/// <summary>
/// 分块下载文件
/// </summary>
/// <param name="Address">URL 地址</param>
/// <param name="FileName">保存到本地的路径文件名</param>
/// <param name="ChunksCount">块数,线程数</param>
public void DownloadFile(string Address, string FileName, int ChunksCount)
{
int p = 0; // position
int s = 0; // chunk size
string a = null;
HttpWebRequest hwrq;
HttpWebResponse hwrp = null;
try
{
hwrq = (HttpWebRequest)WebRequest.Create(this.GetUri(Address));
hwrp = (HttpWebResponse)hwrq.GetResponse();
long L = hwrp.ContentLength;
hwrq.Credentials = this.m_credentials;
L = ((L == -1) || (L > 0x7fffffff)) ? ((long)0x7fffffff) : L; //Int32.MaxValue 该常数的值为 2,147,483,647; 即十六进制的 0x7FFFFFFF
int l = (int)L;
this._FileLength = l;
// 在本地预定空间(竟然在多线程下不用先预定空间)
// FileStream sw = new FileStream(FileName, FileMode.OpenOrCreate, FileAccess.ReadWrite, FileShare.ReadWrite);
// sw.Write(new byte[l], 0, l);
// sw.Close();
// sw = null;
bool b = (hwrp.Headers["Accept-Ranges"] != null & hwrp.Headers["Accept-Ranges"] == "bytes");
a = hwrp.Headers["Content-Disposition"]; //attachment
if (a != null)
{
a = a.Substring(a.LastIndexOf("filename=") + 9);
}
else
{
a = FileName;
}
int ss = s;
if (b)
{
s = l / ChunksCount;
if (s < 2 * 64 * 1024) //块大小至少为 128 K 字节
{
s = 2 * 64 * 1024;
}
ss = s;
int i = 0;
while (l > s)
{
l -= s;
if (l < s)
{
s += l;
}
if (i++ > 0)
{
var x = new DownLoadState(Address, hwrp.ResponseUri.AbsolutePath, FileName, a, p, s, new ThreadCallbackHandler(DownloadFileChunk))
{
httpWebClient = this
};
////单线程下载
// x.StartDownloadFileChunk();
//多线程下载（大文件）
Thread t = new Thread(new ThreadStart(x.StartDownloadFileChunk));
//this.OnThreadProcess(t);
t.Start();
}
p += s;
}
s = ss;
byte[] buffer = this.ResponseAsBytes(Address, hwrp, s, FileName);
this.OnThreadProcess(Thread.CurrentThread);
// lock (_SyncLockObject)
// {
// this._Bytes += buffer.Length;
// }
}
}
catch (Exception e)
{
ExceptionActions ea = ExceptionActions.Throw;
if (this.ExceptionOccurrs != null)
{
DownLoadState x = new DownLoadState(Address, hwrp.ResponseUri.AbsolutePath, FileName, a, p, s);
ExceptionEventArgs eea = new ExceptionEventArgs(e, x);
ExceptionOccurrs(this, eea);
ea = eea.ExceptionAction;
}
if (ea == ExceptionActions.Throw)
{
if (!(e is WebException) && !(e is SecurityException))
{
throw new WebException("net_webclient", e);
}
//throw;
}
}
}
internal byte[] ResponseAsBytes(string RequestURL, WebResponse Response, long Length, string FileName)
{
string a = null; //AttachmentName
int P = 0; //整个文件的位置指针
int num2 = 0;
try
{
a = Response.Headers["Content-Disposition"]; //attachment
if (a != null)
{
a = a.Substring(a.LastIndexOf("filename=") + 9);
}
long num1 = Length; //Response.ContentLength;
bool flag1 = false;
if (num1 == -1)
{
flag1 = true;
num1 = 0x10000; //64k
}
byte[] buffer1 = new byte[(int)num1];
int p = 0; //本块的位置指针
string s = Response.Headers["Content-Range"];
if (s != null)
{
s = s.Replace("bytes ", "");
s = s.Substring(0, s.IndexOf("-"));
P = Convert.ToInt32(s);
}
int num3 = 0;
Stream S = Response.GetResponseStream();
do
{
num2 = S.Read(buffer1, num3, ((int)num1) - num3);
num3 += num2;
if (flag1 && (num3 == num1))
{
num1 += 0x10000;
byte[] buffer2 = new byte[(int)num1];
Buffer.BlockCopy(buffer1, 0, buffer2, 0, num3);
buffer1 = buffer2;
}
// lock (_SyncLockObject)
// {
// this._bytes += num2;
// }
if (num2 > 0)
{
if (this.DataReceive != null)
{
byte[] buffer = new byte[num2];
Buffer.BlockCopy(buffer1, p, buffer, 0, buffer.Length);
DownLoadState dls = new DownLoadState(RequestURL, Response.ResponseUri.AbsolutePath, FileName, a, P, num2, buffer);
DownLoadEventArgs dlea = new DownLoadEventArgs(dls);
//触发事件
this.OnDataReceive(dlea);
//System.Threading.Thread.Sleep(100);
}
p += num2; //本块的位置指针
P += num2; //整个文件的位置指针
}
else
{
break;
}
}while (num2 != 0);
S.Close();
S = null;
if (flag1)
{
byte[] buffer3 = new byte[num3];
Buffer.BlockCopy(buffer1, 0, buffer3, 0, num3);
buffer1 = buffer3;
}
return(buffer1);
}
catch (Exception e)
{
var ea = ExceptionActions.Throw;
if (this.ExceptionOccurrs != null)
{
var x = new DownLoadState(RequestURL, Response.ResponseUri.AbsolutePath, FileName, a, P, num2);
var eea = new ExceptionEventArgs(e, x);
ExceptionOccurrs(this, eea);
ea = eea.ExceptionAction;
}
if (ea == ExceptionActions.Throw)
{
if (!(e is WebException) && !(e is SecurityException))
{
throw new WebException("net_webclient", e);
}
//throw;
}
return(null);
}
}
