可嵌入/ManyToOne/OneToMany 不工作

Question

我很了解 Java，目前我正在开发 ChatProgramm。因此，我想使用注入创建一个 table 消息，其中嵌入了我的 table 联系人的 ID (USERNUMBER)。这是我的消息的 class:

@Embeddable
@Entity(name = "MESSAGE")
public class Message implements Serializable {


@ManyToOne
@GeneratedValue(strategy = GenerationType.AUTO)
@Column(name = "INCOME_MESSANGE", nullable = false)
private String incomingMessage;

@EmbeddedId
@JoinColumn(name = "USERNUMBER", nullable = false)
private Contact contact;
ChatApplicationRemote chatApplicationRemote;

public Message(String ip, String msg) throws IOException {
    incomingMessage = msg;
    contact = chatApplicationRemote.getcontactByIP(ip.toString());
}

public Message(){

}

public String getIncomingMessage() {
    return incomingMessage;
}

public Contact getContact() {
    return contact;
}

这是我的联系人：

@Entity(name = "CONTACTS")
@Embeddable
public class Contact implements Serializable {

/**
 * 
 */
private static final long serialVersionUID = -6855140755056337926L;
@Column(name = "NAME", nullable = false)
private String name;
@Column(name = "PRENAME", nullable = false)
private String vorname;
@Column(name = "IP", nullable = false)
private String ip;
@Column(name = "PORT", nullable = false)
private Integer port;
@Id
@OneToMany(mappedBy = "Message.incomingMessage")
@Column(name = "USERNUMBER", nullable = false)
private String usernumber;

public Contact(String usernumber, String name, String vorname, String ip, String port) {
    super();
    this.usernumber = usernumber;
    this.name = name;
    this.vorname = vorname;
    this.ip = ip;
    this.port = Integer.parseInt(port);
}

public Contact(){

}

public String getUsernumber() {
    return usernumber;
}

//......

因此，在我的消息中，出现了两个错误： @ManyToOne 抛出：目标实体 "java.lang.String" 不是实体 @EmbeddedID 抛出：de.nts.data.Contact 未映射为可嵌入的

所以我用谷歌搜索了一段时间.. 发现了一些我没有的关于 orm.xml 的东西。即使我创建了一个，@EmbeddedID throws:Embedded ID class 也应该包括 equals() 和 hashcode() 的方法定义，并且 orm.xml 属性 "usernumber" 中的映射类型无效这个语境。

有人可以帮忙吗？

Answer 1

尝试

@Entity
public class Message implements Serializable {
  @Id
  @GeneratedValue(strategy=GenerationType.AUTO)
  private Long id;

  @Column(name = "INCOME_MESSANGE", nullable = false)
  private String incomingMessage;

  @ManyToOne
  @JoinColumn(name = "USERNUMBER", nullable = false)
  private Contact contact;

  @Transient
  ChatApplicationRemote chatApplicationRemote;
  ..
}


@Entity
public class Contact implements Serializable {

  private static final long serialVersionUID = -6855140755056337926L;

  @Column(name = "NAME", nullable = false)
  private String name;
  @Column(name = "PRENAME", nullable = false)
  private String vorname;
  @Column(name = "IP", nullable = false)
  private String ip;
  @Column(name = "PORT", nullable = false)
  private Integer port;
  @Id
  @Column(name = "USERNUMBER", nullable = false)
  private String usernumber;

  @OneToMany(mappedBy = "incomingMessage")
  private LIst<Message> messages;
  ..
}

也许可以作为一个起点，但正如 JB Nizet 所建议的那样，从一些简单的 JPA/Java 演示开始，先获得基础知识并进行构建。您的示例比异常显示的错误更多，none 只需抛出 ORM.xml.

即可解决

可嵌入/ManyToOne/OneToMany 不工作

Embeddable/ ManyToOne/ OneToMany not working

java

jpa

persistence