一对一

一对一单向

定义两个类,两个映射文件一个工具类生成表

public class Group {
	
	private int id;	
	private String name;
                //这里省略setter，getter方法
}

 

public class User{
     private int id;
     private String name;
     private Group group;
      //这里省略setter，getter方法
}

 

	<class name="many2one.User" table="t_user">
		<id name="id">
			<generator class="native"/>
		</id>
		<property name="name"/>	
		<!-- 无连接表 -->	
		 <many-to-one name="group" column="groupid" unique="true" not-null="true"/>
		 <!-- 有连接表 
		<join table="User_Group" optional="true">
			<key column="userid" unique="true"/>
			<many-to-one name="group" class="many2one.Group" column="groupid" unique="true" not-null="true" />			
		</join>	 -->
	</class>

 

	<class name="many2one.Group" table="t_group">
		<id name="id">
			<generator class="native"/>
		</id>
		<property name="name"/>
	</class>

 

	public static void main(String[] args) {
		//读取hibernate.cfg.xml文件
		Configuration cfg = new Configuration().configure();
		SchemaExport export = new SchemaExport(cfg);
		export.create(true, true);
	}

 一对一双向

在原来的基础上，添加如下的两个配置

private User user;

 

<!-- 一对多双向 -->
<one-to-one name="user" property-ref="group" />

 

基于主键的一对一

两个实体类，两个映射文件

public class Person {
	
	private int id;
	private Address address;
                //setter,getter
}

 

public class Address {
	
	private int id;
	private Person person;
                //setter,getter方法
}

 

	<class name="Person" table="Person">	
		<id name="id" column="personId">            
            <generator class="native" />
        </id>
		<one-to-one name="address" />		
	</class>

 

	<class name="Address" table="Address">	
		<id name="id" column="personId">       
            <generator class="foreign">
            	<param name="property">person</param>
            </generator>
        </id>
		<one-to-one name="person" constrained="true" />	
	</class>