ASP.NET文件的上传下载

【实例截图】

【核心代码】

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.IO;

namespace WebApplication1
{
    public partial class WebForm1 : System.Web.UI.Page
    {
        protected void Page_Load(object sender, EventArgs e)
        {

        }

        protected void BtnUpload_Click(object sender, EventArgs e)
        {
            if (FileUpload1.HasFile)
            {
                string fileName = FileUpload1.FileName;//获取上传的文件名
                this.TextBox1.Text = fileName;
                //获取上传文件的后缀名
                String filefix = fileName.Substring(fileName.LastIndexOf('.')   1).ToLower();
                if (filefix!="png"&&filefix!="jpg"&&filefix!="jpeg"&&filefix!="gif")
                {
                    FileUpload1.SaveAs(Server.MapPath(".")   "//UploadPic//"   fileName);
                    this.ImgPic.ImageUrl = "";
                    this.lblMessage.Text = "文件上传成功！";
                    
                }
                else
                {
                    FileUpload1.SaveAs(Server.MapPath(".")   "//UploadPic//"   fileName);
                    this.ImgPic.ImageUrl = "~/UploadPic/"   fileName;
                    this.lblMessage.Text = "图片上传成功！";
                }
            }
        }

        protected void btnDownload_Click(object sender, EventArgs e)
        {
            string name = this.TextBox1.Text;
            //MessageBox.Show(name);
            string filename = Server.MapPath(".")   "/UploadPic/"   name;
            FileInfo fileinfo = new FileInfo(filename);
            Response.Clear();
            Response.Charset = "GB2312";
            Response.ContentEncoding = System.Text.Encoding.UTF8;
            Response.AddHeader("Content-Disposition", "attachment;filename="   Server.UrlEncode(fileinfo.Name));
            Response.AddHeader("Content-Length", fileinfo.Length.ToString());
            Response.ContentType = "application/x-bittorrent";
            Response.WriteFile(fileinfo.FullName);
            Response.End();
            //Response.ContentType = "application/x-zip-compressed";
            //Response.AddHeader("Content-Disposition", "attachment;filename="   name);
            //Response.TransmitFile(filename);
        }
    }
}