用于处理DBNull问题的DateTimePicker

08/5/3改进版,请大家给些建议.谢谢!

using System;
using System.Collections.Generic;
using System.Text;

using System.Windows.Forms;
using System.ComponentModel;
using System.Text.RegularExpressions;

namespace WinUI
{
    /**//// <summary>
    /// 用于处理DBNull问题的DateTimePicker
    /// </summary>
    public class MDateTimePicker :DateTimePicker
    {
        public object Value
        {
            get
            {
                return base.Value;
            }
            set
            {
                try
                {
                    DateTime dt=Convert.ToDateTime(value);
                    base.Value = dt;
                }
                catch (Exception ex)
                {
                    base.Value = MaxDate;
;
                }
            }
        }
        protected override void OnTextChanged(EventArgs e)
        {
            base.OnTextChanged(e);
            if (Convert.ToDateTime(Value) == MaxDate)
            {
                Format = DateTimePickerFormat.Custom;
                CustomFormat = " ";
            }
            else
            {
                Format = DateTimePickerFormat.Long;
            }
        }
        protected override void OnClick(EventArgs e)
        {
            base.OnClick(e);
            onEdit();
        }
        protected override void OnKeyDown(KeyEventArgs e)
        {
            base.OnKeyDown(e);
            if (e.KeyCode == Keys.Delete)
            {
                this.Value = MaxDate;
            }
            else
            {
                onEdit();
            }
        }
        private void onEdit()
        {
            Format = DateTimePickerFormat.Long;
            Value = DateTime.Now;
        }
        
    }
}