关联映射（多对一单向外键）

关联映射（多对一单向外键）

映射文件：<many-to-one name=”depart” column=”depart_id” />

 

 hibernate.cfg.xml

<mapping resource="org/kevin/domain/Department.hbm.xml" />
<mapping resource="org/kevin/domain/Employee.hbm.xml" />

Department.java

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

    public Department() {

    }

    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;
    }
}

Employee.java

public class Employee {
    private int id;
    private String name;
    private Department depart;
    
    public Employee(){}

    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 Department getDepart() {
        return depart;
    }

    public void setDepart(Department depart) {
        this.depart = depart;
    }    
}

Department.hbm.xml

<hibernate-mapping>
    <class name="org.kevin.domain.Department">
        <id name="id">
            <generator class="native"></generator>
        </id>
        
        <property name="name"></property>
    </class>
</hibernate-mapping>

Employee.hbm.xml

<hibernate-mapping>
    <class name="org.kevin.domain.Employee">
        <id name="id">
            <generator class="native"></generator>
        </id>
        
        <property name="name"></property>
        <many-to-one name="depart" column="depart_id" />
    </class>    
</hibernate-mapping>

HibernateUtil.java

package org.kevin.util;

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

public final class HibernateUitl {
    private static SessionFactory sessionFactory;

    private HibernateUitl() {
    }

    static {
        Configuration cfg = new Configuration();
        cfg.configure();
        sessionFactory = cfg.buildSessionFactory();
    }

    public static SessionFactory getSessionFactory() {
        return sessionFactory;
    }

    public static Session getSession() {
        return sessionFactory.openSession();
    }
}

TestManyToOne.java
新建Source Folder  test 
新建包和src 实体类相同的包路径 

@Test
    public void addTest(){
        Department dep = new Department();
        dep.setName("depart name");
        
        Employee emp = new Employee();
        emp.setName("emp name");
        emp.setDepart(dep);
        
        Session s = null;
        Transaction tx = null;
        try {
            s = HibernateUitl.getSession();
            tx = s.beginTransaction();
            s.save(dep);
            s.save(emp);
            tx.commit();
        } catch (HibernateException e) {
            e.printStackTrace();
        }finally{
            if(s!=null)
                s.close();
        }            
    }

@Test
    public void getTest(){
        int empId=1;
        Session s = null;
        try {
            s = HibernateUitl.getSession();
            Employee e = (Employee) s.get(Employee.class, empId);
            //System.out.println( e.getName() );
            System.out.println( e.getDepart().getName() ); 
        } finally {
            if (s != null)
                s.close();
        }
    }

 

create table Department (id integer not null auto_increment, name varchar(255), primary key (id))
create table Employee (id integer not null auto_increment, name varchar(255), depart_id integer, primary key (id))
alter table Employee add index FK4AFD4ACE275992EB (depart_id), add constraint FK4AFD4ACE275992EB foreign key (depart_id) references Department (id)
10:02:50,092 INFO SchemaUpdate:217 - schema update complete
Hibernate:
insert
into
Department
(name)
values
(?)
Hibernate:
insert
into
Employee
(name, depart_id)
values
(?, ?)