Hibernate学习札记(对象-一对一关系映射)

Hibernate学习笔记(对象-一对一关系映射)

话不多说，直接上例子,

Husband和Wife之间的一对一关联关系:

Husband持久化类代码:

public class User {
 private Integer h_id;
 private String husbandName;
 private Wife wife;

 public Integer getH_id() {
  return h_id;
 }

 public void setU_id(Integer h_id) {
  this.h_id = h_id;
 }

 public Wife getWife() {
  return wife;
 }

 public void setWife(Wife wife) {
  this.wife = wife;
 }

 public void setU_id(Integer u_id) {
  this.u_id = u_id;
 }

 public String getHusbandName() {
  return husbandName;
 }

}

Wife持久化类:

public class Wife {
	private String wifeName;
	private Husband husband;
	private Integer w_id;

	public Integer getW_id() {
		return w_id;
	}

	public void setW_id(Integer w_id) {
		this.w_id = w_id;
	}

	public String getWifeName() {
		return wifeName;
	}

	public void setWifeName(String wifeName) {
		this.wifeName = wifeName;
	}

	public User getHusband() {
		return usband;
	}

	public void setHusband(Husband husband) {
		this.husband = husband;
	}

}

一对一关系的配置存在两种方式，一种是通过主键，另外一种是通过唯一外键去关联

配置文件如下:

<hibernate-mapping package="com.lovo">
	<class name="Husband" table="t_husband">
		<id name="u_id" column="f_user_id" type="integer">
			<generator class="identity"></generator>
		</id>
		<property name="husbandName" type="string" column="f_husbandName"></property>
<!-- 基于主键的一对一-->
<!-- 这里就是一对一的映射 -->
		<one-to-one name="wife" cascade="save-update"></one-to-one>

<!--唯一外键关联的一对一-->

<!--这里我是把huband作为多的一方，column t_husband表中的字段名，表示一个外键-->

<!--设置unique="true"表示唯一性-->

<many-to-one name="wife"
   class="Wife"
   column="fk_wife_id"
   cascade="save-update"
   unique="true">
   </many-to-one>

Wife类映射文件的配置：

	<class name="Wife" table="t_wife">
		<!-- 基于主键的一对一关系 -->
		<id column="f_wife_id" name="w_id" type="integer">
			<!-- 注意: -->
			<!-- 本类的id 既是主键,又是外键  -->
			<!-- Wife对象的是从对象, huband是主对象, 先有主,后有从.  -->
			<!-- 此处的husband是Wife类的一个属性 -->
			<generator class="foreign">
				<param name="property">user</param>
			</generator>
		</id>
		<property name="wifeName" type="string" column="f_wifeName">
		</property>
		<!-- 此处的user是User类的一个属性 -->
		<!-- constrained="true" 对生成的数据表产生约束,t_wife表的w_id既是主键,又是外键 -->
		<!-- constrained="false" 表结构上没有约束, 取何值对对象关系没影响,只是对表结构有影响-->
		<one-to-one name="husband" constrained="true" cascade="save-update">
		</one-to-one>
</class>

<!--基于外键的一对一-->
   <one-to-one name="husband" class="Husband" property-ref="wife" cascade="save-update">
   </one-to-one>

测试就没写了，参照一对多关系中的例子。

Hibernate学习札记(对象-一对一关系映射)

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