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

 1 <?xml version="1.0" encoding="UTF-8"?>
 2 <!DOCTYPE hibernate-configuration PUBLIC "-//Hibernate/Hibernate Configuration DTD 3.0//EN" "http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd" >
 3 <hibernate-configuration>
 4   <session-factory>
 5      <property name="connection.driver_class">oracle.jdbc.driver.OracleDriver</property>
 6      <property name="connection.url">jdbc:oracle:thin:@127.0.0.1:1521:orcl</property>
 7      <property name="connection.username">scott</property>
 8      <property name="connection.password">tiger</property>
 9      <property name="dialect">org.hibernate.dialect.Oracle10gDialect</property>
10      <property name="show_sql">true</property>
11      <property name="format_sql">true</property>
12      
13      <mapping resource="com/entity/Dept.hbm.xml"/>
14      <mapping resource="com/entity/Emp.hbm.xml"/>
15   </session-factory>
16 </hibernate-configuration>

hibernate.cfg.xml

3.在项目的src下的com.entity包下创建Dept.java

 1 package com.entity;
 2 
 3 public class Dept {
 4     /**
 5      * 部门编号
 6      */
 7     private int deptno;
 8     /**
 9      * 部门名称
10      */
11     private String dname;
12     /**
13      * 部门位置
14      */
15     private String loc;
16     public Dept() {
17     }
18     public Dept(int deptno, String dname, String loc) {
19         this.deptno = deptno;
20         this.dname = dname;
21         this.loc = loc;
22     }
23     public int getDeptno() {
24         return deptno;
25     }
26     public void setDeptno(int deptno) {
27         this.deptno = deptno;
28     }
29     public String getDname() {
30         return dname;
31     }
32     public void setDname(String dname) {
33         this.dname = dname;
34     }
35     public String getLoc() {
36         return loc;
37     }
38     public void setLoc(String loc) {
39         this.loc = loc;
40     }
41     @Override
42     public String toString() {
43         return "Dept [deptno=" + deptno + ", dname=" + dname + ", loc=" + loc
44                 + "]";
45     }
46     
47 
48 }

Dept

4.在项目的src下的com.entity包下创建Emp.java

  1 package com.entity;
  2 
  3 import java.util.Date;
  4 
  5 public class Emp {
  6     /**
  7      * 员工编号
  8      */
  9     private Integer empno;
 10     /**
 11      * 员工姓名
 12      */
 13     private String ename;
 14     /**
 15      * 员工工作
 16      */
 17     private String job;
 18     /**
 19      * 员工领导编号
 20      */
 21     private Integer mgr;
 22     /**
 23      * 员工雇佣日期
 24      */
 25     private Date hiredate;
 26     /**
 27      * 员工工资
 28      */
 29     private Integer sal;
 30     /**
 31      * 员工奖金
 32      */
 33     private Integer comm;
 34     /**
 35      * 部门外键
 36      * 引入部门对象
 37      */
 38     private Dept dept;
 39     public Emp() {
 40         super();
 41     }
 42     public Emp(Integer empno, String ename, String job, Integer mgr,
 43             Date hiredate, Integer sal, Integer comm, Dept dept) {
 44         this.empno = empno;
 45         this.ename = ename;
 46         this.job = job;
 47         this.mgr = mgr;
 48         this.hiredate = hiredate;
 49         this.sal = sal;
 50         this.comm = comm;
 51         this.dept = dept;
 52     }
 53     
 54     public Integer getEmpno() {
 55         return empno;
 56     }
 57     public void setEmpno(Integer empno) {
 58         this.empno = empno;
 59     }
 60     public String getEname() {
 61         return ename;
 62     }
 63     public void setEname(String ename) {
 64         this.ename = ename;
 65     }
 66     public String getJob() {
 67         return job;
 68     }
 69     public void setJob(String job) {
 70         this.job = job;
 71     }
 72     public Integer getMgr() {
 73         return mgr;
 74     }
 75     public void setMgr(Integer mgr) {
 76         this.mgr = mgr;
 77     }
 78     public Date getHiredate() {
 79         return hiredate;
 80     }
 81     public void setHiredate(Date hiredate) {
 82         this.hiredate = hiredate;
 83     }
 84     public Integer getSal() {
 85         return sal;
 86     }
 87     public void setSal(Integer sal) {
 88         this.sal = sal;
 89     }
 90     public Integer getComm() {
 91         return comm;
 92     }
 93     public void setComm(Integer comm) {
 94         this.comm = comm;
 95     }
 96     public Dept getDept() {
 97         return dept;
 98     }
 99     public void setDept(Dept dept) {
100         this.dept = dept;
101     }
102     @Override
103     public String toString() {
104         return "Emp [comm=" + comm + ", dept=" + dept + ", empno=" + empno
105                 + ", ename=" + ename + ", hiredate=" + hiredate + ", job="
106                 + job + ", mgr=" + mgr + ", sal=" + sal + "]";
107     }
108     
109     
110     
111     
112     
113 
114 }

