Hibernate一对一数据关联(二)

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)
);

3.POJO类
TUser.java

package cn.blogjava.start;

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 cn.blogjava.start;

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;
    }

}

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">1234</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="cn/blogjava/start/TUser.hbm.xml" />
        <mapping resource="cn/blogjava/start/TGroup.hbm.xml" />
    </session-factory>
</hibernate-configuration>

TGroup.hbm.xml

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="cn.blogjava.start.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="cn.blogjava.start.TGroup"
                    column="GROUP_ID"
                    cascade="all"
                    unique="true"
         />
    </class>
</hibernate-mapping>

4.测试代码

package cn.blogjava.start;

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",就要先插入group信息

// tran = session.beginTransaction();

// session.save(group);

// session.flush();

// tran.commit();

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());

}

二.双向一对一关联
需要对TGroup.java和TGroup.hbm.xml文件作修改

1.在TGroup.java中增加一个TUser类和相应的getter、setter方法
TGroup.java

package cn.blogjava.start;

import java.io.Serializable;

public class TGroup implements Serializable {

    private Integer id;
    private String name;
    private TUser user;

    public TUser getUser() {
        return user;
    }
    public void setUser(TUser user) {
        this.user = user;
    }
    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;
    }

}

2.在TGroup.hbm.xml中增加one-to-one配置

<?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="cn.blogjava.start.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" />
        <one-to-one
                     name="user"
                     class="cn.blogjava.start.TUser"
                     property-ref="group"
                     />
    </class>
</hibernate-mapping>

这样就实现了双向关联。可以实现双向查询

package cn.blogjava.start;

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");

            tran = session.beginTransaction();
            //设置关联
            user.setGroup(group);

            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'";
        String hql2 = " from TGroup where name='admin'";
        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");

            List groupList = session.createQuery(hql2).list();
            TGroup group = (TGroup)groupList.get(0);
            System.out.println("group name is " + group.getName());
            System.out.println("group user is " + group.getUser().getName());
            Assert.assertEquals(group.getUser().getName(), "byf");
        } catch (Exception e) {
            e.printStackTrace();
            Assert.fail(e.getMessage());
        }
    }
}

posted on 2006-07-05 15:11 knowhow 阅读(440) 评论(0) 编辑收藏所属分类: ORM：Hibernate及其他

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