asp.net实现文件下载

这是一个网站下载的一段代码：
public partial class download : System.Web.UI.Page
{
BaseClass BaseClass1 = new BaseClass();
protected void Page_Load(object sender, EventArgs e)
{
Page.EnableViewState = false;
/* 微软为Response对象提供了一个新的方法TransmitFile来解决使用Response.BinaryWrite 下载超过400mb的文件时导致Aspnet_wp.exe进程回收而无法成功下载的问题。 代码如下： */
if (!IsPostBack)
{
//从数据库取得文件名
string sqlStr = "select * from sourceDownLoad where sId=" + Request.QueryString["id"];
DataTable dt = BaseClass1.ReadTable(sqlStr);
DataTableReader reader = dt.CreateDataReader();

string sourceName = (string)dt.Rows[0].ItemArray[1];
sourceName.Trim();//消除空格
int index= sourceName.LastIndexOf(".");
string extend = sourceName.Substring(index+1);//扩展名
string fullPath = "~/sourceDLoad/" + sourceName;
fullPath = Server.MapPath(fullPath);
//读出该资源的下载次数
int downloadtimes = 0;
if (reader.Read())//
{
downloadtimes=reader.GetInt32(4);
}
Page.Response.Clear();
bool success = ResponseFile(Page.Request, Page.Response, sourceName ,fullPath , 1024000);
if (!success) Response.Write("下载文件出错！");
else
{
//记录下载次数
downloadtimes++;
sqlStr = "update sourceDownLoad set downloadCounts=" + downloadtimes + " where sId=" + Request.QueryString["id"];
BaseClass1.execsql(sqlStr);
}
Page.Response.End();
}
}
public static bool ResponseFile(HttpRequest _Request, HttpResponse _Response, string _fileName, string _fullPath, long _speed)
{
try
{
FileStream myFile = new FileStream(_fullPath, FileMode.Open, FileAccess.Read, FileShare.ReadWrite);
BinaryReader br = new BinaryReader(myFile);
try
{
_Response.AddHeader("Accept-Ranges", "bytes");
_Response.Buffer = false;//不缓冲
long fileLength = myFile.Length;
long startBytes = 0;
double pack = 10240;
//10K bytes
int sleep = 200;
//每秒5次 即5*10K bytes每秒 int sleep = (int)Math.Floor(1000 * pack / _speed) + 1;
if (_Request.Headers["Range"] != null)
{
_Response.StatusCode = 206;
string[] range = _Request.Headers["Range"].Split(new char[] );
startBytes = Convert.ToInt64(range[1]);
}
_Response.AddHeader("Content-Length", (fileLength - startBytes).ToString());
if (startBytes != 0)
{
//Response.AddHeader("Content-Range", string.Format(" bytes -/", startBytes, fileLength-1, fileLength));
}
_Response.AddHeader("Connection", "Keep-Alive");
_Response.ContentType = "application/octet-stream";
_Response.AddHeader("Content-Disposition", "attachment; filename=" + HttpUtility.UrlEncode(_fileName, System.Text.Encoding.UTF8));
br.BaseStream.Seek(startBytes, SeekOrigin.Begin);
int maxCount = (int)Math.Floor((fileLength - startBytes) / pack) + 1;
for (int i = 0; i < maxCount; i++)
{
if (_Response.IsClientConnected)
{
_Response.BinaryWrite(br.ReadBytes(int.Parse(pack.ToString())));
Thread.Sleep(sleep);
}
else
{
i = maxCount;
}
}
}
catch
{
return false;
}
finally
{
br.Close();
myFile.Close();
}
}
catch
{
return false;
}
return true;
}
//这样就实现了文件下载时,不管是什么格式的文件,都能够弹出打开/保存窗口.

}
9月

先把这些文件放到你的网站管理下的文件夹中。
比如你的网站根目录是d:\site，可在其下建一目录，如dl，即d:\site\dl，
把你的文件放在这个目录下。
将数据库中值输出时，放到超链接中，如下：
dim s as string
s="" & "123.txt" & ""
response.write s

把文件弄到asp.net下面 做个超链接到这个文件 记住是相对地址 就可以了