    
    }

cfg.xml配置：

<?xml version="1.0" encoding="UTF-8"?>
    <!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="connection.driver_class">com.mysql.jdbc.Driver</property>    
         <property name="connection.url">jdbc:mysql://localhost:3306/user</property>     
         <property name="connection.username">root</property>   
         <property name="connection.password">root</property>
         
         <property name="dialect">org.hibernate.dialect.MySQLDialect</property>
         <property name="show_sql">true</property>
         
         <property name="hbm2ddl.auto">update</property>
         <property name="show_sql">true</property>
         <property name="format_sql">true</property>  
         
         <property name="current_session_context_class">thread</property>
         <mapping class="com.bean.Husband"/>
         <mapping class="com.bean.Wife"/>
       </session-factory>
    </hibernate-configuration>

2、通过XML进行配置：(一对一) 通过唯一性约束完成

Husband.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.bean.Husband" table = "Husband" >
    
         <id name = "id" column="id">
           <generator class="native"/>
         </id>
    
         <property name="name" />
         <many-to-one name="wife" unique="true" class="com.bean.Husband" column="wife_id"/>
      </class>
    </hibernate-mapping>

Wife.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.bean.Wife" table = "Wife" >
    
         <id name = "id" column="wife_id">
           <generator class="native"/>
         </id>
    
         <property name="name" />
      </class>
    </hibernate-mapping>

cfg.xml中映射：

一对一双向外键关联：

XML配置参考帮助文档，<one-to-one property-ref>

annotation注解：

修改person类即可：

@Entity
    public class Person {
    	private int id;
    	private String name;
    	private PersonID personID;
    
    	@OneToOne(mappedBy="person")
    	public PersonID getPersonID() {
    		return personID;
    	}

对于双向外键关联，一定得注解@OneToOne(mappedBy="person") ，因为数据库中单向即可！