Question

我有一个实体“ Task”，它需要一个名为“ timestamps”的内部组件，该组件保存有关该任务的提交，启动和完成时间的值。

@Entity
public class Task {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Integer Id;
    private String Status;
    private Timestamps timestamps;
    // getters setters
}

然后我创建了Timestamps类

public class Timestamps {
 private Timestamp submitted;
 private Timestamp started;
 private Timestamp completed;
 //getter and setters
}

如何进行此映射，以便在以JSON格式检索信息时出现类似这样的内容？

# task
{
    "task": # ASCII string
    "status": # one of "submitted", "started", "completed"
    "timestamps": {
    "submitted": # unix/epoch time
    "started": # unix/epoch time or null if not started
    "completed": # unix/epoch time or null if not completed
    }
}

Answer 1

如果您不想将Timestamps保留在数据库中而只在DTO中使用它，这将为您提供帮助：

@Transient批注用于指示字段不会保留在数据库中。

@Entity
public class Task {
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
private Integer Id;
private String Status;
@Transient
private Timestamps timestamps;
// getters setters
}

如果您想将Timestamps保留为一种关系，则应执行以下操作：

@Entity
public class Timestamps {
 @Id
 @GeneratedValue(strategy = GenerationType.IDENTITY)
 private Integer Id;
 private Timestamp submitted;
 private Timestamp started;
 private Timestamp completed;
 //getter and setters
}

@Entity
public class Task {
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
private Integer Id;
private String Status;
@ManyToOne
private Timestamps timestamps;
// getters setters
}

Answer 2

您可以将@Embeddable注释放在时间戳上。 Hibernate将字段映射为同一表中的列。您可能还需要在Task中的“时间戳”字段上添加一个@Embedded（如果双方都需要注释，则我无法确定）。

休眠映射内部类，错误“无法确定类型：timeStamps”

2 个答案: