1.最简单的单文件上传(没花头)

效果图：

说明：这是最基本的文件上传，在asp.net1.x中没有这个FileUpload控件，只有html的上传控件，那时候要把html控件转化为服务器控件，很不好用。其实所有文件上传的美丽效果都是从这个FileUpload控件衍生，第一个例子虽然简单却是根本。

后台代码：
using System;
using System.Data;
using System.Configuration;
using System.Collections;
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;

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

    }
    protected void bt_upload_Click(object sender, EventArgs e)
    {
        try
        {
            if (FileUpload1.PostedFile.FileName == "")
            {
                this.lb_info.Text = "请选择文件！";
            }
            else
            {
                string filepath = FileUpload1.PostedFile.FileName;
                string filename = filepath.Substring(filepath.LastIndexOf("\\") + 1);
                string serverpath = Server.MapPath("images/") + filename;
                FileUpload1.PostedFile.SaveAs(serverpath);
                this.lb_info.Text = "上传成功！";
            }
        }
        catch (Exception ex)
        {
            this.lb_info.Text = "上传发生错误！原因是：" + ex.ToString();
        }
    }
}

前台代码：
 <table style="width: 343px">
            <tr>
                <td style="width: 100px">
                    单文件上传</td>
                <td style="width: 100px">
                </td>