请教C#做限速下载

Question

我现在想做一个简单的下载工具，就是制定一个下载的url地址。然后自己在程序中输入50k每秒。那么我这个程序的下载速度就被限制到50k每秒了。【不管是1个线程下载还是多个线程下载，总之就是所有的线程下载和就是 50k每秒】。这个如何实现呢？

Answer 1

从网上来的，楼主也可以google一下啊protected void DoDownLoad(long lngSpeed)
{
Page.Response.Clear();
bool success = ResponseFile(Page.Request, Page.Response, "下载时显示的名称.rar", "E:\\WWWROOT\\files\\www.linjunjie.net.rar", lngSpeed);
if (!success)
{
Response.Write("下载文件出错！");
}
else
{
Response.Write("下载文件成功！");
}
Page.Response.End();
}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;
double pack = 1024;
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());
_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(int.Parse(pack.ToString())));
Thread.Sleep(sleep);
}
else
{
i = maxCount;
}
}
}
catch (Exception e4)
{
System.Web.HttpContext.Current.Response.Write(e4.Message);
return false;
}
finally
{
br.Close();
myFile.Close();
}
}
catch (Exception e3)
{
System.Web.HttpContext.Current.Response.Write(e3.Message);
return false;
}
return true;
}protected void Button1_Click(object sender, EventArgs e)
{
DoDownLoad(5 * 1024);
}
protected void Button2_Click(object sender, EventArgs e)
{
DoDownLoad(50 * 1024);
}

Answer 2

/// <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;
}