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">
   
   <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);
  }
}

}

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