我在以前的开发中经常遇到这样的场景：文件上传之后需要显示文件名，但是asp.net自带的fileupload是不能付给上传后的文件名值的。

以前都是做一个label显示的，今天想起来了，写个控件封装一下,直接上代码

控件的代码:

using System;using System.Collections.Generic;using System.ComponentModel;using System.Text;using System.Web;using System.Web.UI;using System.Web.UI.WebControls;namespace Fang{    [DefaultProperty("Text")]    [ToolboxData("<{0}:FangFileUpload runat=server>
     ")]    public class FangFileUpload : FileUpload    {        /// 
        /// 指示是否上传成功,上传成功后直接反应文件名称和一个删除按钮        /// 
        [        Browsable(false),        Description("设置或获取是否上传成功的标记")        ]        public bool IsUploaded        {            get { return ViewState["IsUploaded"] == null ? false : (bool)ViewState["IsUploaded"]; }            set { ViewState["IsUploaded"] = value; }        }        /// 
        /// 上传成功的文件名啊        /// 
        public string UploadedFileName        {            get { return ViewState["UploadedFileName"] == null ? null : ViewState["UploadedFileName"].ToString(); }            set { ViewState["UploadedFileName"] = value; }        }        /// 
        /// 微软默认在这里加了file属性，去掉        /// 
        ///         protected override void AddAttributesToRender(HtmlTextWriter writer)        {            //没有上传的时候客户端才需要id和name            if (!this.IsUploaded)            {                string uniqueID = this.UniqueID;                if (uniqueID != null)                {                    writer.AddAttribute(HtmlTextWriterAttribute.Name, uniqueID);                }                string clientID = this.ClientID;                if (clientID != null)                {                    writer.AddAttribute(HtmlTextWriterAttribute.Id, clientID);                }            }        }        /// 
        /// 判断是应该显示div,还是file        /// 
        protected override HtmlTextWriterTag TagKey        {            get            {                if (IsUploaded)                {                    return HtmlTextWriterTag.P;                }                else                {                    return HtmlTextWriterTag.Input;                }            }        }        /// 
        /// 输出div或者file        /// 
        ///         protected override void Render(HtmlTextWriter writer)        {            if (!IsUploaded)            {                writer.AddAttribute(HtmlTextWriterAttribute.Type, "file");                base.Render(writer);            }            else            {                base.RenderBeginTag(writer);                writer.Write(string.IsNullOrEmpty(UploadedFileName) ? "未命名上传文件" : UploadedFileName);                base.RenderEndTag(writer);            }        }    }}

　　

测试代码：

<%@ Page Language="C#" AutoEventWireup="true"  CodeFile="Default.aspx.cs" Inherits="_Default" %><%@ Register Assembly="FangFileUpload" Namespace="Fang" TagPrefix="Fang" %>
             
     
    
              
      
        
          
     

　　

using System;using System.Collections.Generic;using System.Web;using System.Web.UI;using System.Web.UI.WebControls;public partial class _Default : System.Web.UI.Page{    protected void Page_Load(object sender, EventArgs e)    {    }    protected void btn_Click(object sender, EventArgs e)    {        if (FangFileUpload1.HasFile)        {            FangFileUpload1.SaveAs(Server.MapPath("~/upload/") + FangFileUpload1.FileName);            //上传成功            FangFileUpload1.IsUploaded = true;            FangFileUpload1.UploadedFileName = FangFileUpload1.FileName;        }    }}