收藏：ASP.NET提供文件下载函数（支持大文件、续传、速度限制、资源占用小） (转自： Arhrun)

// 输出硬盘文件，提供下载
// 输入参数 _Request: Page.Request对象， _Response: Page.Response对象， _fileName: 下载文件名， _fullPath: 带文件名下载路径， _speed 每秒允许下载的字节数
// 返回是否成功
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 ;
long fileLength = myFile.Length;
long startBytes = 0 ;

int 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 {0}-{1}/{2} " , 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(pack));
Thread.Sleep(sleep);
}
else
{
i = maxCount;
}
}
}
catch
{
return false ;
}
finally
{
br.Close();
myFile.Close();
}
}
catch
{
return false ;
}
return true ;
}

调用例

Page.Response.Clear();

bool success = ResponseFile(Page.Request, Page.Response, "filename", @"C:\download.date", 1024000);

if(!success)
Response.Write("下载文件出错！");
Page.Response.End();

通过这种方式实现的下载，可控性好，可以控制读取文件块的大小，可以有效的实现防盗、可以监控资源的下载等等。如果你能把他封装的很好的话，这将是一个非常强大的类