hibernate 进行一对多查询时，多的一方外键有记录，但为什么是null

l5038814 2014-06-07 05:07:29

部门.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 package="com.aa.model">

<class name="Department" table="Department"  >

 <id name="id" type="java.lang.Integer">

  <generator class="native"></generator> 

 </id>

 <property name="name" type="java.lang.String">

  <column name="name"></column>

 </property>

 <set name="stus"  cascade="all">

   <key column="departid"  />                        

   <one-to-many  class="Student" />

 </set>

</class>

</hibernate-mapping>

学生.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 package="com.aa.model">

<class name="Student" table="Student" > 

 <id name="id" type="java.lang.Integer">

 <generator class="native"></generator> 

 </id>

 <property name="name" type="java.lang.String">

  <column name="name"></column>

 </property>

 <many-to-one name="depart" cascade="all" class="Department">

 <column name="departid"></column>

 </many-to-one>

</class>

</hibernate-mapping>



部门类

public class Department implements Serializable {



	/**

	 * 

	 */

	private static final long serialVersionUID = 1L;

	private int id;

	private String name;

	private Set<Student> stus;}



学生类

public class Student implements Serializable {



	/**

	 * 

	 */

	private static final long serialVersionUID = 1L;

	private int id;

	private String name;

	private Department depart;

	private String departid;}

测试代码



			session=HibernateUtil.getCurrentSession();

			//tx=session.beginTransaction();	

			Department d=(Department)session.get(Department.class, 2);

			Set<Student> stus=d.getStus();

			for(Student s:stus){

				        s.setDepart(d);

						System.out.println(s.getId()+s.getName()+s.getDepartid());

s.getId()+s.getName()都能取出，唯独s.getDepartid() 为什么是null

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