第九章Hibernate映射一对一关联关系

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本文介绍Hibernate中一对一关联关系的两种映射方式：共享主键关联和唯一外键关联。详细解析了每种方式的数据表设计、Java实体类定义及Hibernate XML映射文件配置，并提供了测试代码样例。

第九章Hibernate映射一对一关联关系

共享主键关联
唯一外键关联

1.两个关联表使用相同的主键值

数据准备：

-- Create table
create table USERS1
(
  USERNAME VARCHAR2(40),
  PASSWORD VARCHAR2(40),
  ID       NUMBER(8) not null
)

Profile表用于保存用户的其他信息。

-- Create table
create table PROFILE
(
  ID       NUMBER(8) not null,
  EMAIL    VARCHAR2(200),
  PHONE    VARCHAR2(20),
  MOBILE   VARCHAR2(20),
  ADDRESS  VARCHAR2(200),
  POSTCODE VARCHAR2(10)
)

其中，ID即是主键又是外键。因此称为共享主键。

User：

public class User implements java.io.Serializable {
	private static final long serialVersionUID = 1L;
	private Integer id;
	private String username;
	private String password;
	private Profile profile;

	public Profile getProfile() {
		return profile;
	}

	public void setProfile(Profile profile) {
		this.profile = profile;
	}

	public User() {
	}

	public Integer getId() {
		return this.id;
	}

	public void setId(Integer id) {
		this.id = id;
	}

	public String getUsername() {
		return this.username;
	}

	public void setUsername(String username) {
		this.username = username;
	}

	public String getPassword() {
		return this.password;
	}

	public void setPassword(String password) {
		this.password = password;
	}
}

User映射配置：

<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<!-- 
    Mapping file autogenerated by MyEclipse Persistence Tools
-->
<hibernate-mapping>
    <class name="com.crazy.User" table="USERS1" schema="SCOTT">
        <id name="id" type="java.lang.Integer">
            <column name="ID" precision="8" scale="0" />
            <generator class="increment"></generator>
        </id>
        <property name="username" type="java.lang.String">
            <column name="USERNAME" length="40" />
        </property>
        <property name="password" type="java.lang.String">
            <column name="PASSWORD" length="40" />
        </property>
        <one-to-one name="profile" class="com.crazy.Profile"></one-to-one>
    </class>
</hibernate-mapping>

Profile类：

public class Profile implements java.io.Serializable {
	private Integer id;
	private String email;
	private String phone;
	private String mobile;
	private String address;
	private String postcode;
	private User user;

	public Profile() {
	}

	public Integer getId() {
		return this.id;
	}

	public void setId(Integer id) {
		this.id = id;
	}

	public User getUser() {
		return user;
	}

	public void setUser(User user) {
		this.user = user;
	}

	public String getEmail() {
		return this.email;
	}

	public void setEmail(String email) {
		this.email = email;
	}

	public String getPhone() {
		return this.phone;
	}

	public void setPhone(String phone) {
		this.phone = phone;
	}

	public String getMobile() {
		return this.mobile;
	}

	public void setMobile(String mobile) {
		this.mobile = mobile;
	}

	public String getAddress() {
		return this.address;
	}

	public void setAddress(String address) {
		this.address = address;
	}

	public String getPostcode() {
		return this.postcode;
	}

	public void setPostcode(String postcode) {
		this.postcode = postcode;
	}
}

Profile映射配置：

其主键是使用user的。

<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<!-- 
    Mapping file autogenerated by MyEclipse Persistence Tools
-->
<hibernate-mapping>
    <class name="com.crazy.Profile" table="PROFILE" schema="SCOTT">
        <id name="id" type="java.lang.Integer">
            <column name="ID" precision="8" scale="0" />
            <generator class="foreign">
            	<param name="property">user</param>
            </generator>
        </id>
        <property name="email" type="java.lang.String">
            <column name="EMAIL" length="200" />
        </property>
        <property name="phone" type="java.lang.String">
            <column name="PHONE" length="20" />
        </property>
        <property name="mobile" type="java.lang.String">
            <column name="MOBILE" length="20" />
        </property>
        <property name="address" type="java.lang.String">
            <column name="ADDRESS" length="200" />
        </property>
        <property name="postcode" type="java.lang.String">
            <column name="POSTCODE" length="10" />
        </property>
        <one-to-one name="user" class="com.crazy.User"></one-to-one>
    </class>
</hibernate-mapping>

