休眠-如何保持一对多的“后退”

Question

I have an interesting situation. I'm working on a game. I have a board with a 2d array of object 'Space'. Each 'Space' has four references to object 'Boundary' (north, east, south, west).

A space shares a reference to 'Boundary'. For example 'Space' at location (0,0) shares its east boundary with the west boundary of 'Space' at location (1,0). This allows me to only update the boundary once when something happens (like from wall to none if the was is destroyed).

Any idea how to persist something like this using Hibernate? I really have a 1-to-many with boundary having many spaces, but I'm not sure how to relate them specifically back to a specific boundary (north,south,west,east). I also don't know how to set this up so that the two 'Space' object share a reference to the single boundary object.

public class Space {
  private Boundary northBoundry;
  private Boundary eastBoundry;
  private Boundary southBoundry;
  private Boundary westBoundry;

  //hero on the Space
  private HeroBase hero;

  private long     spaceId;

  //getters and setters
}

public class Boundary {

  public static final String NONE        = "none";
  public static final String CLOSED_DOOR = "closed_door";
  public static final String OPEN_DOOR   = "open_door";
  public static final String WALL        = "wall";

  private String             type;
  long                       boundaryId;

  //getters and setters
}

Answer 1

What you describe is a many-to-one relation between Space and each Boundary :

public class Space {
  @ManyToOne
  @JoinColumn(name="NORTH_BOUNDARY")
  private Boundary northBoundary;

  @ManyToOne
  @JoinColumn(name="EAST_BOUNDARY")
  private Boundary eastBoundary;

  @ManyToOne
  @JoinColumn(name="SOUTH_BOUNDARY")
  private Boundary southBoundary;

  @ManyToOne
  @JoinColumn(name="WEST_BOUNDARY")
  private Boundary westBoundary;
}