Question

我有一个用户表，以及一个用户之间的通话表。

public class User {

    @Id
    @Column(name="userId")
    private long userId;

    @OneToMany(mappedBy="caller")
    Set<Call> madeCalls;

    @OneToMany(mappedBy="callee")
    Set<Call> receivedCalls;

}

public class Call {

    @ManyToOne
    @JoinColumn(name="calleeId", referencedColumnName="userId")
    User callee;

    @ManyToOne
    @JoinColumn(name="callerId", referencedColumnName="userId")
    User caller;

}

为简洁起见，省略了诸如getter和setter的详细信息以及其他字段（标识等）。

每个呼叫涉及一个呼叫者和一个被呼叫者。每个用户可以拨打和接听许多电话。

简单地说：上面的JPA有效使用方法是，特别是休眠吗？

Answer 1

没有主键就不能拥有休眠类。此外，您应该使用property-based acccess而不是field-based access，否则休眠将给您带来编译时错误。您的代码应为：

@Entity
@Table(name="user")
public class User {

    @Id // use all these annotation in  the getter method
    @GeneratedValue(strategy = GenerationType.AUTO, generator = "native")
    @GenericGenerator(name = "native", strategy = "native")
    private long userId;

    @OneToMany(mappedBy="caller") // use this annotation in  the getter method
    private Set<Call> madeCalls;

    @OneToMany(mappedBy="callee") // use this annotation in  the getter method
    private Set<Call> receivedCalls;

}

@Entity
@Table(name="call")
public class Call {

    @Id // use all these annotation in  the getter method
    @GeneratedValue(strategy = GenerationType.AUTO, generator = "native")
    @GenericGenerator(name = "native", strategy = "native")
    private long callId;

    @ManyToOne
    @JoinColumn(name="calleeId") // use this annotation in  the getter method
    private User callee;

    @ManyToOne
    @JoinColumn(name="callerId") // use this annotation in  the getter method
    private User caller;

}

Here is a very good tutorial for hibernate and performance。

Hibernate中两个OneToMany设置为同一表

1 个答案: