6.Hibernate单向的多对一 关联映射

1.创建如下项目结构

2.在项目的src下创建hibernate.cfg.xml主配置文件

 <?xml version="1.0" encoding="UTF-8"?>
 <!DOCTYPE hibernate-configuration PUBLIC "-//Hibernate/Hibernate Configuration DTD 3.0//EN" "http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd" >
 <hibernate-configuration>
   <session-factory>
      <property name="connection.driver_class">oracle.jdbc.driver.OracleDriver</property>
      <property name="connection.url">jdbc:oracle:thin:@127.0.0.1:1521:orcl</property>
      <property name="connection.username">scott</property>
      <property name="connection.password">tiger</property>
      <property name="dialect">org.hibernate.dialect.Oracle10gDialect</property>
      <property name="show_sql">true</property>
      <property name="format_sql">true</property>

      <mapping resource="com/entity/Dept.hbm.xml"/>
      <mapping resource="com/entity/Emp.hbm.xml"/>
   </session-factory>
 </hibernate-configuration>

hibernate.cfg.xml

3.在项目的src下的com.entity包下创建Dept.java

 package com.entity;

 public class Dept {
     /**
      * 部门编号
      */
     private int deptno;
     /**
      * 部门名称
      */
     private String dname;
     /**
      * 部门位置
      */
     private String loc;
     public Dept() {
     }
     public Dept(int deptno, String dname, String loc) {
         this.deptno = deptno;
         this.dname = dname;
         this.loc = loc;
     }
     public int getDeptno() {
         return deptno;
     }
     public void setDeptno(int deptno) {
         this.deptno = deptno;
     }
     public String getDname() {
         return dname;
     }
     public void setDname(String dname) {
         this.dname = dname;
     }
     public String getLoc() {
         return loc;
     }
     public void setLoc(String loc) {
         this.loc = loc;
     }
     @Override
     public String toString() {
         return "Dept [deptno=" + deptno + ", dname=" + dname + ", loc=" + loc
                 + "]";
     }

 }

Dept

4.在项目的src下的com.entity包下创建Emp.java

 package com.entity;

 import java.util.Date;

 public class Emp {
     /**
      * 员工编号
      */
     private Integer empno;
     /**
      * 员工姓名
      */
     private String ename;
     /**
      * 员工工作
      */
     private String job;
     /**
      * 员工领导编号
      */
     private Integer mgr;
     /**
      * 员工雇佣日期
      */
     private Date hiredate;
     /**
      * 员工工资
      */
     private Integer sal;
     /**
      * 员工奖金
      */
     private Integer comm;
     /**
      * 部门外键
      * 引入部门对象
      */
     private Dept dept;
     public Emp() {
         super();
     }
     public Emp(Integer empno, String ename, String job, Integer mgr,
             Date hiredate, Integer sal, Integer comm, Dept dept) {
         this.empno = empno;
         this.ename = ename;
         this.job = job;
         this.mgr = mgr;
         this.hiredate = hiredate;
         this.sal = sal;
         this.comm = comm;
         this.dept = dept;
     }

     public Integer getEmpno() {
         return empno;
     }
     public void setEmpno(Integer empno) {
         this.empno = empno;
     }
     public String getEname() {
         return ename;
     }
     public void setEname(String ename) {
         this.ename = ename;
     }
     public String getJob() {
         return job;
     }
     public void setJob(String job) {
         this.job = job;
     }
     public Integer getMgr() {
         return mgr;
     }
     public void setMgr(Integer mgr) {
         this.mgr = mgr;
     }
     public Date getHiredate() {
         return hiredate;
     }
     public void setHiredate(Date hiredate) {
         this.hiredate = hiredate;
     }
     public Integer getSal() {
         return sal;
     }
     public void setSal(Integer sal) {
         this.sal = sal;
     }
     public Integer getComm() {
         return comm;
     }
     public void setComm(Integer comm) {
         this.comm = comm;
     }
     public Dept getDept() {
         return dept;
     }
     public void setDept(Dept dept) {
         this.dept = dept;
     }
     @Override
     public String toString() {
         return "Emp [comm=" + comm + ", dept=" + dept + ", empno=" + empno
                 + ", ename=" + ename + ", hiredate=" + hiredate + ", job="
                 + job + ", mgr=" + mgr + ", sal=" + sal + "]";
     }

