多对一

datasource配置文件：

hibernate.cfg.hbm:

 

<!DOCTYPE hibernate-configuration PUBLIC
 "-//Hibernate/Hibernate Configuration DTD 3.0//EN"
 "http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">

<hibernate-configuration>
 <session-factory name="jnty">
  <property name="hibernate.connection.url">jdbc:mysql://127.0.0.1/hibernate</property>
  <property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property>
  <property name="hibernate.connection.username">root</property>
  <property name="hibernate.connection.password">root</property>
        <property name="dialect">org.hibernate.dialect.MySQLDialect</property>
        <property name="hibernate.show_sql">true</property>
       
        <mapping resource="com/jnty/bean/User.hbm.xml"/>
        <mapping resource="com/jnty/bean/Group.hbm.xml"/>
 </session-factory>
</hibernate-configuration>

 

Group.java

package com.jnty.bean;

public class Group {
 
 private int id;
 
 private String name;

 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;
 }
}

<?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.jnty.bean.Group" table="t_group">
  <id name="id">
   <generator class="native"/>
  </id>
  <property name="name"/>
 </class>
</hibernate-mapping>

 

package com.jnty.bean;

import java.util.Date;

public class User {

 private int id;
 
 private String name;
 
 private String password;
 
 private Date createTime;
 
 private Date expireTime;
 
 private Group group;

 public Group getGroup() {
  return group;
 }

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

 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 String getPassword() {
  return password;
 }

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

 public Date getCreateTime() {
  return createTime;
 }

 public void setCreateTime(Date createTime) {
  this.createTime = createTime;
 }

 public Date getExpireTime() {
  return expireTime;
 }

 public void setExpireTime(Date expireTime) {
  this.expireTime = expireTime;
 }
 
 
}

<?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.jnty.bean.User" table="t_user">
  <id name="id">
   <!-- 主键生成策略 -->
   <generator class="native"/>
  </id>
  <property name="name" column="name"/>
  <property name="password"/>
  <property name="createTime"/>
  <property name="expireTime"/>
  <many-to-one name="group" column="group_id" cascade="all" />
 </class>
</hibernate-mapping>

 

 

生成表：

package com.jnty.util;

import org.hibernate.cfg.Configuration;
import org.hibernate.tool.hbm2ddl.SchemaExport;

public class GenarateTable {
 
 public static void main(String args[]){
//  Configuration cfg = new Configuration();//读取默认的properties文件
  //读取hibernate.cfg.xml
  Configuration cfg = new Configuration().configure();
  SchemaExport export = new SchemaExport(cfg);
  export.create(true, true);
 }
}

基本工具类：

package com.jnty.util;

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

public class HibernateUtils {

 private static SessionFactory factory;
 
 static {
  try {
   Configuration cfg = new Configuration().configure();
   factory = cfg.buildSessionFactory();
  }catch(Exception e) {
   e.printStackTrace();
  }
 }
 
 public static SessionFactory getSessionFactory() {
  return factory;
 }
 
 public static Session getSession() {
  return factory.openSession();
 }
 
 public static void closeSession(Session session) {
  if (session != null) {
   if (session.isOpen()) {
    session.close();
   }
  }
 }
}

测试例子：

package com.jnty;

import java.util.Date;

import junit.framework.TestCase;

import org.hibernate.Session;

import com.jnty.bean.Group;
import com.jnty.bean.User;
import com.jnty.util.HibernateUtils;

public class Many2OneTest extends TestCase {

 public void testSave1() {
  Session session = null;
  try {
   session = HibernateUtils.getSession();
   session.beginTransaction();
   
   Group group = new Group();
   group.setName("江南科技");
   
   //单独保存user也是可以的,group_id字段就为null
   User user1 = new User();
   user1.setName("��江南");
   user1.setPassword("www");
   user1.setCreateTime(new Date());
   user1.setExpireTime(new Date());
   user1.setGroup(group);
   
   session.save(user1);
   session.getTransaction().commit();
  }catch(Exception e) {
   e.printStackTrace();
   session.getTransaction().rollback();
  }finally {
   HibernateUtils.closeSession(session);
  }
 } 
 
 
 
 public void testLoad1() {
  Session session = null;
  try {
   session = HibernateUtils.getSession();
   session.beginTransaction();
   User user = (User)session.load(User.class, 1);
   System.out.println("user.name=" + user.getName());
   System.out.println("user.group.name=" + user.getGroup().getName());
   
   session.getTransaction().commit();
  }catch(Exception e) {
   e.printStackTrace();
   session.getTransaction().rollback();
  }finally {
   HibernateUtils.closeSession(session);
  }
 } 
 
}