目标:可以自由控制fileupload文本框与命令按钮之间的距离
原理：修改生成的html中的input type=file控件的属性，隐藏其中文本框，加上一个文本框，实现变相的上传控件。
其生成的html原代码为:
<input id='uploadText' value=''/>&nbsp;&nbsp;<input onpropertychange="uploadText.value=this.value;" type="file" name="MyUploadFile1" id="MyUploadFile1" style="width:0px;border-width:0" />
其中红色就为其中的关键，相信大家都看的懂吧，我就不再解释了
呵呵（只改了一下显示其实质还是原来的fileupload）.

using System;
using System.Data;
using System.Configuration;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using System.ComponentModel;

namespace LK.WebControl
{
    /// <summary>
    /// MyUploadFile 的摘要说明
    /// </summary>
    public class MyUploadFile : FileUpload
    {

        public MyUploadFile()
        {
        }

        protected override void AddAttributesToRender(HtmlTextWriter writer)
        {
            writer.AddAttribute(HtmlTextWriterAttribute.Style, "width:0px;border-width:0");
            writer.AddAttribute("onpropertychange", "uploadText.value=this.value;");
            base.AddAttributesToRender(writer);
        }

        #region 属性
        /// <summary>
        /// 文本框与命令按钮的间距
        /// </summary>
        [BrowsableAttribute(true)]
        [DescriptionAttribute("文本框与命令按钮的间距")]
        [CategoryAttribute("外观")]
        public int CellSpace
        {
            get { return _cellSpace; }
            set { _cellSpace = value; }
        }
        private int _cellSpace = 0;

        [BrowsableAttribute(true)]
        [DescriptionAttribute("文本框的样式")]
        [CategoryAttribute("外观")]
        public string TextCss
        {
            get { return _textCss; }
            set { _textCss = value; }
        }
        private string _textCss;

        [BrowsableAttribute(true)]
        [DescriptionAttribute("文本框的宽度")]
        [CategoryAttribute("外观")]
        public string TextWidth
        {
            get { return _textWidth; }
            set { _textWidth = value; }
        }
        private string _textWidth;

        [BrowsableAttribute(true)]
        [DescriptionAttribute("文本框的高度")]
        [CategoryAttribute("外观")]
        public string TextHeight
        {
            get { return _textHeight; }
            set { _textHeight = value; }
        }
        private string _textHeight;
        #endregion

        public override void RenderControl(HtmlTextWriter writer)
        {
            if (Visible)
            {
                string strStyle = "style='{0}'";
                string styleValue = "";
                writer.Write("<input id='uploadText' value='' ");
                if (!string.IsNullOrEmpty(_textWidth))
                    styleValue+= "width:"+_textWidth+"px;";
                if (!string.IsNullOrEmpty(_textHeight))
                    styleValue +="height:"+_textHeight+ "px;";
                if (!string.IsNullOrEmpty(_textCss))
                    writer.Write(" class='" + _textCss + "' ");
                if (!string.IsNullOrEmpty(styleValue))
                    styleValue = string.Format(strStyle,styleValue);
                writer.Write(styleValue );
                writer.Write(" />");
                for (int i = 0; i < _cellSpace; i++)
                {
                    writer.Write("&nbsp;");
                }
            }
            base.RenderControl(writer);
        }
    }
}