1对多多对1双向映射.docVIP

一对多,多对一双向关联映射 以学院与专业为例说明: 学院与专业是典型的一对多关系. 设置一对多单向映射: 在college实体类中添加setDepartment集合类型的depart属性 private int coid; private String coname; private String conum; private SetDepartment depart=new HashSetDepartment(); 在college配置文件中配置one-to-many/one-to-many hibernate-mapping class name=com.pb.sims.entity.College table=COLLEGE schema=STUDENT id name=coid type=java.lang.Integer column name=COID precision=22 scale=0 / generator class=sequence param name=sequenceseq_college_coid/param /generator /id property name=coname type=java.lang.String column name=CONAME length=20 / /property property name=conum type=java.lang.String column name=CONUM length=3 / /property set name=depart key column=coid/ one-to-many class=com.pb.sims.entity.Department / /set /class /hibernate-mapping 如何查询某个学院下的若干个专业 //test one-to-many Session session=HibernateSessionFactory.getSession(); College co=(College)session.get(College.class, 1); //查询出学院id=1的学院 System.out.println(co.getCoid()+co.getConame()); //输出学院id 及 学院名称 SetDepartment set=co.getDepart(); IteratorDepartment it=set.iterator(); //将该学院下的专业，保存到迭代器中 while(it.hasNext()){ //使用迭代器将专业信息输出 Department de=new Department(); de=it.next(); System.out.println(de.getDename()); } 多对一单向关联 在depart实体类中，添加College类型的属性co private int deid; private String dename; private String denum; // private int coid; （注意，供应商的主键将不再需要） private College co; 在映射文件中配置，many-to-one hibernate-mapping class name=com.pb.sims.entity.Department table=DEPARTMENT schema=STUDENT id name=deid type=java.lang.Integer column name=DEID precision=22 scale=0 / generator class=sequence param name=sequenceSEQ_DEPARTMENT_DEID/param /generator /id property name=dename type=java.lang.