hibernate_关联映射_多对一

 1 package com.imooc.entity;
 2 
 3 import java.io.Serializable;
 4 
 5 public class Student implements Serializable {
 6 
 7     private int sid;
 8     private String sname;
 9     private String sex;
10     // 在多方定义一个一方的引用
11     private Grade grade;
12     
13     public int getSid() {
14         return sid;
15     }
16     public void setSid(int sid) {
17         this.sid = sid;
18     }
19     public String getSname() {
20         return sname;
21     }
22     public void setSname(String sname) {
23         this.sname = sname;
24     }
25     public String getSex() {
26         return sex;
27     }
28     public void setSex(String sex) {
29         this.sex = sex;
30     }
31     public Grade getGrade() {
32         return grade;
33     }
34     public void setGrade(Grade grade) {
35         this.grade = grade;
36     }
37     
38     public Student() {
39         super();
40     }
41     
42     public Student(String sname, String sex) {
43         super();
44         this.sname = sname;
45         this.sex = sex;
46     }
47     
48 }

 1 package com.imooc.entity;
 2 
 3 import java.io.Serializable;
 4 import java.util.HashSet;
 5 import java.util.Set;
 6 
 7 
 8 public class Grade implements Serializable {
 9 
10     private int gid;
11     private String gname;
12     private String gdesc;
13     private Set<Student> students = new HashSet<Student>();
14     
15     public int getGid() {
16         return gid;
17     }
18     public void setGid(int gid) {
19         this.gid = gid;
20     }
21     public String getGname() {
22         return gname;
23     }
24     public void setGname(String gname) {
25         this.gname = gname;
26     }
27     public String getGdesc() {
28         return gdesc;
29     }
30     public void setGdesc(String gdesc) {
31         this.gdesc = gdesc;
32     }
33     public Set<Student> getStudents() {
34         return students;
35     }
36     public void setStudents(Set<Student> students) {
37         this.students = students;
38     }
39     
40     public Grade() {
41         super();
42     }
43     
44     public Grade(int gid, String gname, String gdesc) {
45         super();
46         this.gid = gid;
47         this.gname = gname;
48         this.gdesc = gdesc;
49     }
50     
51     public Grade(String gname, String gdesc) {
52         super();
53         this.gname = gname;
54         this.gdesc = gdesc;
55     }
56 }

 1 <?xml version="1.0"?>
 2 <!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
 3 "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
 4 <!-- Generated 2017-6-1 14:49:09 by Hibernate Tools 3.5.0.Final -->
 5 <hibernate-mapping>
 6     <class name="com.imooc.entity.Student" table="STUDENT">
 7         <id name="sid" type="int">
 8             <column name="SID" />
 9             <generator class="increment" />
10         </id>
11         <property name="sname" type="java.lang.String">
12             <column name="SNAME" />
13         </property>
14         <property name="sex" type="java.lang.String">
15             <column name="SEX" />
16         </property>
17         <!-- 配置多对一关联关系 -->
18         <many-to-one name="grade" class="com.imooc.entity.Grade" column="gid" cascade="all"></many-to-one>
19     </class>
20 </hibernate-mapping>

 1 <?xml version="1.0"?>
 2 <!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
 3 "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
 4 <!-- Generated 2017-6-1 14:49:09 by Hibernate Tools 3.5.0.Final -->
 5 <hibernate-mapping>
 6     <class name="com.imooc.entity.Grade" table="GRADE">
 7         <id name="gid" type="int">
 8             <column name="GID" />
 9             <generator class="increment" />
10         </id>
11         <property name="gname" type="java.lang.String">
12             <column name="GNAME" length="20" not-null="true" />
13         </property>
14         <property name="gdesc" type="java.lang.String">
15             <column name="GDESC" />
16         </property>
17     </class>
18 </hibernate-mapping>

 1 <?xml version="1.0" encoding="UTF-8"?>
 2 <!DOCTYPE hibernate-configuration PUBLIC
 3         "-//Hibernate/Hibernate Configuration DTD 3.0//EN"
 4         "http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd">
 5 <hibernate-configuration>
 6     <session-factory>
 7         <property name="connection.username">root</property>
 8         <property name="connection.password">root</property>
 9         <property name="connection.driver_class">com.mysql.jdbc.Driver</property>
10         <property name="connection.url">
11             <![CDATA[
12                 jdbc:mysql://localhost:3306/hibernate?useUnicode=true&amp;characterEncoding=UTF-8
13             ]]>
14         </property>
15         <property name="dialect">org.hibernate.dialect.MySQLDialect</property>
16         <property name="show_sql">true</property>
17         <property name="format_sql">true</property>
18         <property name="hbm2ddl.auto">update</property>
19         
20         <!-- 指定映射文件的路径 -->
21         <mapping resource="com/imooc/entity/Grade.hbm.xml" />
22         <mapping resource="com/imooc/entity/Student.hbm.xml" />
23     </session-factory>
24 </hibernate-configuration>

 1 package com.imooc.test;
 2 
 3 import org.hibernate.Session;
 4 import org.hibernate.Transaction;
 5 
 6 import com.imooc.entity.Grade;
 7 import com.imooc.entity.Student;
 8 import com.imooc.util.HibernateUtil;
 9 
10 /*
11  * 单向多对一（学生--->班级）
12  */
13 public class Test {
14 
15     public static void main(String[] args) {
16         save();
17     }
18     
19     public static void save() {
20         Grade g = new Grade("java一班", "Java软件开发一班");
21         Student s1 = new Student("杨过","男");
22         Student s2 = new Student("小龙女", "女");
23         
24         // 设置关联关系
25         g.getStudents().add(s1);
26         g.getStudents().add(s2);
27         s1.setGrade(g);
28         s2.setGrade(g);
29         
30         Session session = HibernateUtil.getSession();
31         Transaction tr = session.beginTransaction();
32         session.save(g);
33         session.save(s1);
34         session.save(s2);
35         tr.commit();
36         HibernateUtil.closeSession(session);
37     }
38 }