C#文件上传与下载

谁借莪１个温暖的怀抱￠ 2021-09-12 06:54 506阅读 0赞

**1、C\#文件上传**

创建MyUpload.htm页面，用于测试

创建UploadFile.aspx文件，在UploadFile.aspx.cs键入如下代码：

Random rnd = new Random();                            //产生随机数
    private string _directory = @"/File/UploadFile";      //目录
    protected void Page_Load(object sender, EventArgs e)
    {
        try
        {
            if (Request.Files.Count > 0)
            {
                //判断文件大小
                int length = Request.Files[0].ContentLength;
                if (length > 1048576)
                {
                    Response.Write("文件大于1M，不能上传");
                    return;
                }
    
                string type = Request.Files[0].ContentType;
                string fileExt = Path.GetExtension(Request.Files[0].FileName).ToLower();
                //只能上传图片，过滤不可上传的文件类型
                string fileFilt = ".gif|.jpg|.php|.jsp|.jpeg|.png|......";
                if (fileFilt.IndexOf(fileExt) <= -1)
                {
                    Response.Write("对不起！请上传图片！！");
                    return;
                }
                else
                {
                    string fileName = Server.MapPath(_directory) + "\\" + DateTime.Now.ToString("yyyyMMddHHmmssfff") + rnd.Next(10, 99).ToString() + fileExt;
                    Request.Files[0].SaveAs(fileName);
                    Response.Write("上传成功！");
                }
            }
        }
        catch
        {
            throw new Exception();
        }
    }

**2 、C\#文件下载**

创建DownloadFile.aspx，在DownloadFile.aspx.cs键入如下方法：

/// <summary>
    /// C#文件下载
    /// </summary>
    /// <param name="filename"></param>
    public void MyDownload(string filename)
    {
    
        string path = Server.MapPath("/File/"+filename);
        if(!File.Exists(path))
        {
            Response.Write("对不起！文件不存在！！");
            return;
        }
        System.IO.FileInfo file = new System.IO.FileInfo(path);
        string fileFilt=".asp|.aspx|.php|.jsp|.ascx|.config|.asa|......"; //不可下载的文件，务必要过滤干净
        string fileName = file.Name;
        string fileExt = fileName.Substring(filename.LastIndexOf(".")).Trim().ToLower();
        if(fileFilt.IndexOf(fileExt)!=-1)
        {
            Response.Write("对不起！该类文件禁止下载！！");
        }
        else
        {
            Response.Clear();
            Response.AddHeader("Content-Disposition", "attachment; filename=" + HttpUtility.UrlEncode(fileName));
            Response.AddHeader("Content-Length", file.Length.ToString());
            Response.ContentType = GetContentType(HttpUtility.UrlEncode(fileExt));
            Response.WriteFile(file.FullName);
            Response.End();
        }
    }
    
    /// <summary>
    /// 获取下载类型
    /// </summary>
    /// <param name="fileExt"></param>
    /// <returns></returns>
    public string GetContentType(string fileExt)
    {
        string ContentType;
        switch (fileExt)
        {
            case ".asf":
                ContentType = "video/x-ms-asf"; break;
            case ".avi":
                ContentType = "video/avi"; break;
            case ".doc":
                ContentType = "application/msword"; break;
            case ".zip":
                ContentType = "application/zip"; break;
            case ".xls":
                ContentType = "application/vnd.ms-excel"; break;
            case ".gif":
                ContentType = "image/gif"; break;
            case ".jpg":
                ContentType = "image/jpeg"; break;
            case ".jpeg":
                ContentType = "image/jpeg"; break;
            case ".wav":
                ContentType = "audio/wav"; break;
            case ".mp3":
                ContentType = "audio/mpeg3"; break;
            case ".mpg":
                ContentType = "video/mpeg"; break;
            case ".mepg":
                ContentType = "video/mpeg"; break;
            case ".rtf":
                ContentType = "application/rtf"; break;
            case ".html":
                ContentType = "text/html"; break;
            case ".htm":
                ContentType = "text/html"; break;
            case ".txt":
                ContentType = "text/plain"; break;
            default:
                ContentType = "application/octet-stream";
                break;
        }
        return ContentType;
    }

\*如何获取现有文件的ContentType属性

/// <summary>
    /// 获取现有文件的ContentType属性
    /// </summary>
    /// <param name="filename"></param>
    /// <returns></returns>
    public string GetFileContentType(string filename)
    {
        string[] array = filename.Split('.');
        string result = string.Empty;
        string suffix = "." + array[array.Length - 1];
        Microsoft.Win32.RegistryKey rg = Microsoft.Win32.Registry.ClassesRoot.OpenSubKey(suffix);
        object obj = rg.GetValue("Content Type");
        result = obj != null ? obj.ToString() : string.Empty;
        rg.Close();
        return result;
    }