我定义了一个非常简单的数据库，如下所示：
我正在使用hibernate 插件来生成不同的类，包括客户和订单之间的一对多关系。我将此关系作为识别关系，因为如果不链接到客户，订单就无法存在。
我有以下三个课程：
=> 类客户
private int idCustomer;
private String name;
private Set<Order> orders = new HashSet<Order>(0);
public Customer() {
}
public Customer(int idCustomer) {
this.idCustomer = idCustomer;
}
public Customer(int idCustomer, String name, Set<Order> orders) {
this.idCustomer = idCustomer;
this.name = name;
this.orders = orders;
}
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
@Column(name = "idCustomer", unique = true, nullable = false)
public int getIdCustomer() {
return this.idCustomer;
}
public void setIdCustomer(int idCustomer) {
this.idCustomer = idCustomer;
}
@Column(name = "name", length = 45)
public String getName() {
return this.name;
}
public void setName(String name) {
this.name = name;
}
@OneToMany(fetch = FetchType.LAZY, mappedBy = "customer")
public Set<Order> getOrders() {
return this.orders;
}
public void setOrders(Set<Order> orders) {
this.orders = orders;
}
=> 班级顺序：
private OrderId id;
private Customer customer;
private String quantity;
private Float price;
public Order() {
}
public Order(OrderId id, Customer customer) {
this.id = id;
this.customer = customer;
}
public Order(OrderId id, Customer customer, String quantity, Float price) {
this.id = id;
this.customer = customer;
this.quantity = quantity;
this.price = price;
}
@EmbeddedId
@AttributeOverrides({
@AttributeOverride(name = "idOrder", column = @Column(name = "idOrder", nullable = false)),
@AttributeOverride(name = "customerIdCustomer", column = @Column(name = "Customer_idCustomer", nullable = false)) })
public OrderId getId() {
return this.id;
}
public void setId(OrderId id) {
this.id = id;
}
@ManyToOne(fetch = FetchType.LAZY)
@JoinColumn(name = "Customer_idCustomer", nullable = false, insertable = false, updatable = false)
public Customer getCustomer() {
return this.customer;
}
public void setCustomer(Customer customer) {
this.customer = customer;
}
@Column(name = "quantity", length = 45)
public String getQuantity() {
return this.quantity;
}
public void setQuantity(String quantity) {
this.quantity = quantity;
}
@Column(name = "price", precision = 12, scale = 0)
public Float getPrice() {
return this.price;
}
public void setPrice(Float price) {
this.price = price;
}
=> 类 OrderId
private int idOrder;
private int customerIdCustomer;
public OrderId() {
}
public OrderId(int idOrder, int customerIdCustomer) {
this.idOrder = idOrder;
this.customerIdCustomer = customerIdCustomer;
}
@Column(name = "idOrder", nullable = false)
public int getIdOrder() {
return this.idOrder;
}
public void setIdOrder(int idOrder) {
this.idOrder = idOrder;
}
@Column(name = "Customer_idCustomer", nullable = false)
public int getCustomerIdCustomer() {
return this.customerIdCustomer;
}
public void setCustomerIdCustomer(int customerIdCustomer) {
this.customerIdCustomer = customerIdCustomer;
}
public boolean equals(Object other) {
if ((this == other))
return true;
if ((other == null))
return false;
if (!(other instanceof OrderId))
return false;
OrderId castOther = (OrderId) other;
return (this.getIdOrder() == castOther.getIdOrder())
&& (this.getCustomerIdCustomer() == castOther
.getCustomerIdCustomer());
}
public int hashCode() {
int result = 17;
result = 37 * result + this.getIdOrder();
result = 37 * result + this.getCustomerIdCustomer();
return result;
}
然后我有我的主要课程：
public static void main(String[] args) {
Customer customer = new Customer();
customer.setName("John Doe");
CustomerDAO.save(customer);
Order order = new Order();
order.setQuantity(10);
order.setPrice(100);
order.setCustomer(customer);
OrderDAO.save(order);
}
请注意，我的 DAO 对象没有做任何花哨的事情......只是获取会话的常用 HibernateUtil 实现，最后调用“保存”方法。我的问题如下。我以前从未处理过复合键...请原谅我的愚蠢问题。我不想手动处理不同的 id 和主键。对于 Cutomer 类，这不是问题，因为我设置了一个策略，在保存到数据库时会自动创建 id。对于 Order 类，我也不想处理这个问题。但是由于密钥是复合的，Hibernate 在尝试将此对象保存在 DB 中时会生成一个 identifierGenerationExeption ...我想要的是以下 => 自动生成的订单 ID，因为我在订单对象中设置了客户，
谢谢