如何删除重复代码？AOP和泛型都可以

Question

我有数字- TriangleItem和CircleItem：

public abstract class BaseItem
{
  protected int _id;
  protected string _description;
}

public sealed class TriangleItem : BaseItem
{
  public int TriangleId { get { return _id; } set { _id = value; } }
  public string TriangleDescription { get { return _description; } set { _description = value; } }
}

public sealed class CircleItem : BaseItem
{
  public int CircleId { get { return _id; } set { _id = value; } }
  public string CircleDescription { get { return _description; } set { _description = value; } }
}

我有数字收藏，TriangleBox和CircleBox：

public abstract class BaseBox
{
  public string ItemsXml { get; set; }
  public string Descriptions { get; set; }
  public static abstract BaseBox Boxing( BaseItem[] items );
  public abstract void Unboxing();
}

public sealed class TriangleBox : BaseBox
{
  public static override BaseBox Boxing( BaseItem[] items )
  {
    string[] ids = items.ToList().Cast<TriangleItem>().Select( i => i.TriangleId.ToString() ).ToArray();
    string[] descriptions = items.ToList().Cast<TriangleItem>().Select( i => i.TriangleDescription ).ToArray();

    return new TriangleBox()
    {
      ItemsXml = Util.ToXml( ids ),
      Descriptions = descriptions.Aggregate( ( d, next ) => next + ", " + d )
    };
  }

  public TriangleItem[] Unboxing()
  {
    return Util.FromXml( ItemsXml ).Select( i => new TriangleItem { TriangleId = int.Parse( i ), TriangleDescription = i } ).ToArray();
  }
}

public sealed class CircleBox : BaseBox
{
  public static override BaseBox Boxing( BaseItem[] items )
  {
    string[] ids = items.ToList().Cast<CircleItem>().Select( i => i.CircleId.ToString() ).ToArray();
    string[] descriptions = items.ToList().Cast<CircleItem>().Select( i => i.CircleDescription ).ToArray();

    return new CircleBox()
    {
      ItemsXml = Util.ToXml( ids ),
      Descriptions = descriptions.Aggregate( ( d, next ) => next + ", " + d )
    };
  }

  public CircleItem[] Unboxing()
  {
    return Util.FromXml( ItemsXml ).Select( i => new CircleItem { CircleId = int.Parse( i ), CircleDescription = i } ).ToArray();
  }
}

正如您所看到的，我有几乎相同的方法实现--装箱和取消装箱。我使用这些方法如下：

  public BaseBox Do( BaseItem[] items )
  {
    BaseBox result = null;

    if( items is CircleItem[] )
      result = CircleBox.Boxing( items );
    else if( items is TriangleItem[] )
      result = TriangleBox.Boxing( items );

    return result;
  }

  public TriangleItem[] GetTriangles()
  {
    TriangleBox tb = DB.GetTriangleBox(); // From database
    return tb.Unboxing();
  }

  public CircleItem[] GetCircles()
  {
    CircleBox cb = DB.GetCircleBox(); // From database
    return cb.Unboxing();
  }

我可以长乐一些东西，只有一个拳击和取消装箱的实现？您会在这段代码中更改什么？您不喜欢什么(除了捕获空方法的参数)？如果需要的话，AOP和Generics都可以。

在做的方法中我必须知道项目的类型。如果TriangleBox为0，则必须返回空的items.Length或CircleBox。我要怎么用这个案子写我的方法？

Answer 1

我想你真的需要区分圆圈和三角。任何方式都可以使用基类的自动属性。

public abstract class BaseItem
{
    public int Id { get; set; }
    public string Description { get; set; }
}

public sealed class TriangleItem : BaseItem
{
    // Another TriangleItem class members
}

public sealed class CircleItem : BaseItem
{
    // Another CircleItem class members
}

封装mehtod返回的对象类型不同，这是BaseBox的子类型。这意味着您可以合并它们并将特定的框创建委托给子类。

public abstract class BaseBox
{
    public string ItemsXml { get; set; }
    public string Descriptions { get; set; }

    public BaseBox Boxing(BaseItem[] items)
    {
        var ids = items.ToList().Select(i => i.Id.ToString()).ToArray();
        var descriptions = items.ToList().Select(i => i.Description.ToString()).ToArray();
        var box = CreateBox(Util.ToXml(ids), descriptions.Aggregate((d, next) => next + ", " + d));
        return box;
    }

    public BaseItem[] Unboxing()
    {
        return Util.FromXml(ItemsXml).Select(i => CreateItem(int.Parse(i), i)).ToArray();
    }

    protected abstract BaseBox CreateBox(string itemsXml, string descriptions);

    protected abstract BaseItem CreateItem(int id, string description);
}

对于取消装箱和BaseItem，也可以这样做。

public sealed class TriangleBox : BaseBox
{
    protected override BaseBox CreateBox(string itemsXml, string descriptions)
    {
        return new TriangleBox { ItemsXml = itemsXml, Descriptions = descriptions };
    }

    protected override BaseItem CreateItem(int id, string description)
    {
        return new TriangleItem { Id = id, Description = description };
    }
}

public sealed class CircleBox : BaseBox
{
    protected override BaseBox CreateBox(string itemsXml, string descriptions)
    {
        return new CircleBox { ItemsXml = itemsXml, Descriptions = descriptions };
    }

    protected override BaseItem CreateItem(int id, string description)
    {
        return new CircleItem { Id = id, Description = description };
    }
}

更新:装箱方法应该无效。很有可能改名为“DoBoxing”。

public abstract class BaseBox
{
    ...

    public void Boxing(BaseItem[] items)
    {
        var ids = items.ToList().Select(i => i.Id.ToString()).ToArray();
        var descriptions = items.ToList().Select(i => i.Description.ToString()).ToArray();
        this.ItemsXml = Util.ToXml(ids);
        this.Descriptions = descriptions.Aggregate((d, next) => next + ", " + d);
    }

    ...
}

并称为：

    public BaseBox Do(BaseItem[] items)
    {
        ...

        if (result != null)
        {
            result.Boxing(items);
        }

        return result;
    }