response下载文件 （转载）

核心代码：

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DataSet ds = dBll.GetList("ID=" + ID);

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string docName = "a.doc";//文件名，

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        byte[] file = (byte[])ds.Tables[0].Rows[0]["FContent"]; //   "FContent"类型为image

        string Type = checktype(docName);

        Response.AddHeader("Content-Disposition", "attachment;filename=" + HttpUtility.UrlEncode(docName, System.Text.Encoding.UTF8).Replace("+", "%20"));

        Response.AddHeader("Content-Length ", file.Length.ToString());

        Response.ContentType = Type;

        Response.BinaryWrite(file);//可以下载二进制文件，如数据库存的image

        //Response.WriteFile(fliePath);可以下载路径文件

          Response.End();

        Response.Clear();

 

/// <summary>

/// 根据文件的扩展名来获取对应的“输出流的HTTP MIME“类型

/// </summary>

/// <param name="filename"></param>

/// <returns></returns>

private string checktype(string filename)

{

    string ContentType;

    switch (filename.Substring(filename.LastIndexOf(".")).Trim().ToLower())

    {

        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;

}

 HttpUtility.UrlEncode(docName, System.Text.Encoding.UTF8).Replace("+", "%20"));这个可以解决中文文件名中包含空格的问题，UrlEncode编码后会把文件名中的空格转换中+（+转换为%2b），但是浏览器是不能理 解加号为空格的，所以在浏览器下载得到的文件，空格就变成了加号；
解决办法：UrlEncode 之后, 将 “+” 替换成 “%20″，因为浏览器将%20转换为空格