如何从视图访问数据或应用程序模型？

Question

I'm relatively new to writing big graphical applications, and as a project I have to write a game in Java that uses swing, while using proper software engineering principles. I've decoupled the graphical interface from the logic of the game, but now I have no idea how I can get access to all the data I need to populate in the view.

For example, I have a class called 'Board' that has a reference to a list of 'Territory' objects, which in turn each have a reference to a polygon object for the relevant area of the map. I want to make a custom JPanel that displays a graphical world map, and get the collection of territories from the board object so I can make the map interactive by using the polygon objects.

I thought about using some form of singleton or factory design patten so I could access all the data as needed, but it's seems that a singleton is not what I want, and I don't even understand the factory patten well enough to determine if it's what I want our not. Am I going to be forced to pass a reference to all my objects to each component of the GUI, or is there a better way?

---

Here's some of my code, though I don't know how much help it will be at this stage.

public class MapPanel extends JPanel {

    private Image image;
    private List<Territory> territories;

    public MapPanel() {
        try {
            BufferedInputStream in = new BufferedInputStream(
                    ClassLoader.getSystemResourceAsStream("MapBig.jpg"));
            image = ImageIO.read(in);
        } catch (IOException ex) {
            // handle exception...
        }

        initialize();
    }

    private void initialize() {
        this.setPreferredSize(new Dimension(900, 600));
    }

    public void setBackground(Image i) {
        this.image = i;
        repaint();
    }

    public void paintComponent(final Graphics g) {
        super.paintComponent(g);
        g.drawImage(image, 0, 0, null);
    }
}

And my Board class:

public class Board {

  private List<Territory> territories;
  //private List<List<Tile>> rows;

  public Board(List<Territory> territories) {
    this.territories = territories;
  }

  public Iterator<Territory> getTerritories() {
    return territories.iterator();
  }
}

And my Territory class which holds the polygons I want to make use of.

public class Territory implements java.io.Serializable {

  //region Private Variables
  /**
   * 
   */
  private static final long serialVersionUID = 5360937073507663827L;

  /**
   * The territory's name. 
   */
  private String name;

  /**
   * The representation of this territory in 2d space. 
   */
  private Polygon region;

  /**
   * List of Player objects currently residing in this geographical area
   * of the world map.
   */
  private List<Player> players;

  /**
   * Country that owns this territory.
   */
  private Country owner;

  /**
   * List of neighboring territories that can be traveled to.
   */
  private List<Territory> neighbors;
  //endregion Private Variables

  public Territory(String name, Polygon region) {
    this.name = name;
    this.region = region;
    players = new ArrayList<Player>();
    owner = null;
  }

  /**
   * Get the name of this territory.
   * @return    name of this territory
   */
  public String getName() { return name; }
  /**
   * Set the name of this territory.
   * @param name    name to give this territory
   */
  public void setName(String name) { this.name=name; }
  /**
   * Get the bounded region for this territory.
   * @return    a Polygon object representing the 2D bounds of this
   * territory
   */
  public Polygon getRegion() { return region; }
  /**
   * Set the bounded region for this territory.
   * @param region  a Polygon object representing the 2D bounds of this
   * territory
   */
  public void setRegion(Polygon region) { this.region=region; }
  /**
   * Get the owning Country.
   * @return    the Country object that owns the geograpical area bounded
   * by this territory.
   */
  public Country getCountry() { return owner; }
  /**
   * Set the owning Country.
   * @param country the Country object that owns the geograpical area 
   * bounded by this territory.
   */
  public void setCountry (Country country) { this.owner=country; }
  public Iterator<Territory> getNeighbors() { return neighbors.iterator(); }
  public void setNeighbors(List<Territory> neighbors) { this.neighbors = neighbors; }

  /**
   * Get a list of all Player objects currently residing in this geographical 
   * area of the world map.
   * @return    an Iterator over a List of Player objects
   */
  public Iterator<Player> getPlayers() { return players.iterator(); }
  /**
   * Adds a player to this Territory
   * @param player  Player object to add to this Territory
   */
  public void addPlayer(Player player) { players.add(player); }
  /**
   * 
   * @param player
   */
  public void removePlayer(Player player) { players.remove(player); }
}

Answer 1

You need to use the observable pattern to communicate between components of the MVC pattern. In addition, you might want to consider using the Facade pattern to make sure the communication is simplified.

Model: all game logic (also holds the list of objects!) Controller: Interprets user input on the GUI View: Reports action on the gui.

Check out this: http://en.wikipedia.org/wiki/Model%E2%80%93view%E2%80%93controller