第一节：Hibernate 一对一映射关系实现
假设一个用户对应一个地址；
1）按照主键映射：
User.java:
package com.cy.model;
public class User {
private int id;
private String name;
private Address address;
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;
}
public Address getAddress() {
return address;
}
public void setAddress(Address address) {
this.address = address;
}
}
Address.java:
package com.cy.model;
public class Address {
private int id;
private String address;
private String zipcode;
private User user;
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getAddress() {
return address;
}
public void setAddress(String address) {
this.address = address;
}
public String getZipcode() {
return zipcode;
}
public void setZipcode(String zipcode) {
this.zipcode = zipcode;
}
public User getUser() {
return user;
}
public void setUser(User user) {
this.user = user;
}
}
User.hbm.xml:
<hibernate-mapping package="com.cy.model">
<class name="User" table="t_user">
<id name="id" column="userId">
<generator class="native"></generator>
</id>
<property name="name" column="userName"></property>
<one-to-one name="address" class="com.cy.model.Address" cascade="all"></one-to-one>
</class>
</hibernate-mapping>
Address.hbm.xml:
<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
"-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd"> <hibernate-mapping package="com.cy.model"> <!--
t_address表的主键和t_user表的主键一样；
t_address表的id既做主键，又做外键。
-->
<class name="Address" table="t_address">
<id name="id" column="addressId">
<generator class="foreign">
<param name="property">user</param>
</generator>
</id>
<property name="address" column="address"></property>
<property name="zipcode" column="zipcode"></property> <!-- 配置constrained="true"让t_address和t_user共享主键 -->
<one-to-one name="user" class="com.cy.model.User" constrained="true"></one-to-one>
</class> </hibernate-mapping>
测试代码：
@Test
public void testSave1(){
User user=new User();
user.setName("张三"); Address address=new Address();
address.setAddress("昭潭镇");
address.setZipcode("247280");
address.setUser(user); user.setAddress(address);
session.save(user);
}
结果：
t_address表结构：
t_address表的addressId既是主键，又是外键；
执行结果，查看数据库：
2）按照外键映射
User2.java：
package com.cy.model;
public class User2 {
private int id;
private String name;
private Address2 address;
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;
}
public Address2 getAddress() {
return address;
}
public void setAddress(Address2 address) {
this.address = address;
}
}
Address2.java:
package com.cy.model;
public class Address2 {
private int id;
private String address;
private String zipcode;
private User2 user;
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getAddress() {
return address;
}
public void setAddress(String address) {
this.address = address;
}
public String getZipcode() {
return zipcode;
}
public void setZipcode(String zipcode) {
this.zipcode = zipcode;
}
public User2 getUser() {
return user;
}
public void setUser(User2 user) {
this.user = user;
}
}
User2.hbm.xml:
<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
"-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd"> <hibernate-mapping package="com.cy.model"> <class name="User2" table="t_user2">
<id name="id" column="userId">
<generator class="native"></generator>
</id>
<property name="name" column="userName"></property> <!--
unique="true" 不能重复，唯一的；
外键本来是可以重复的，但是通过unique="true"实现了唯一，这样就实现了一对一
-->
<many-to-one name="address" class="com.cy.model.Address2" column="addressId" cascade="all" unique="true"></many-to-one>
</class> </hibernate-mapping>
Address2.hbm.xml:
<hibernate-mapping package="com.cy.model">
<class name="Address2" table="t_address2">
<id name="id" column="addressId">
<generator class="native"></generator>
</id>
<property name="address" column="address"></property>
<property name="zipcode" column="zipcode"></property> <one-to-one name="user" class="com.cy.model.User2" property-ref="address"></one-to-one>
</class> </hibernate-mapping>
测试代码：
@Test
public void testSave2(){
User2 user=new User2();
user.setName("李四"); Address2 address=new Address2();
address.setAddress("东至县昭潭镇");
address.setZipcode("247280");
address.setUser(user); user.setAddress(address);
session.save(user);
}
查看生辰的表：
t_user2表结构：
t_user2的外键addressId关联t_address2的主键；并且addressId存在唯一约束；
数据库中记录：