Emp.java

5.在项目的src下的com.entity包下创建Dept.hbm.xml

 1 <?xml version="1.0" encoding="UTF-8"?>
 2 <!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN" "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd" >
 3 <hibernate-mapping>
 4 <class name="com.entity.Dept" table="DEPT" schema="SCOTT">
 5   <!-- 主键配置 -->
 6    <id name="deptno" type="java.lang.Integer" column="DEPTNO">
 7       <!-- 主键由应用程序负责生成 -->
 8       <generator class="assigned"/> 
 9    </id>
10    <!-- 部门名称 -->
11    <property name="dname" type="java.lang.String" column="DNAME"/>
12    
13    <!-- 部门位置 -->
14    <property name="loc" type="java.lang.String" column="LOC"/>
15 </class>
16 </hibernate-mapping>

Dept.hbm.xml

6.在项目的src下的com.entity包下创建Emp.hbm.xml

 1 <?xml version="1.0" encoding="UTF-8"?>
 2 <!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN" "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd" >
 3 <hibernate-mapping>
 4    <class name="com.entity.Emp" table="EMP" schema="scott">
 5       <id name="empno" type="java.lang.Integer" column="EMPNO">
 6          <generator class="assigned"/>
 7       </id>
 8       <property name="ename" type="java.lang.String" column="ENAME"/>
 9       <property name="job" type="java.lang.String" column="JOB"/>
10       <property name="mgr" type="java.lang.Integer" column="MGR"/>
11       <property name="hiredate" type="java.util.Date" column="HIREDATE"/>
12       <property name="sal" type="java.lang.Integer" column="SAL"/>
13       <property name="comm" type="java.lang.Integer" column="COMM" not-null="false" />
14       
15       <!-- 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 -->
16       <many-to-one name="dept" class="com.entity.Dept" column="DEPTNO"/>   
17    </class>
18 </hibernate-mapping>

Emp.hbm.xml

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

 1 package com.util;
 2 
 3 import org.hibernate.HibernateException;
 4 import org.hibernate.Session;
 5 import org.hibernate.SessionFactory;
 6 import org.hibernate.cfg.Configuration;
 7 
 8 public class HibernateUtil {
 9     /**
10      * 创建线程池来管理Session
11      */
12     private static ThreadLocal<Session> thread=new ThreadLocal<Session>();
13     /**
14      * 创建读取配置文件的对象
15      */
16     private static Configuration config=null;
17     /**
18      * 创建获取Session的工厂
19      */
20     private static SessionFactory factory=null;
21     
22     /**
23      * 读取配置文件
24      */
25     static{
26         try {
27             config=new Configuration().configure("/hibernate.cfg.xml");
28             factory=config.buildSessionFactory();
29         } catch (HibernateException e) {
30             System.out.println("读取配置文件或创建SessionFactory失败！");
31             e.printStackTrace();
32         }
33     }
34     
35     /**
36      * 获取session
37      * @return
38      */
39     public static Session getSession(){
40         Session session=thread.get();
41         if(session==null){
42             session=factory.openSession();
43             thread.set(session);
44         }
45         return session;
46     }
47     
48     /**
49      * 关闭Session
50      */
51     public static void closeSession(){
52         Session session=thread.get();
53         thread.set(null);
54         session.close();
55     }
56     
57 
58 }

