Spring JPA 如何创建表以便我可以共享公共 ID？

Question

我想在 Spring 中创建消息系统。我将有 3 个模型和 2 个表格。我想做的是：
1）创建一个表“对话”=完成
2）在表“对话”中创建新条目，其中包含对话 ID 和对话主题 = 完成。
4）创建新表“conversations_members”
5）在表“conversations_members”中创建两个新条目，一个为conversation_id、sender_id、lastviewed date、isdeleted = 0 (false) 和conversation_id、receiver_id、lastviewed_date、isdeleted=0(false)
6）我下一个表格，回复我想在“conversations_messages”中生成带有 message_id（自动生成，长 id）、conversation_id、message_date 和 message_text 的条目。

我不知道如何在 3 个表中连接所有 conversation_id。我认为这将是“一对多”选项，但如何使用它呢？ 最好的问候，Jędrzej。

对话模型：

@Entity
@Table(name = "conversation")
public class Conversation {

@Id
@Column(name = "conversation_id")
@GeneratedValue(strategy = GenerationType.AUTO)
private Long id;

@Column(name = "conversation_subject")
private String subject;

public Long getId() {
    return id;
}

public void setId(Long id) {
    this.id = id;
}

public String getSubject() {
    return subject;
}

public void setSubject(String subject) {
    this.subject = subject;
}

public Conversation(String subject) {
    this.subject = subject;
}

public Conversation() {

}

}

ConversationMembers 模型：

@Entity
@Table(name="conversation_members")
public class ConversationMembers {

@Column(name="conversation_id")
private Conversation conversation;


@Column(name="user_id")
private SiteUser user;

@Column(name="conversation_deleted",  columnDefinition="Integer(0,1) default '0'")
private int conversationDeleted;


@Column(name="column_last_viewed")
private Date date;


public Conversation getConversation() {
    return conversation;
}


public void setConversation(Conversation conversation) {
    this.conversation = conversation;
}


public SiteUser getUser() {
    return user;
}


public void setUser(SiteUser user) {
    this.user = user;
}


public int getConversationDeleted() {
    return conversationDeleted;
}


public void setConversationDeleted(int conversationDeleted) {
    this.conversationDeleted = conversationDeleted;
}


public Date getDate() {
    return date;
}


public void setDate(Date date) {
    this.date = date;
}


public ConversationMembers(Conversation conversation, SiteUser user, int    conversationDeleted, Date date) {
    this.conversation = conversation;
    this.user = user;
    this.conversationDeleted = conversationDeleted;
    this.date = date;
}
}

ConversationMessage 模型：

@Entity
@Table(name="conversations_messages")
public class ConversationMessages {
@Id
@GeneratedValue(strategy = GenerationType.AUTO)
@Column(name="message_id")
private Long messsageId;

@Column(name="conversation_id")
private Conversation conversation;

@Column(name="message_date")
private Date message_date;

@Column(name="message_text")
private String text;

public Long getMesssageId() {
    return messsageId;
}

public void setMesssageId(Long messsageId) {
    this.messsageId = messsageId;
}

public Conversation getConversation() {
    return conversation;
}

public void setConversation(Conversation conversation) {
    this.conversation = conversation;
}

public Date getMessage_date() {
    return message_date;
}

public void setMessage_date(Date message_date) {
    this.message_date = message_date;
}

public String getText() {
    return text;
}

public void setText(String text) {
    this.text = text;
}

public ConversationMessages(Long messsageId, Conversation conversation, Date   message_date, String text) {
    this.messsageId = messsageId;
    this.conversation = conversation;
    this.message_date = message_date;
    this.text = text;
}
}

NewConversation.jsp

<form:form commandName="conversation">
<br>

<form:form commandName="conversationmembers">
To:
<form:input path="userid" type="text" name="userid" />
SUBJECT
<form:input path="subject" type="text" name="subject" />
    <button type="submit" value="start conversation" />

</form:form>
</form:form>

Answer 1

根据你的问题，我知道你想建立关系。所以你可以使用类似的东西

对话

@Entity @Table(name = "conversation") public class Conversation {

@Id
@Column(name = "conversation_id")
@GeneratedValue(strategy = GenerationType.AUTO)
private Long id;

@Column(name = "conversation_subject")
private String subject;

@OnetoMany(fetch=FetchType.LAZY,cascade=CascadeType.MERGE)
private List<ConverstaionMessage> message;

@OnetoMany(fetch=FetchType.LAZY,cascade=CascadeType.MERGE)
private List<ConverstaionModel> message;

// getter setter 以此类推

public Long getId() {
    return id;
}

public void setId(Long id) {
    this.id = id;
}

public String getSubject() {
    return subject;
}

public void setSubject(String subject) {
    this.subject = subject;
}

public Conversation(String subject) {
    this.subject = subject;
}

public Conversation() {

}

}

你也可以使用 ConversationMessage 和 ConversationModel 中的@ManyToOne