测试代码：

public class HibernateTest {

	public static void main(String args[]){
		HibernateTest test = new HibernateTest();
		test.add();
	}
	
	public void add(){
		Profile profile = new Profile();
		profile.setAddress("河南胜利路");
		profile.setEmail("yesmeshtu2008@163.com");
		profile.setMobile("13301239472145");
		User user = new User();
		profile.setUser(user);
		user.setUsername("grass");
		user.setPassword("123");
		user.setProfile(profile);
		Session session = new Configuration().configure().buildSessionFactory().openSession();
		session.beginTransaction();
		session.save(profile);
		session.save(user);
		session.getTransaction().commit();
	}
}

2.多对一关联的特殊形式，要求多方唯一

User类：

public class User  implements java.io.Serializable {
     private Integer id;
     private String username;
     private String password;
     private Profile profile;
     
    public Profile getProfile() {
		return profile;
	}

	public void setProfile(Profile profile) {
		this.profile = profile;
	}

	public User() {
    }
    
    public Integer getId() {
        return this.id;
    }
    
    public void setId(Integer id) {
        this.id = id;
    }

    public String getUsername() {
        return this.username;
    }
    
    public void setUsername(String username) {
        this.username = username;
    }

    public String getPassword() {
        return this.password;
    }
    
    public void setPassword(String password) {
        this.password = password;
    }
}

User映射配置：

<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<!-- 
    Mapping file autogenerated by MyEclipse Persistence Tools
-->
<hibernate-mapping>
    <class name="com.crazy.User" table="USERS1" schema="SCOTT">
        <id name="id" type="java.lang.Integer">
            <column name="ID" precision="8" scale="0" />
            <generator class="increment" />
        </id>
        <property name="username" type="java.lang.String">
            <column name="USERNAME" length="40" />
        </property>
        <property name="password" type="java.lang.String">
            <column name="PASSWORD" length="40" />
        </property>
        <one-to-one name="profile" class="com.crazy.Profile"></one-to-one>
    </class>
</hibernate-mapping>

Profile类：

public class Profile  implements java.io.Serializable {
     private Integer id;
     private String email;
     private String phone;
     private String mobile;
     private String address;
     private String postcode;
     private User user;

    public User getUser() {
		return user;
	}

	public void setUser(User user) {
		this.user = user;
	}

	public Profile() {
    }

    public Integer getId() {
        return this.id;
    }
    
    public void setId(Integer id) {
        this.id = id;
    }

    public String getEmail() {
        return this.email;
    }
    
    public void setEmail(String email) {
        this.email = email;
    }

    public String getPhone() {
        return this.phone;
    }
    
    public void setPhone(String phone) {
        this.phone = phone;
    }

    public String getMobile() {
        return this.mobile;
    }
    
    public void setMobile(String mobile) {
        this.mobile = mobile;
    }

    public String getAddress() {
        return this.address;
    }
    
    public void setAddress(String address) {
        this.address = address;
    }

    public String getPostcode() {
        return this.postcode;
    }
    
    public void setPostcode(String postcode) {
        this.postcode = postcode;
    }
}

Profile映射配置：

<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<!-- 
    Mapping file autogenerated by MyEclipse Persistence Tools
-->
<hibernate-mapping>
    <class name="com.crazy.Profile" table="PROFILE1" schema="SCOTT">
        <id name="id" type="java.lang.Integer">
            <column name="ID" precision="8" scale="0" />
            <generator class="increment" />
        </id>
        <property name="email" type="java.lang.String">
            <column name="EMAIL" length="200" />
        </property>
        <property name="phone" type="java.lang.String">
            <column name="PHONE" length="20" />
        </property>
        <property name="mobile" type="java.lang.String">
            <column name="MOBILE" length="20" />
        </property>
        <property name="address" type="java.lang.String">
            <column name="ADDRESS" length="200" />
        </property>
        <property name="postcode" type="java.lang.String">
            <column name="POSTCODE" length="10" />
        </property>
        <many-to-one name="user" class="com.crazy.User" unique="true">
        	<column name="user_id"></column>
        </many-to-one>
    </class>
</hibernate-mapping>

配置如下：

  <many-to-one name="user" class="com.crazy.User" unique="true">
        	<column name="user_id"></column>
        </many-to-one>

测试代码:

public class HibernateTest {

	public static void main(String args[]){
		HibernateTest test = new HibernateTest();
		test.add();
	}
	
	public void add(){
		Profile profile = new Profile();
		profile.setAddress("河南胜利路");
		profile.setEmail("yesmeshtu2008@163.com");
		profile.setMobile("13309472145");
		User user = new User();
		profile.setUser(user);
		user.setUsername("grass");
		user.setPassword("123");
		user.setProfile(profile);
		Session session = new Configuration().configure().buildSessionFactory().openSession();
		session.beginTransaction();
		session.save(profile);
		session.save(user);
		
		session.getTransaction().commit();
	}
}