有两个实体类User和Department。建立双向多对一关联。
User是多的一端
@Entity
public class User implements Serializable{
@Id
@GeneratedValue(strategy=GenerationType.IDENTITY)
@Column(name="id")
private Integer id;
@Column(name="name")
private String name;
@Column(name="age")
private Integer age;
@ManyToOne(cascade=CascadeType.ALL)
@JoinColumn(name="department_id")
private Department department;
}
Department是一的一端
@Entity
public class Department {
@Id
@GeneratedValue(strategy=GenerationType.IDENTITY)
@Column(name="id")
private Integer id;
@Column(name="name")
private String name;
@OneToMany(mappedBy="department" , cascade=CascadeType.ALL)
private Set<User> user;
}
数据库中有如图的数据：
User表：
Department表：
通过jsp新增一个User
<form:form action="${pageContext.request.contextPath}/add" method="post" commandName="User">
<table>
<tr>
<td>Name:</td> <td><form:input path="name"/></td>
</tr>
<tr>
<td>Age:</td> <td><form:input path="age"/></td>
</tr>
<tr>
<td>Department:</td> <td><form:input path="department.name"/></td>
</tr>
<tr>
<td><input type="submit"></td>
</tr>
</table>
</form:form>
Dao层里的代码
@Autowired
private SessionFactory sessionFactory;
private Session getSession(){
return sessionFactory.getCurrentSession();
}
public void add(User user) {
Session session = getSession();
session.save(user);
}
结果数据库更新后是这样的
执行的SQL
Hibernate: insert into Department (name) values (?)
Hibernate: insert into User (age, department_id, name) values (?, ?, ?)
想要达到的效果是新增User的department_id应该还是已有的部门，而不是新建一个部门。请问是什么问题啊。
多谢了！！！
