小记,提供文件下载,并控制下载速度
/// <summary>
/// 输出硬盘文件，提供下载
/// </summary>
/// <param name="context">HttpContext对象</param>
/// <param name="_fullPath">要下载的文件的完整路径</param>
/// <param name="_speed">每秒允许下载的字节数</param>
/// <returns>是否成功</returns>
public static bool ResponseFile(HttpContext context,string _fullPath, long _speed)
{
HttpRequest _Request = context.Request;
HttpResponse _Response = context.Response;
string strFileName = new FileInfo(_fullPath).Name;
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 进行拆包,每包大小
int sleep = (int)Math.Floor(1000 * pack / _speed) + 1; //pack/_speed 每个包发送速度/秒 总的意思:发包频率
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(strFileName,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));
_Response.Flush();
System.Threading.Thread.Sleep(sleep); //线程休息sleep毫秒后继续
}
else
{
i=maxCount;
}
}
}
catch
{
return false;
}
finally
{
br.Close();
myFile.Close();
}
}
catch
{
return false;
}
return true;
}