HibernateUtil.java

8.在项目的src下的com.dao包下创建EmpDao.java

  1 package com.dao;
  2 
  3 import java.text.ParseException;
  4 import java.text.SimpleDateFormat;
  5 import java.util.Date;
  6 import java.util.List;
  7 import java.util.logging.SimpleFormatter;
  8 
  9 import org.hibernate.Query;
 10 import org.hibernate.Session;
 11 import org.hibernate.Transaction;
 12 
 13 import com.entity.Dept;
 14 import com.entity.Emp;
 15 import com.util.HibernateUtil;
 16 
 17 public class EmpDao {
 18     
 19     public static void main(String[] args) {
 20         System.out.println("--------------------1.保存：1部门和2员工-----3条sql------------------");
 21         //saveEmp();
 22         System.out.println("----------------2.根据部门编号，查询该部门下的所有员工--2条sql--------------");
 23         //getEmpByDeptNo(1);
 24         System.out.println("----------------3.查询所有员工--5条sql--------------");
 25         //getEmp();
 26         System.out.println("----------------4.删除--------------------------------------");
 27         //deleteEmp(1);
 28         
 29         System.out.println("-----------------5.修改-----2个sql---------------------");
 30         updateEmp(2);
 31         
 32     }
 33     /**
 34      * 5.修改
 35      * @param i
 36      */
 37     private static void updateEmp(int id) {
 38         Session session=HibernateUtil.getSession();
 39         //2.开启事务
 40         Transaction tx=session.beginTransaction();
 41         //查单条
 42         Emp emp=(Emp) session.get(Emp.class, id);
 43         if(emp!=null){
 44             emp.setEname("小猪");
 45             System.out.println("修改成功");
 46         }else{
 47             System.out.println("该条数据不存在");
 48         }
 49         tx.commit();
 50         HibernateUtil.closeSession();
 51         
 52     }
 53     /**
 54      * 4.删除
 55      * @param id
 56      */
 57     private static void deleteEmp(int id) {
 58         Session session=HibernateUtil.getSession();
 59         //2.开启事务
 60         Transaction tx=session.beginTransaction();
 61         //查单条
 62         Emp emp=(Emp) session.get(Emp.class, id);
 63         if(emp!=null){
 64             session.delete(emp);
 65             System.out.println("删除成功");
 66         }else{
 67             System.out.println("该条数据不存在");
 68         }
 69         tx.commit();
 70         HibernateUtil.closeSession();
 71         
 72     }
 73     /**
 74      * -3.查询所有员工--2条sql
 75      * 如果会报出： Null value was assigned to a property of primitive type setter of com.entity.Emp.comm异常
 76      * 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
 77      * 解决方法：将实体类所有字段数据类型改为引用数据类型
 78      */
 79     private static void getEmp() {
 80         Session session=HibernateUtil.getSession();
 81         String hql="from Emp";
 82         Query query=session.createQuery(hql);
 83         List<Emp> list=query.list();
 84         for (Emp emp : list) {
 85             System.out.println("部门编号："+emp.getDept().getDeptno()+"	部门名称："+emp.getDept().getDname()+"	员工姓名："+emp.getEname());
 86         }
 87         
 88         HibernateUtil.closeSession();
 89         
 90     }
 91     /**
 92      * 2.根据部门编号，查询该部门下的所有员工
 93      * 2条sql
 94      * @param i
 95      */
 96     private static void getEmpByDeptNo(int id) {
 97         //1.开启Session
 98         Session session=HibernateUtil.getSession();
 99         
100         String hql="from Emp e where e.dept.deptno=:pdeptno";
101         Query query=session.createQuery(hql);
102         query.setParameter("pdeptno", id);
103         List<Emp> list=query.list();
104         for (Emp emp : list) {
105             System.out.println(emp);
106         }
107         //5.关闭Session
108         HibernateUtil.closeSession();
109         
110     }
111     /**
112      * 1.保存：1部门和2员工-----3条sql
113      */
114     private static void saveEmp() {
115         //1.开启Session
116         Session session=HibernateUtil.getSession();
117         
118         //2.开启事务
119         Transaction tx=session.beginTransaction();
120         
121         //3.执行操作
122         //创建部门对象
123         Dept dept=new Dept(1, "质控部", "中部");
124         
125         //保存dept对象
126         session.save(dept);
127         System.out.println("Dept保存成功");
128     
129         Date date=null;
130         try {
131             date = new SimpleDateFormat("yyyy-MM-dd").parse("2013-3-3");
132         } catch (ParseException e) {
133             e.printStackTrace();
134         }
135         
136         //创建员工对象
137         Emp emp1=new Emp(1, "holly", "教员", 2, date, 2300, 200, dept);
138         Emp emp2=new Emp(2, "猪猪", "领导", 1, date, 3000, 200, dept);
139         
140         //保存Emp对象
141         session.save(emp1);
142         
143         //保存Emp对象
144         session.save(emp2);
145         System.out.println("Emp保存成功");
146         
147         //4.提交事务
148         tx.commit();
149         
150         //5.关闭Session
151         HibernateUtil.closeSession();
152     }
153 
154 }

EmpDao.java

9.结果自己验证...

相关阅读:
SQL通用数据类型
 SQL基础
 软件测试相关（1）
C语言——判断
 C语言新手教程——计算
 并查集
 洛谷-P1551 亲戚
 洛谷-P1536 村村通
 洛谷-P1525 [NOIP2010 提高组] 关押罪犯
 洛谷-P2814 家谱
原文地址：https://www.cnblogs.com/holly8/p/5759573.html

6.Hibernate单向的多对一 关联映射

6.Hibernate单向的多对一关联映射