复合外键映射hibernate实体

Question

我在MySQL数据库中有三个表 1.使用主键的表用户：用户名。
2.具有主键的表顺序：orderid和外键：username（参考表用户的用户名）
3.表orderdetail与主键：id和复合外键：orderid;用户名（请参阅订单中的orderid和用户名。）

现在如何为Table ordersDetail设置Entity类OrderDetail，让hibernate正常工作。

//订单类

@Entity
@Table(name="orders")
public class Order {

@Id
private long orderid;
private double price;   
private String status;  
@ManyToOne
@JoinColumn(name="username")
private User user;

//Constructor take 0 args and 4 args.
public Order() {
    this.user = new User();
}

public Order(long orderid, double price, String status, User user) {
    this.orderid = orderid;
    this.price = price;
    this.status = status;
    this.user = user;
}


@Embeddable
class CompositeKey implements Serializable {

private static final long serialVersionUID = -8711530222180590954L;

public String username;
public long orderid;

}

// OrderDetail Class

@Entity
@Table(name = "ordersdetail")
public class OrderDetail implements Serializable{

private static final long serialVersionUID = -3936223721422733989L;
@Id
@GeneratedValue
private int id;
private int quantity;
private Order order;

@ManyToOne
@JoinColumn(name = "goodsid")
private Goods goods;

@ManyToOne
@JoinColumns({
        @JoinColumn(name = "username", referencedColumnName = "username"),
        @JoinColumn(name = "orderid", referencedColumnName = "orderid") })
private CompositeKey key;

public CompositeKey getKey() {
    return key;
}

public void setKey(CompositeKey key) {
    this.key = key;
}