package com.deuask.one2many;
import java.util.HashSet;
import java.util.Set;
public class Deptment {
    private Integer id;
    private String deptname;
    private Set<Employ> employs=new HashSet<Employ>();
    public Integer getId() {
        return id;
    }
    public void setId(Integer id) {
        this.id = id;
    }
    public String getDeptname() {
        return deptname;
    }
    public void setDeptname(String deptname) {
        this.deptname = deptname;
    }
    public Set<Employ> getEmploys() {
        return employs;
    }
    public void setEmploys(Set<Employ> employs) {
        this.employs = employs;
    }
    @Override
    public String toString() {
        return "[所在部门: id=" + id + ", name=" + deptname + "]";
    }
}
Deptment.java
package com.deuask.one2many;
public class Employ {
    private Integer id;
    private String name;
    private Deptment deptment;
    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;
    }
    public Deptment getDeptment() {
        return deptment;
    }
    public void setDeptment(Deptment deptment) {
        this.deptment = deptment;
    }
    @Override
    public String toString() {
        return "[员工: id=" + id + ", name=" + name + "]";
    }
}
Employ.java
package com.deuask.one2many;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.cfg.Configuration;
public class HibernateUtil {
    private static SessionFactory sessionFactory;
    static{
        //加载hibernate主配置文件
        Configuration confg=new Configuration();
        confg.configure("com/deuask/one2many/hibernate.cfg.xml");
        sessionFactory=confg.buildSessionFactory();
    }
    //创建session
    public static Session getSession(){
        return sessionFactory.openSession();
    }
}
HibernateUtil.java
package com.deuask.one2many;
import org.hibernate.Session;
import org.hibernate.Transaction;
import org.junit.Test;
public class TestApp {
    @Test
    public void testSave(){
        //构建对象
        Deptment dept=new Deptment();
        dept.setDeptname("研发2部");
        Employ emp1=new Employ();
        emp1.setName("张三2");
        Employ emp2=new Employ();
        emp2.setName("李四2");
        dept.getEmploys().add(emp1);
        dept.getEmploys().add(emp2);
        emp1.setDeptment(dept);
        emp2.setDeptment(dept);
        //得到session
        Session session=HibernateUtil.getSession();
        Transaction tr=session.beginTransaction();
        session.save(emp1);
        session.save(emp2);
        session.save(dept);
        tr.commit();
        session.close();
    }
    @Test
    public void getTest(){
        //通过部门查找到所有的员工
        Session session=HibernateUtil.getSession();
        Deptment deptment=(Deptment)session.get(Deptment.class, 1);
        System.out.println("部门:"+deptment.getId()+" "+deptment.getDeptname());
        System.out.println(deptment.getEmploys());
    }
    @Test
    public void getTest2(){
        //通过部门查找到所有的员工
        Session session=HibernateUtil.getSession();
        //先找到员工
        Employ emp=(Employ) session.get(Employ.class, 1);
        //通过员工找到部门
        Deptment dept=emp.getDeptment();
        System.out.println(emp.getId()+" "+emp.getName());
        System.out.println(dept);
    }
}
TestApp.java
<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC 
    "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
    "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">
<hibernate-mapping package="com.deuask.one2many">
    <class name="com.deuask.one2many.Deptment" table="deptment">
        <id name="id">
            <generator class="native"></generator>
        </id>
        <property name="deptname"></property>
        <set name="employs" >
            <key column="deptid"></key>
            <one-to-many class="com.deuask.one2many.Employ"/>
        </set>
    </class>
</hibernate-mapping>
Department.hbm.xml
<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC 
    "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
    "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">
<hibernate-mapping package="com.deuask.one2many">
    <class name="com.deuask.one2many.Employ" table="employ">
        <id name="id">
            <generator class="native"></generator>
        </id>
        <property name="name"></property>
        <many-to-one name="deptment" class="com.deuask.one2many.Deptment" column="deptid"></many-to-one>
    </class>
</hibernate-mapping>
Employee.hbm.xml
<!DOCTYPE hibernate-configuration PUBLIC
    "-//Hibernate/Hibernate Configuration DTD 3.0//EN"
    "http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd">
<hibernate-configuration>
    <session-factory name="foo">
        <property name="hibernate.dialect">org.hibernate.dialect.MySQLDialect</property>
        <property name="connection.url">jdbc:mysql:///hibernate_20120328</property>
        <property name="connection.driver_class">com.mysql.jdbc.Driver</property>
        <property name="connection.username">root</property>
        <property name="hibernate.connection.password">hyy</property>
        <property name="hibernate.show_sql">true</property>
        <property name="hibernate.format_sql">false</property>
        <!-- 
            create：先删除，再创建
            update：如果表不存在就创建，不一样就更新，一样就什么都不做。
            create-drop：初始化时创建表，SessionFactory执行close()时删除表。
            validate：验证表结构是否一致，如果不一致，就抛异常。
         -->
        <property name="hbm2ddl.auto">update</property>
        <!-- 
            设置默认的事务隔离级别：
            隔离级别        对应的整数表示
            READ UNCOMMITED    1
            READ COMMITED    2
            REPEATABLE READ    4
            SERIALIZEABLE    8
         -->
        <property name="connection.isolation">2</property>
        <!-- 导入映射文件 -->
        <mapping resource="com/deuask/one2many/Employee.hbm.xml"/>
        <mapping resource="com/deuask/one2many/Department.hbm.xml"/>
    </session-factory>
</hibernate-configuration>
hibernate.cfg.xml