Hibernate 多对一小案例

最新推荐文章于 2019-09-18 21:40:50 发布

原创最新推荐文章于 2019-09-18 21:40:50 发布 · 275 阅读

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CC 4.0 BY-SA版权

本文介绍使用Hibernate实现多对一关系映射的方法，包括实体类定义、映射文件配置及测试类编写等关键步骤。

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1.创建实体类Dept和Emp以及小配置

package cn.happy.manytoone;

/**
 * Created by guo on 2017/10/6.
 */
public class Dept {
    private int deptno;
    private String deptname;

    public int getDeptno() {
        return deptno;
    }

    public void setDeptno(int deptno) {
        this.deptno = deptno;
    }

    public String getDeptname() {
        return deptname;
    }

    public void setDeptname(String deptname) {
        this.deptname = deptname;
    }
}

-----------------------------------------------------------------------------------<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
        "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
        "http://www.hibernaate.net/dtd/hibernate-mapping-3.0.dtd">
<hibernate-mapping package="cn.happy.manytoone">
    <class name="Dept" schema="guohua">
        <id name="deptno">
            <!-- 算法的核心思想是结合机器的网卡、当地时间、一个随机数来生成GUID -->
            <generator class="native"></generator>
        </id>
        <property name="deptname"/>

    </class>
</hibernate-mapping>
--------------------------------------------------------------------------------------
package cn.happy.manytoone;

/**
 * Created by guo on 2017/10/6.
 */
public class Emp
{
    private int empno;
    private String ename;
    private Dept dept=new Dept();

    public Dept getDept() {
        return dept;
    }

    public void setDept(Dept dept) {
        this.dept = dept;
    }

    public int getEmpno() {
        return empno;
    }

    public void setEmpno(int empno) {
        this.empno = empno;
    }

    public String getEname() {
        return ename;
    }

    public void setEname(String ename) {
        this.ename = ename;
    }
}
---------------------------------------------------------------------

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
        "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
        "http://www.hibernaate.net/dtd/hibernate-mapping-3.0.dtd">
<hibernate-mapping package="cn.happy.manytoone">
    <class name="Emp" schema="guohua">
        <id name="empno">
            <!-- 算法的核心思想是结合机器的网卡、当地时间、一个随机数来生成GUID -->
            <generator class="native"></generator>
        </id>
        <property name="ename"/>
        <many-to-one name="dept" column="deptno" class="Dept"></many-to-one>
    </class>
</hibernate-mapping>

-----------------------------------------------------------------------------------------------------------------------------------------------------------

2.编写大配置文件

<!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>
        <!-- 数据库链接-->
        <property name="connection.driver_class">oracle.jdbc.OracleDriver</property>
        <property name="connection.url">jdbc:oracle:thin:@localhost:1521:orcl</property>
        <property name="connection.username">guohua</property>
        <property name="connection.password">123456</property>
        <!-- 辅助参数-->
        <property name="show_sql">true</property>
        <property name="hbm2ddl.auto">update</property>
        <property name="format_sql">true</property>
        <property name="dialect">org.hibernate.dialect.Oracle10gDialect</property>
       <!-- <property name="current_session_context_class">thread</property>-->
        <mapping resource="cn/happy/manytoone/Dept.hbm.xml"/>
        <mapping resource="cn/happy/manytoone/Emp.hbm.xml"/>
        <mapping resource="cn/happy/onetomanydouble/Dept.hbm.xml"/>
        <mapping resource="cn/happy/onetomanydouble/Emp.hbm.xml"/>
        <mapping resource="cn/happy/manytomany/Employee.hbm.xml"/>
        <mapping resource="cn/happy/manytomany/Project.hbm.xml"/>
    </session-factory>
</hibernate-configuration>

----------------------------------------------------------------------------------------------------------

3.编写测试类

package cn.happy.test;

import cn.happy.manytoone.Emp;
import cn.happy.util.sessionUtil;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.cfg.Configuration;

/**
 * Created by guo on 2017/10/6.
 */
public class manytoone {
    public static void main(String[] args) {
        Configuration cfg = new Configuration().configure();
        SessionFactory factory = cfg.buildSessionFactory();
        //Session session = factory.openSession();
        Session session = sessionUtil.getSession();
        Transaction tx = session.beginTransaction();


        Emp emp = session.get(Emp.class, 1);
        System.out.println(emp.getDept().getDeptname());


        tx.commit();
        session.close();
    }
}