 }

Emp.java

5.在项目的src下的com.entity包下创建Dept.hbm.xml

 <?xml version="1.0" encoding="UTF-8"?>
 <!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.entity.Dept" table="DEPT" schema="SCOTT">
   <!-- 主键配置 -->
    <id name="deptno" type="java.lang.Integer" column="DEPTNO">
       <!-- 主键由应用程序负责生成 -->
       <generator class="assigned"/>
    </id>
    <!-- 部门名称 -->
    <property name="dname" type="java.lang.String" column="DNAME"/>

    <!-- 部门位置 -->
    <property name="loc" type="java.lang.String" column="LOC"/>
 </class>
 </hibernate-mapping>

Dept.hbm.xml

6.在项目的src下的com.entity包下创建Emp.hbm.xml

 <?xml version="1.0" encoding="UTF-8"?>
 <!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.entity.Emp" table="EMP" schema="scott">
       <id name="empno" type="java.lang.Integer" column="EMPNO">
          <generator class="assigned"/>
       </id>
       <property name="ename" type="java.lang.String" column="ENAME"/>
       <property name="job" type="java.lang.String" column="JOB"/>
       <property name="mgr" type="java.lang.Integer" column="MGR"/>
       <property name="hiredate" type="java.util.Date" column="HIREDATE"/>
       <property name="sal" type="java.lang.Integer" column="SAL"/>
       <property name="comm" type="java.lang.Integer" column="COMM" not-null="false" />

       <!-- 多对一映射：name是emp中外键字段引用的对象，class是对象的类型，column是数据库中对应的外键列字段名 -->
       <many-to-one name="dept" class="com.entity.Dept" column="DEPTNO"/>
    </class>
 </hibernate-mapping>

Emp.hbm.xml

7.在项目的src下的com.util包下创建HibernateUtil.java

 package com.util;

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

 public class HibernateUtil {
     /**
      * 创建线程池来管理Session
      */
     private static ThreadLocal<Session> thread=new ThreadLocal<Session>();
     /**
      * 创建读取配置文件的对象
      */
     private static Configuration config=null;
     /**
      * 创建获取Session的工厂
      */
     private static SessionFactory factory=null;

     /**
      * 读取配置文件
      */
     static{
         try {
             config=new Configuration().configure("/hibernate.cfg.xml");
             factory=config.buildSessionFactory();
         } catch (HibernateException e) {
             System.out.println("读取配置文件或创建SessionFactory失败！");
             e.printStackTrace();
         }
     }

     /**
      * 获取session
      * @return
      */
     public static Session getSession(){
         Session session=thread.get();
         if(session==null){
             session=factory.openSession();
             thread.set(session);
         }
         return session;
     }

     /**
      * 关闭Session
      */
     public static void closeSession(){
         Session session=thread.get();
         thread.set(null);
         session.close();
     }

 }

HibernateUtil.java

8.在项目的src下的com.dao包下创建EmpDao.java

 package com.dao;

 import java.text.ParseException;
 import java.text.SimpleDateFormat;
 import java.util.Date;
 import java.util.List;
 import java.util.logging.SimpleFormatter;

 import org.hibernate.Query;
 import org.hibernate.Session;
 import org.hibernate.Transaction;

 import com.entity.Dept;
 import com.entity.Emp;
 import com.util.HibernateUtil;

 public class EmpDao {

     public static void main(String[] args) {
         System.out.println("--------------------1.保存：1部门和2员工-----3条sql------------------");
         //saveEmp();
         System.out.println("----------------2.根据部门编号，查询该部门下的所有员工--2条sql--------------");
         //getEmpByDeptNo(1);
         System.out.println("----------------3.查询所有员工--5条sql--------------");
         //getEmp();
         System.out.println("----------------4.删除--------------------------------------");
         //deleteEmp(1);

