[上传下载] C#修改DownLoadHelper上传下载帮助类 （转载）

/// <summary>
///  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
/// </summary>
/// <param name="_Request">Page.Request对象</param>
/// <param name="_Response">Page.Response对象</param>
/// <param name="_fileName">下载文件名</param>
/// <param name="_fullPath">带文件名下载路径</param>
/// <param name="_speed">每秒允许下载的字节数</param>
/// <returns>返回是否成功</returns>

/// <summary>
/// 编 码 人：苏飞
/// 联系方式：361983679
/// 更新网站：http://www.sufeinet.com/thread-655-1-1.html
/// </summary>
using System;
using System.IO;
using System.Web;
using System.Threading;

namespace DotNet.Utilities
{
/// <summary>
/// 文件下载帮助类
/// </summary>
public class DownLoadHelper
{
#region ResponseFile 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
/// <summary>
///  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
/// </summary>
/// <param name="_Request">Page.Request对象</param>
/// <param name="_Response">Page.Response对象</param>
/// <param name="_fileName">下载文件名</param>
/// <param name="_fullPath">带文件名下载路径</param>
/// <param name="_speed">每秒允许下载的字节数</param>
/// <returns>返回是否成功</returns>
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((double)(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((double)((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;
}
#endregion
}
}