cs代码如下：

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

public partial class 文件读取 : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        if (!IsPostBack)
        {
            string[] arrs = Directory.GetFiles(MapPath("files"), "*.txt");//Directory
            ///获取路径
            //foreach (string _s in arrs)
            //{


            //    Response.Write(_s + "<br/>");//读取完整物理路径

            //}
            //Response.Write("-----------------------------------------------------------------------" + "<br/>");
            //foreach (string _s in arrs)
            //{

            //    string _fname = Path.GetFileName(_s);//path类下的GetFileName
            //    Response.Write(_fname + "<br/>");//读取文件名


            //}
            //Response.Write("-----------------------------------------------------------------------" + "<br/>");
            //foreach (string _s in arrs)
            //{


            //    string _fname1 = Path.GetFileNameWithoutExtension(_s);
            //    Response.Write(_fname1 + "<br/>");//不带扩展名的文件名

            //}
            ListItem li;
            foreach (string _s in arrs)
            {
                li = new ListItem();
                string fname = Path.GetFileName(_s);
                li.Text = fname;
                DropDownList1.Items.Add(li);

            }
        }
        


    }
    protected void btn_read_Click(object sender, EventArgs e)
    {
        string _fname = DropDownList1.SelectedValue;
        //Response.Write(_fname);
        string _path =Path.Combine( MapPath("files"),_fname);
      
        if(File.Exists(_path)){//判断是否存在，重要步骤
            TextBox1.Text = File.ReadAllText(_path);//读取显示
        

    }
    }
    protected void btn_save_Click(object sender, EventArgs e)
    {
        string _fname = DropDownList1.SelectedValue;//获取下拉框选择项
        //Response.Write(_fname);
        string _path = Path.Combine(MapPath("files"), _fname);//拼路径
        string _content = TextBox1.Text;//获取文本框内容
        File.WriteAllText(_path,_content);//写入源文件


    }
}

aspx代码如下：

<%@ Page Language="C#" AutoEventWireup="true" CodeFile="文件读取.aspx.cs" Inherits="文件读取" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
    <title></title>
</head>
<body>
    <form id="form1" runat="server">
    <div>
    
        <asp:DropDownList ID="DropDownList1" runat="server">
        </asp:DropDownList>
        <asp:Button ID="btn_read" runat="server" Text="读取" οnclick="btn_read_Click" />
        <asp:Button ID="btn_save" runat="server" Text="保存" οnclick="btn_save_Click" />
        <br />
        <asp:TextBox ID="TextBox1" runat="server" Height="216px" Width="218px" TextMode="MultiLine"></asp:TextBox>
    
    </div>
    </form>
</body>
</html>

效果如图：

asp.net文件读取和修改保存练习_文件读取