初学者：定义JPA一对一映射时出错

Question

我有以下表格：

Login -> (id, username, password)
Members -> (member_id, name, address)

id与具有一对一映射的成员_id相关。

我写了两个模型作为例子

html" target="_blank">登录模式：

@Entity
@Table(name = "Login", uniqueConstraints = { @UniqueConstraint(columnNames = "username") })
public class Login {

private int id;
private String username;
private String password;
private Members members;

@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
@Column(name = "id")
public int getId() {
    return id;
}

@OneToOne(fetch = FetchType.LAZY, cascade = CascadeType.ALL, optional = true)
@JoinColumn(name = "id", referencedColumnName = "member_id")
public Members getMembers() {a
    return members;
}

}

Memeber模型：

@Entity
@Table(name = "Members")
public class Members {
private int member_id;
private String name;
private String address;

@Id
@GeneratedValue(generator = "gen")
@GenericGenerator(name = "gen", strategy = "foreign", parameters = { @Parameter(name = "property", value = "Login") })
@Column(name = "member_id")
public int getMember_id() {
    return member_id;
}

private Login login;

@OneToOne(fetch = FetchType.LAZY, optional = true, cascade = CascadeType.ALL)
public Login getLogin() {
    return login;
}

}

为了简单起见，我放弃了一些getter和setter。不管怎样，你能告诉我哪里出了问题吗？在更改注释值时，我会遇到诸如映射未找到、持久类未知等错误。

错误

org.springframework.web.util.NestedServletExc0019：请求处理失败；嵌套异常是org.springframework.beans.factory.BeanCreationExc0019：错误创建在类路径资源[数据库/Hibernate.xml]中定义的名称'会话工厂'的bean：调用init方法失败；嵌套异常是org.hibernate.注释异常：@OneToOne或@ManyToOneorg.sparsham.login.model.Login.members引用未知实体：org.sparsham.members.model.成员org.springframework.web.servlet.FrameworkServlet.process请求（FrameworkServlet.java:894）org.springframework.web.servlet.FrameworkServlet.do获取（FrameworkServlet.java:778）javax.servlet.http.HttpServlet.service（HttpServlet.java:621）javax.servlet.http.HttpServlet.service（HttpServlet.java:722）

Answer 1

希望这能解决你最后的问题。试试这些改变。

登录模式：

@OneToOne(fetch = FetchType.LAZY, cascade = CascadeType.ALL, optional = true)
@PrimaryKeyJoinColumn
public Members getMembers() {a
    return members;
}

成员模式：

@Id
@GeneratedValue(generator = "gen")
@GenericGenerator(name = "gen", strategy = "foreign", parameters = { @Parameter(name =          "property", value = "login") })
@Column(name = "member_id")
public int getMember_id() {
    return member_id;
}

private Login login;

@OneToOne(fetch = FetchType.LAZY, optional = true, cascade = CascadeType.ALL, mappedBy="members")
@PrimaryKeyJoinColumn
public Login getLogin() {
    return login;
}

请注意@GenericGenerator注释中的@Parameter部分，“登录”可能是区分大小写的。