C#文件下载方法代码

//得到下载文件的ContentType

public string GetFileContentType(string filename)

{

string[] array = filename.Split('.');

string result = string.Empty;

string suffix = "." + array[array.Length - 1];

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;

}

public bool DownloadFiles(string filePath,string fileName,out long filelengh)

{

filelengh = 0;

try

{

//string fileName = "asd.txt";//客户端保存的文件名

//string filePath = Server.MapPath("DownLoad/aaa.txt");//路径

FileInfo fileInfo = new FileInfo(filePath); //filePath为文件在服务器的全路径，包含文件名。

Response.Clear();

Response.ClearContent();

Response.ClearHeaders();

Response.AddHeader("Content-Disposition", "attachment;filename=" + fileName);

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

filelengh = fileInfo.Length;

Response.AddHeader("Content-Transfer-Encoding", "binary");

Response.Charset = "GB2312";

Response.ContentType = GetFileContentType(fileName); //调用下载文件的ContentType

Response.ContentEncoding = System.Text.Encoding.GetEncoding("gb2312");

Response.WriteFile(fileInfo.FullName);

Response.Flush();

Response.End();

return true;

}

catch (Exception)

{

return false;

}

}

调用方法：

if (!IsPostBack)

{

string type = Request.QueryString["filetype"].ToString();

string path =string.Empty;

switch (type)

{

case "chengguo":

path = "~\\Files\\";

break;

case "data":

path = "~\\DataFiles\\";

break;

default:

break;

}

string name = Request.QueryString["filename"].ToString();

string fullpath = Server.MapPath(path+name);

long filelength;

bool su=DownloadFiles(fullpath, name, out filelength); //调用方法

if (!su)

{

ClientScript.RegisterStartupScript(GetType(), "Message", "<SCRIPT LANGUAGE='javascript'>alert('该文件不存在,或下载出错!');</script>");

}

}