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）

// 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
publicstatic 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(newchar[] {'=','-'});
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