Question

我正在创建自己的UI绑定系统，该系统将控件绑定到关联对象。什么比使用一系列if语句更好？如果我添加新控件来提供新的跟踪项，我不希望每次都更新这一系列的if语句。

TimelineTrackControl control;
Type objectType = track.GetType();

if (objectType == typeof(ShotTrack))
{
    control = new ShotTrackControl();
}
else if (objectType == typeof(AudioTrack))
{
    control = new AudioTrackControl();
}
else if (objectType == typeof(GlobalItemTrack))
{
    control = new GlobalItemTrackControl();
}
else
{
    control = new TimelineTrackControl();
}

control.TargetTrack = track;
timelineTrackMap.Add(track, control);

Answer 1

您可以使用反射，在这种情况下http://msdn.microsoft.com/en-us/library/vstudio/d133hta4就像这样：

Activator.CreateInstance(null, track.GetType().toString() + "Control");

Answer 2

你可以：

创建一个包含曲目类型和相应控件类型的Dictionary<Type, Type>：

private static readonly Dictionary<Type, Type> ControlTypes = new Dictionary<Type, Type>
{
    { typeof(ShotTrack), typeof(ShotTrackControl) },
    ...
};

获得相应的控制：

control = Activator.CreateInstance(ControlTypes[track.GetType()]);

创建一个包含曲目类型和相应控件创建者的Dictionary<Type, Func<Control>>：

private static readonly Dictionary<Type, Func<Control>> ControlTypes = new Dictionary<Type, Func<Control>>
{
    { typeof(ShotTrack), () => new ShotTrackControl() },
    ...
};

要创建新的相应控件：

control = ControlTypes[track.GetType()]();

定义存储相应控件类型的自定义属性：

[AttributeUsage(AttributeTargets.Class, AllowMultiple = false)]
public class TrackControlAttribute : Attribute
{
    public readonly Type ControlType;

    public TrackControlAttribute(Type controlType)
    {
        ControlType = controlType;
    }
}

[TrackControl(typeof(ShotTrackControl))]
public class ShotTrack
{
    ...
}

要创建新的相应控件：

object[] attrs = track.GetType().GetCustomAttributes(typeof(TrackControlAttribute), true);
if (attrs.Length != 0);
    control = Activator.CreateInstance(((TrackControlAttribute)attrs[0]).ControlType);

修改
在第3个选项中修复了错误。

自定义UI将对象绑定到控件

2 个答案: