我收到了异常的例外情况,但无法追查其原因。请帮帮我。
我只是使用OneToOne映射和PrimarykeyJoinColumn属性。
@Entity
@Table(name="mediashow_user1")
public class UserVO implements Serializable{
private static final long serialVersionUID = 6066636545309839156L;
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
private Long empid ;
private String email = null;
private String fname = null ;
private String lname = null ;
private String mname = null ;
private String uname = null ;
private String passwd = null ;
private String serctquestion = null ;
private String serctanswer = null ;
private int telephone;
private Timestamp cur_timestamp = null ;
private Timestamp lastvisited_timestamp = null ;
@OneToOne(cascade=CascadeType.ALL)
@PrimaryKeyJoinColumn
private AddressVO addressVO;
@Column(name="empid")
public Long getEmpid() {
return empid;
}
..................
另一个AddressVO.java
@Entity
@Table(name="mediashow_address1")
@GenericGenerator(name="foreign", strategy = "foreign", parameters={
@Parameter(name="property", value="userVO")
})
public class AddressVO implements Serializable {
private static final long serialVersionUID = -96886746528894662L;
@Id
@GeneratedValue(generator="foreign")
private Long empid;
private String street = null ;
private String zipcode = null ;
private String landmark = null ;
........
}
Transaction transaction = null;
try {
transaction = session.beginTransaction();
AnnotationConfiguration conf = (new AnnotationConfiguration()).configure();
new SchemaExport(conf).create(true, false);
UserVO user = new UserVO();
user.setEmail("abc@gmail.com");
user.setFname("Rahul10");
user.setMname("Bapusaheb10");
user.setLname("Bandgar10");
user.setUname("rahul");
user.setPasswd("rahul");
user.setSerctanswer("baramati");
user.setSerctquestion("What is your birth place name?");
AddressVO address = new AddressVO();
address.setLandmark("Landmark5");
address.setStreet("street4");
address.setZipcode("234344");
int i = 9850;
user.setTelephone(i);
user.setAddressVO(address);
Long id= (Long)session.save(user);
System.out.println("ID::"+id);
transaction.commit();
} catch (HibernateException e) {
System.out.println("Exception:"+e.getMessage());
transaction.rollback();
e.printStackTrace();
} finally {
session.close();
}
我在运行上面的代码时遇到异常。
alter table mediashow_user1 下降 外键FK5FD5BCE8801495D
drop table if exists mediashow_address1
drop table if exists mediashow_user1
create table mediashow_address1 (
empid bigint not null,
landmark varchar(255),
street varchar(255),
zipcode varchar(255),
primary key (empid)
)
create table mediashow_user1 (
empid bigint not null auto_increment,
cur_timestamp datetime,
email varchar(255),
fname varchar(255),
lastvisited_timestamp datetime,
lname varchar(255),
mname varchar(255),
passwd varchar(255),
serctanswer varchar(255),
serctquestion varchar(255),
telephone integer not null,
uname varchar(255),
primary key (empid)
)
alter table mediashow_user1
add index FK5FD5BCE8801495D (empid),
add constraint FK5FD5BCE8801495D
foreign key (empid)
references mediashow_address1 (empid)
Exception in thread "main" java.lang.NullPointerException
at org.hibernate.tuple.entity.AbstractEntityTuplizer.getPropertyValue(AbstractEntityTuplizer.java:521)
at org.hibernate.persister.entity.AbstractEntityPersister.getPropertyValue(AbstractEntityPersister.java:3867)
at org.hibernate.id.ForeignGenerator.generate(ForeignGenerator.java:100)
at org.hibernate.event.def.AbstractSaveEventListener.saveWithGeneratedId(AbstractSaveEventListener.java:121)
at org.hibernate.event.def.DefaultSaveOrUpdateEventListener.saveWithGeneratedOrRequestedId(DefaultSaveOrUpdateEventListener.java:210)
at org.hibernate.event.def.DefaultSaveOrUpdateEventListener.entityIsTransient(DefaultSaveOrUpdateEventListener.java:195)
at org.hibernate.event.def.DefaultSaveOrUpdateEventListener.performSaveOrUpdate(DefaultSaveOrUpdateEventListener.java:117)
at org.hibernate.event.def.DefaultSaveOrUpdateEventListener.onSaveOrUpdate(DefaultSaveOrUpdateEventListener.java:93)
at org.hibernate.impl.SessionImpl.fireSaveOrUpdate(SessionImpl.java:685)
at org.hibernate.impl.SessionImpl.saveOrUpdate(SessionImpl.java:677)
at org.hibernate.engine.CascadingAction$5.cascade(CascadingAction.java:252)
at org.hibernate.engine.Cascade.cascadeToOne(Cascade.java:392)
at org.hibernate.engine.Cascade.cascadeAssociation(Cascade.java:335)
at org.hibernate.engine.Cascade.cascadeProperty(Cascade.java:204)
at org.hibernate.engine.Cascade.cascade(Cascade.java:161)
at org.hibernate.event.def.AbstractSaveEventListener.cascadeBeforeSave(AbstractSaveEventListener.java:450)
at org.hibernate.event.def.AbstractSaveEventListener.performSaveOrReplicate(AbstractSaveEventListener.java:282)
at org.hibernate.event.def.AbstractSaveEventListener.performSave(AbstractSaveEventListener.java:203)
at org.hibernate.event.def.AbstractSaveEventListener.saveWithGeneratedId(AbstractSaveEventListener.java:129)
at org.hibernate.event.def.DefaultSaveOrUpdateEventListener.saveWithGeneratedOrRequestedId(DefaultSaveOrUpdateEventListener.java:210)
at org.hibernate.event.def.DefaultSaveEventListener.saveWithGeneratedOrRequestedId(DefaultSaveEventListener.java:56)
at org.hibernate.event.def.DefaultSaveOrUpdateEventListener.entityIsTransient(DefaultSaveOrUpdateEventListener.java:195)
at org.hibernate.event.def.DefaultSaveEventListener.performSaveOrUpdate(DefaultSaveEventListener.java:50)
at org.hibernate.event.def.DefaultSaveOrUpdateEventListener.onSaveOrUpdate(DefaultSaveOrUpdateEventListener.java:93)
at org.hibernate.impl.SessionImpl.fireSave(SessionImpl.java:713)
at org.hibernate.impl.SessionImpl.save(SessionImpl.java:701)
at org.hibernate.impl.SessionImpl.save(SessionImpl.java:697)
at com.imgshop.run.TestAddIntoLogin.main(TestAddIntoLogin.java:49)
答案 0 :(得分:5)
我遇到了类似的情况,经过一些实验后自己解决了。这里要记住的一件重要事情是,当您对ID生成器使用foreign
策略时,关系不能是单向的。在您的情况下,您需要进行两处更改(见下文)。基本上,您已为AddressVO @OneToOne(cascade=CascadeType.ALL)
设置了全部级联,当您尝试保存UserVO时,这将触发AddressVO的类似操作。但是对于AddressVO,您将Id生成器策略设置为具有属性userVO
的“外部”。但是你永远不会在AddressVO中设置属性userVO
,因此它会获得null id,因此也会出现异常。为此,您需要进行以下更改
1)将userVO属性(getter / setters)添加到AddressVo,然后在保存userVo之前将此对象添加到事务address.setUserVo(user);
中的addressVO,然后调用session.save(user);
2)编辑db模式以反映addressVO中的共享主键,因为外键约束在AddressVo中而不在UserVO中。即,更改以下
alter table mediashow_user1
add index FK5FD5BCE8801495D (empid),
add constraint FK5FD5BCE8801495D
foreign key (empid)
references mediashow_address1 (empid)
到
alter table mediashow_address1
add index FK5FD5BCE8801495D (empid),
add constraint FK5FD5BCE8801495D
foreign key (empid)
references mediashow_user1 (empid)
如果您希望将此功能用于 Unidirection 一对一关系,那么您应该自己处理级联操作。基本上你应该做以下
1)删除外键策略(只需在AddressVO中为empId使用@Id和@column注释,不带任何@GeneratedValue)。
2)在UserVO中删除AddressVo的级联选项(因为这将触发AddressVO上的类似操作并且id仍然未知)
3)在保存此地址之前,为AddressVo设置empId。您应该使用保存userVo时获得的ID。
Long id= (Long)session.save(user);
address.setEmpid(id);
session.save(address)
基本上你应该处理地址的保存/更新/删除操作。
希望这个解释有助于:)
答案 1 :(得分:0)
在代码中进行此更改:
@GenericGenerator(name="foreign", strategy = "foreign", parameters={
@Parameter(name="property", value="user")
})
我们需要在value参数的参数注释中传递类的对象而不是类名。 因此,不应该有value =“userVO”,而应该是value =“user”
请尝试让我知道它是否有效