当我尝试在简单的 DataGrid 中加载“产品”列表时出现此错误：
Didn't receive an acknowledge message
Was expecting mx.messaging.messages.AcknowledgeMessage, but received null
经过几次测试，我现在很确定这是一个映射问题，而且我不习惯注释，也许它来自这里，这里是我的类：
产品.java：
@Entity
@Table(name="product")
public class Product implements Serializable
{
@Id
@GeneratedValue(strategy = GenerationType.AUTO)
@Column(name="product_id")
private long productId;
private String name;
@ManyToOne(optional = false, fetch = FetchType.EAGER)
@JoinColumn(name="category_id")
private Category category;
@OneToMany(mappedBy = "product", cascade = CascadeType.ALL, fetch = FetchType.LAZY)
private Collection<Buy> clients;
...Getters & Setters...
}
客户端.java
@Entity
@Table(name="client")
public class Client implements Serializable {
@Id
@GeneratedValue(strategy = GenerationType.AUTO)
@Column(name="client_id")
private long clientId;
private String name;
@OneToMany(mappedBy = "client", cascade = CascadeType.ALL, fetch = FetchType.LAZY)
private Collection<Buy> products;
public long getClientId() {
return clientId;
}
public void setClientId(long clientId) {
this.clientId = clientId;
}
...Getters & Setters...
}
购买.java
@Entity
@Table(name="buy")
public class Buy implements Serializable
{
@EmbeddedId
private BuyId buyId;
@ManyToOne
@PrimaryKeyJoinColumn(name="product_id", referencedColumnName="product_id")
private Product product;
@ManyToOne
@PrimaryKeyJoinColumn(name="client_id", referencedColumnName="client_id")
private Client client;
@Temporal(value = TemporalType.DATE)
private Date date;
...Getters & Setters...
}
BuyId.java
public class BuyId implements Serializable
{
private long clientId;
private long productId;
...Getters & Setters...
}
类别无关紧要，因为只有一个 Id 和一个名称，产品和类别之间的关联是单向的，真正的问题是当我尝试从数据库中检索我的产品时，会发生此错误，正如我所说，我几乎肯定它来自映射/注释错误......
谢谢。