//输出硬盘文件，提供下载支持大文件、续传、速度限制、资源占用小
//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
publicstaticboolResponseFile(HttpRequest_Request,HttpResponse_Response,string_fileName,string_fullPath,long_speed)
{
try
{
FileStreammyFile=newFileStream(_fullPath,FileMode.Open,FileAccess.Read,FileShare.ReadWrite);
BinaryReaderbr=newBinaryReader(myFile);
try
{
_Response.AddHeader("Accept-Ranges","bytes");
_Response.Buffer=false;
longfileLength=myFile.Length;
longstartBytes=0;

intpack=10240;//10Kbytes
//intsleep=200;//每秒5次即5*10Kbytes每秒
intsleep=(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);
intmaxCount=(int)Math.Floor((fileLength-startBytes)/pack)+1;

for(inti=0;i<maxCount;i++)
{
if(_Response.IsClientConnected)
{
_Response.BinaryWrite(br.ReadBytes(pack));
Thread.Sleep(sleep);
}
else
{
i=maxCount;
}
}
}
catch
{
returnfalse;
}
finally
{
br.Close();
myFile.Close();
}
}
catch
{
returnfalse;
}
returntrue;
}

Page.Response.Clear();

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

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

Page.Response.End();