Hibernate一对一数据关联：唯一外键关联
一.单向一对一关联
1.数据模型如下图所示：


2.数据表sql
DROP TABLE T_User;
DROP TABLE T_Group;

CREATE TABLE T_Group (
       id INT NOT NULL AUTO_INCREMENT
     , name VARCHAR(50)
     , PRIMARY KEY (id)
);

CREATE TABLE T_User (
       id INT NOT NULL AUTO_INCREMENT
     , name VARCHAR(50)
     , age INT
     , group_id INT NOT NULL
     , PRIMARY KEY (id)
     , INDEX (group_id)
     , CONSTRAINT FK_T_User_1 FOREIGN KEY (group_id)
                  REFERENCES T_Group (id)
);

</DIV>
3.POJO类
TUser.java
package com.jeff.wap.bo;

public class TUser  implements java.io.Serializable {
    // Fields    
     private Integer id;
     private Integer age;
     private String name;
     private TGroup group;


    // Constructors

    public Integer getAge() {
        return age;
    }

    public void setAge(Integer age) {
        this.age = age;
    }


    public TGroup getGroup() {
        return group;
    }

    public void setGroup(TGroup group) {
        this.group = group;
    }

    /** default constructor */
    public TUser() {
    }
    
    /** constructor with id */
    public TUser(Integer id) {
        this.id = id;
    }

    // Property accessors

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

    public String getName() {
        return this.name;
    }
    
    public void setName(String name) {
        this.name = name;
    }
}
TGroup.java
package com.jeff.wap.bo;

import java.io.Serializable;

public class TGroup implements Serializable {
    
    private Integer id;
    private String name;
    
    public Integer getId() {
        return id;
    }
    public void setId(Integer id) {
        this.id = id;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    
}
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3.配置文件
hibernate.cfg.xml
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-configuration PUBLIC
        "-//Hibernate/Hibernate Configuration DTD 3.0//EN"
        "http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">
<hibernate-configuration>
    <session-factory>
        <property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property>
        <property name="hibernate.connection.password">pwd</property>
        <property name="hibernate.connection.url">jdbc:mysql://localhost:3306/sample</property>
        <property name="hibernate.connection.username">root</property>
        <property name="hibernate.dialect">org.hibernate.dialect.MySQLDialect</property>
        <mapping resource="com/jeff/wap/bo/TUser.hbm.xml" />
        <mapping resource="com/jeff/wap/bo/TGroup.hbm.xml" />        
    </session-factory>
</hibernate-configuration>
</DIV>
TGroup.hbm.xml
<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping>
    <class name="com.jeff.wap.bo.TGroup" table="T_Group" catalog="sample">
        <id name="id" type="integer">
            <column name="id" />
            <generator class="native" />
        </id>
        <property name="name" type="string" column="name" />
    </class>
</hibernate-mapping>
</DIV>
TUser.hbm.xml
<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping>
    <class name="com.jeff.wap.bo.TUser" table="T_User" catalog="sample">
        <id name="id" type="integer">
            <column name="id" />
            <generator class="native" />
        </id>
        <property name="name" type="string">
            <column name="name" length="100" not-null="true" />
        </property>
        <property name="age" type="java.lang.Integer" column="age" />
        <many-to-one name="group" 
                    class="com.jeff.wap.bo.TGroup" 
                    column="group_id"
                    cascade="all"
                    unique="true" 
         />
    </class>
</hibernate-mapping>
</DIV>
4.测试代码
package com.jeff.wap.bo;

import java.util.List;

import junit.framework.Assert;
import junit.framework.TestCase;

import org.hibernate.HibernateException;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.cfg.Configuration;


public class HibernateTest extends TestCase {
    
    Session session = null;

    protected void setUp() {
        try {
            Configuration config = new Configuration().configure();
            SessionFactory sessionFactory = config.buildSessionFactory();
            session = sessionFactory.openSession();
            
        } catch (HibernateException e) {
            e.printStackTrace();
        }        
    }

    protected void tearDown() {
        try {
            session.close();        
        } catch (HibernateException e) {
            e.printStackTrace();
        }        
    }    
    
    /**
     * 对象持久化测试(Insert方法)
     */        
    public void testInsert() {
        Transaction tran = null;
        try {
        
            TUser user = new TUser();
            user.setName("byf");
            user.setAge(new Integer(26));
            
            TGroup group = new TGroup();
            group.setName("Admin");
            
               // 如果在配置文件中没有cascade="all",测试就会报错
  
            tran = session.beginTransaction();                    
            //设置关联
            user.setGroup(group);

               //插入user信息
            session.save(user);
            session.flush();
            tran.commit();
            Assert.assertEquals(user.getId().intValue()>0 ,true);
        } catch (HibernateException e) {
            e.printStackTrace();
            Assert.fail(e.getMessage());
            if(tran != null) {
                try {
                    tran.rollback();
                } catch (Exception e1) {
                    e1.printStackTrace();
                }
            }
        }
    }
    
    /**
     * 对象读取测试(Select方法)
     */            
    public void testSelect(){
        String hql = " from TUser where name='byf'";
        try {
            List userList = session.createQuery(hql).list();
            TUser user = (TUser)userList.get(0);
            System.out.println("user name is " + user.getName());
            System.out.println("user group is " + user.getGroup().getName());
            Assert.assertEquals(user.getName(), "byf");
        } catch (Exception e) {
            e.printStackTrace();
            Assert.fail(e.getMessage());
        }
    }
}
 

本文来源：http://blog.csdn.net/alexjjf/archive/2007/07/06/1681056.aspx