         System.out.println("-----------------5.修改-----2个sql---------------------");
         updateEmp(2);

     }
     /**
      * 5.修改
      * @param i
      */
     private static void updateEmp(int id) {
         Session session=HibernateUtil.getSession();
         //2.开启事务
         Transaction tx=session.beginTransaction();
         //查单条
         Emp emp=(Emp) session.get(Emp.class, id);
         if(emp!=null){
             emp.setEname("小猪");
             System.out.println("修改成功");
         }else{
             System.out.println("该条数据不存在");
         }
         tx.commit();
         HibernateUtil.closeSession();

     }
     /**
      * 4.删除
      * @param id
      */
     private static void deleteEmp(int id) {
         Session session=HibernateUtil.getSession();
         //2.开启事务
         Transaction tx=session.beginTransaction();
         //查单条
         Emp emp=(Emp) session.get(Emp.class, id);
         if(emp!=null){
             session.delete(emp);
             System.out.println("删除成功");
         }else{
             System.out.println("该条数据不存在");
         }
         tx.commit();
         HibernateUtil.closeSession();

     }
     /**
      * -3.查询所有员工--2条sql
      * 如果会报出： Null value was assigned to a property of primitive type setter of com.entity.Emp.comm异常
      * 表示comm奖金字段为null，映射是Integer类型，而实体类里是int类型，int基本数据类型值没有null，所以报错
      * 解决方法：将实体类所有字段数据类型改为引用数据类型
      */
     private static void getEmp() {
         Session session=HibernateUtil.getSession();
         String hql="from Emp";
         Query query=session.createQuery(hql);
         List<Emp> list=query.list();
         for (Emp emp : list) {
             System.out.println("部门编号："+emp.getDept().getDeptno()+"\t部门名称："+emp.getDept().getDname()+"\t员工姓名："+emp.getEname());
         }

         HibernateUtil.closeSession();

     }
     /**
      * 2.根据部门编号，查询该部门下的所有员工
      * 2条sql
      * @param i
      */
     private static void getEmpByDeptNo(int id) {
         //1.开启Session
         Session session=HibernateUtil.getSession();

         String hql="from Emp e where e.dept.deptno=:pdeptno";
         Query query=session.createQuery(hql);
         query.setParameter("pdeptno", id);
         List<Emp> list=query.list();
         for (Emp emp : list) {
             System.out.println(emp);
         }
         //5.关闭Session
         HibernateUtil.closeSession();

     }
     /**
      * 1.保存：1部门和2员工-----3条sql
      */
     private static void saveEmp() {
         //1.开启Session
         Session session=HibernateUtil.getSession();

         //2.开启事务
         Transaction tx=session.beginTransaction();

         //3.执行操作
         //创建部门对象
         Dept dept=new Dept(1, "质控部", "中部");

         //保存dept对象
         session.save(dept);
         System.out.println("Dept保存成功");

         Date date=null;
         try {
             date = new SimpleDateFormat("yyyy-MM-dd").parse("2013-3-3");
         } catch (ParseException e) {
             e.printStackTrace();
         }

         //创建员工对象
         Emp emp1=new Emp(1, "holly", "教员", 2, date, 2300, 200, dept);
         Emp emp2=new Emp(2, "猪猪", "领导", 1, date, 3000, 200, dept);

         //保存Emp对象
         session.save(emp1);

         //保存Emp对象
         session.save(emp2);
         System.out.println("Emp保存成功");

         //4.提交事务
         tx.commit();

         //5.关闭Session
         HibernateUtil.closeSession();
     }

 }

EmpDao.java

9.结果自己验证...