配置文件：
班级：
<hibernate-mapping>
 
 <class name="bjca.testHibernate.entity.impl.ClassInfo" table="t_class">
   <id name="claId" type="java.lang.Integer">
            <column name="claId" />
            <generator class="native" />
        </id>
  <property name="claName" type="java.lang.String">
            <column name="claName" length="50" not-null="true" />
        </property>
      
  <set name="students" inverse="true">
   <key column="classId"></key>
   <one-to-many class="bjca.testHibernate.entity.impl.StudentInfo"/>
  </set>
  
     </class>
</hibernate-mapping>

学生
<hibernate-mapping>
 
 <class name="bjca.testHibernate.entity.impl.StudentInfo" table="t_student">
   <id name="stuId" type="java.lang.Integer">
            <column name="id" />          
             <generator class="native" />
        </id>
  <property name="stuName" type="java.lang.String">
            <column name="stuName" length="50" not-null="true" />
        </property>
       
        <many-to-one name="classes" column="classId"

class="bjca.testHibernate.entity.impl.ClassInfo" cascade="all"/>
 </class>
</hibernate-mapping>

插入一个班级：
log4j:WARN No appenders could be found for logger (org.hibernate.cfg.Environment).
log4j:WARN Please initialize the log4j system properly.
Hibernate: select hibernate_sequence.nextval from dual
Hibernate: insert into t_class (claName, claId) values (?, ?)
11111

插入一个学生：
log4j:WARN No appenders could be found for logger (org.hibernate.cfg.Environment).
log4j:WARN Please initialize the log4j system properly.
Hibernate: select hibernate_sequence.nextval from dual
Hibernate: insert into t_student (stuName, classId, id) values (?, ?, ?)
11111

修改一条学生信息：
11111
log4j:WARN No appenders could be found for logger (org.hibernate.cfg.Environment).
log4j:WARN Please initialize the log4j system properly.
Hibernate: select studentinf0_.id as id0_, studentinf0_.stuName as stuName0_,

studentinf0_.classId as classId0_ from t_student studentinf0_ where studentinf0_.id=10
Hibernate: select classinfo0_.claId as claId1_, classinfo0_.claName as claName1_ from t_class

classinfo0_ where classinfo0_.claId=11
Hibernate: select studentinf0_.id as id0_0_, studentinf0_.stuName as stuName0_0_,

studentinf0_.classId as classId0_0_ from t_student studentinf0_ where studentinf0_.id=?
Hibernate: update t_student set stuName=?, classId=? where id=?
Hibernate: update t_class set claName=? where claId=?

修改一条班级信息：
11111
log4j:WARN No appenders could be found for logger (org.hibernate.cfg.Environment).
log4j:WARN Please initialize the log4j system properly.
Hibernate: select classinfo0_.claId as claId1_, classinfo0_.claName as claName1_ from t_class

classinfo0_ where classinfo0_.claId=11
Hibernate: update t_class set claName='大象二班' where claId=11

班级信息级联 all
11111
log4j:WARN No appenders could be found for logger (org.hibernate.cfg.Environment).
log4j:WARN Please initialize the log4j system properly.
Hibernate: select studentinf0_.id as id0_, studentinf0_.stuName as stuName0_,

studentinf0_.classId as classId0_ from t_student studentinf0_ where studentinf0_.id=12
Hibernate: select classinfo0_.claId as claId1_, classinfo0_.claName as claName1_ from t_class

classinfo0_ where classinfo0_.claId=11
Hibernate: select studentinf0_.id as id0_0_, studentinf0_.stuName as stuName0_0_,

studentinf0_.classId as classId0_0_ from t_student studentinf0_ where studentinf0_.id=?
Hibernate: update t_class set claName=? where claId=?

结论：
1对多，多的那方 cascade="all"

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1方， 班级：       
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实体类包含set对象，放置多方对象 名自取

配置文件中配置<set>标记,标记name取本方实体中的对方set对象的名字，即set的名字 ,
<set> 下的 <key> 指向多方主键
<set> 下的 <one-to-many> 指向多方对象

***********************************
多方  学生：       
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实体类包含1方对象，名自取

配置文件中配置<many-to-one> 指向1方对象 name 属性取本方实体方法中的对方对象的名字。