Hibernate注释一对多关系返回null

Question

Al Salam Alaykom，

我正在尝试在设备和位置类之间的一对多关系中使用hibernate注释，一个设备有许多位置。我在选择设备时得到一个空位列表的问题，我尝试了很多解决方案而没有解决问题

这是我班级中的关系部分：

Device.java

@GwtTransient
private List<Position> positions = new LinkedList<Position>();

@OneToMany(mappedBy="device")
public List<Position> getPositions() {
    return positions;
}


public void setPositions(List<Position> positions) {
    this.positions = positions;
}

@GwtTransient private List<Position> positions = new LinkedList<Position>(); @OneToMany(mappedBy="device") public List<Position> getPositions() { return positions; } public void setPositions(List<Position> positions) { this.positions = positions; }

和Position.java

private Device device;

@ManyToOne(fetch = FetchType.EAGER)
@JoinColumn(name = "device_id")
public Device getDevice() {
    return device;
}
public void setDevice(Device device) {
    this.device = device;
}

另外，我尝试了以下注释：

private Device device; @ManyToOne(fetch = FetchType.EAGER) @JoinColumn(name = "device_id") public Device getDevice() { return device; } public void setDevice(Device device) { this.device = device; }

    / ******************* ************** /

//In Device:
@OneToMany(mappedBy = "device")
@LazyCollection(LazyCollectionOption.FALSE)

//In Position:
@ManyToOne(fetch = FetchType.LAZY)
@JoinColumns({@JoinColumn(name = "device_id", insertable=false, updatable=false)})

//In Device: @OneToMany(mappedBy = "device") @LazyCollection(LazyCollectionOption.FALSE) //In Position: @ManyToOne(fetch = FetchType.LAZY) @JoinColumns({@JoinColumn(name = "device_id", insertable=false, updatable=false)})

    / ******************* ************** /

//In Device:
@OneToMany(mappedBy = "device",fetch = FetchType.EAGER)
@LazyCollection(LazyCollectionOption.FALSE)
@Fetch(FetchMode.SELECT)    

//In Position:
@ManyToOne
@JoinColumn (name="device_id")

//In Device: @OneToMany(mappedBy = "device",fetch = FetchType.EAGER) @LazyCollection(LazyCollectionOption.FALSE) @Fetch(FetchMode.SELECT) //In Position: @ManyToOne @JoinColumn (name="device_id")     / ******************* ************** /     

//In Device:
@OneToMany(mappedBy = "device")
@LazyCollection(LazyCollectionOption.FALSE)

//In Position:
@ManyToOne
@PrimaryKeyJoinColumn

任何帮助将不胜感激......谢谢