1
user.java
@Entity
@Table(name="user")
public class user
{
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
private int uid;
@OneToMany(cascade = CascadeType.ALL, fetch = FetchType.LAZY, mappedBy ="user")
private Set<order> orders = new HashSet<order>();
//
setter ,getter ,and other
}
order.java
@Entity
@Table(name="`order`")
public class order
{
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
private int oid;
@OneToMany(cascade = CascadeType.ALL)
@JoinColumn(name="oid", referencedColumnName="oid")
private Set<orderitem> orderitems = new HashSet<orderitem>();
@ManyToOne(cascade=CascadeType.ALL)
@JoinColumn(name="uid")
private user user ;
/////
setter ,getter and other
}
orderitem.java
@Entity
@Table(name="orderitem")
public class orderitem
{
@EmbeddedId
private orderitem_PK PK; //composite key
@ManyToOne
@JoinColumn(name="oid", referencedColumnName="oid" ,insertable = false, updatable = false)
private order order;
@ManyToOne
@JoinColumn(name="pid", referencedColumnName="pid", insertable = false, updatable = false)
private product products ;
////
setter,getter and other
}
orderitem_PK。 java
@Embeddable
public class orderitem_PK implements Serializable
{
private int oid;
private int pid;
public orderitem_PK() {}
public orderitem_PK(int oid, int pid) {
this.oid = oid;
this.pid = pid;
}
// equals, hashCode
@Override
public boolean equals(Object obj) {
// TODO Auto-generated method stub
return super.equals(obj);
}
@Override
public int hashCode() {
// TODO Auto-generated method stub
return super.hashCode();
}
和最后product.java
@Entity
@Table(name="product")
public class product
{
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
private int pid;
@OneToMany(cascade = CascadeType.ALL)
@JoinColumn(name="pid", referencedColumnName="pid")
private Set<orderitem> orderitems = new HashSet<orderitem>();
//////////
setter,getter and other
}
它是一个网上购物页面
我想这段代码
order order = new order();
order.setUser(user);
order.setOrdertotal(product.getPrice());
Date dt = new Date();
DateFormat df = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
String nowTime = df.format(dt);
java.sql.Timestamp buydate = java.sql.Timestamp.valueOf(nowTime);
order.setOrderdate(buydate);
/// delete this part will work
orderitem orderitem = new orderitem();
orderitem.setOrder(order);
orderitem.setProducts(product);
orderitem.setQuantity(product.getQuantity());
orderitem.setPrice(product.getPrice());
////
session.save(order);
session.save(orderitem);
遇到一些错误插入的数据。
org.hibernate.id.IdentifierGenerationException:用于生成空ID:类Model.orderitem
时,我只保存用户和订单部分的代码工作。
添加保存orderitem代码后,发生问题。
我认为复合键映射外键是错误的。
但我不知道如何解决它。
任何人都可以发现我做错了什么吗?
谢谢。
谢谢,但我尝试用自己的方式,仍然occurre问题“无法设置字段值[9]通过反射值:类Model.orderitem_PK.oid] Model.orderitem_PK.oid的二传手”和值]会累积每次我尝试,这很奇怪 – alan14alan
如果你想使用@MapsId设置这些字段,你需要在orderitem_PK中拥有oid和pid的getter和setter。 – shubham
我确实在getitem_PK中有getter和setter。我忘了说它 – alan14alan