扩展方法应用

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Windows.Forms;

namespace TaskManager
{
    public static class ValidateHelper
    {
        static ValidateHelper()
        {
            IsErr = false;
        }

        public static bool IsErr
        {
            get;
            set;
        }
        static ErrorProvider ep = new ErrorProvider();
        public static bool Validate(this TextBox ctrl, System.Func<TextBox, bool> func, string errmsg)
        {
            if (!func(ctrl))
            {
                ep.SetError(ctrl, errmsg);
                ctrl.Focus();

                return !(IsErr=true);
            }
            return true;
        }
        public static bool Validate(this ListBox ctrl, System.Func<ListBox, bool> func, string errmsg)
        {
            if (!func(ctrl))
            {
                ep.SetError(ctrl, errmsg);
                ctrl.Focus();

                return !(IsErr = true);
            }
            return true;
        }
        public static void Clear()
        {
            ep.Clear();
            IsErr = false;
        }
    }
}

还是照样上两张图

用法

           ValidateHelper.Clear();
            this.txtName.Validate(t => string.IsNullOrEmpty(t.Text), "不能为空");
            this.lstboxFileList.Validate(t => t.Items.Count < 2, "请加载任务资源包");
            if (ValidateHelper.IsErr)
                return;
           //do sth ha

相关文章链接：

C#学习使用ErrorProvider

http://www.cnblogs.com/sondy/archive/2006/04/16/376254.html

ErrorProvider的用法

http://www.cnblogs.com/sondy/archive/2006/04/16/376254.html

验证能有多优雅

http://www.cnblogs.com/GrayZhang/archive/2008/09/01/1281526.html