我想从这个代码的ftp服务器下载文件：
using (System.IO.FileStream fileStream = System.IO.File.OpenWrite(filePath))
{
byte[] buffer = new byte[4096];
int bytesRead = responseStream.Read(buffer, 0, 4096);
while (bytesRead > 0)
{
fileStream.Write(buffer, 0, bytesRead);
bytesRead = responseStream.Read(buffer, 0, 4096);
}
}
responseStream的创建：
System.IO.Stream responseStream = GetFileAsStream(url, username, password, false);
public static System.IO.Stream GetFileAsStream(string ftpUrl, string username, string password, bool usePassive)
{
System.Net.FtpWebRequest request = (System.Net.FtpWebRequest)System.Net.WebRequest.Create(ftpUrl);
request.KeepAlive = false;
request.ReadWriteTimeout = 120000;
request.Timeout = -1;
request.UsePassive = usePassive;
request.Credentials = new System.Net.NetworkCredential(username, password);
request.Method = System.Net.WebRequestMethods.Ftp.DownloadFile;
System.IO.Stream fileResponseStream;
System.Net.FtpWebResponse fileResponse = (System.Net.FtpWebResponse)request.GetResponse();
fileResponseStream = fileResponse.GetResponseStream();
return fileResponseStream;
}
它正常工作与更小的文件，但是当文件较大（如150MB），该过程将挂起。 出于某种原因，程序不明白，它已经完成了下载，它仍然尝试读取多个字节。
我喜欢的答案不包括使用外部库。 谢谢
我已经成功下载使用你的代码超过150MB的几个文件。 正如其他人所建议的，它很可能与你的FTP服务器有问题。
我已经通过引入请求timeout-，如果达到，使得节目抛出引发WebException解决我的问题。 在这种情况下，程序会从上次的地方下载。 这里是我的代码：
这是如果文件被下载它返回true的方法中，假否则
Digitalez.DirectoryUtil.EnsureDirectoryExists(relativePath);
string filePath = System.IO.Path.Combine(relativePath, fileInfo.Name);
long length = Digitalez.FtpUtil.GetFileLength(fileInfo.FullPath, userName, password, usePassive);
long offset = 0;
int retryCount = 10;
int? readTimeout = 5 * 60 * 1000; //five minutes
// if the file exists, do not download it
if (System.IO.File.Exists(filePath))
{
return false;
}
while (retryCount > 0)
{
using (System.IO.Stream responseStream = Captator.Eifos.Net.FtpUtil.GetFileAsStream(fileInfo.FullPath, userName, password, usePassive, offset, requestTimeout: readTimeout != null ? readTimeout.Value : System.Threading.Timeout.Infinite))
{
using (System.IO.FileStream fileStream = new System.IO.FileStream(filePath, System.IO.FileMode.Append))
{
byte[] buffer = new byte[4096];
try
{
int bytesRead = responseStream.Read(buffer, 0, buffer.Length);
while (bytesRead > 0)
{
fileStream.Write(buffer, 0, bytesRead);
bytesRead = responseStream.Read(buffer, 0, buffer.Length);
}
return true;
}
catch (System.Net.WebException)
{
// Do nothing - consume this exception to force a new read of the rest of the file
}
}
if (System.IO.File.Exists(filePath))
{
offset = new System.IO.FileInfo(filePath).Length;
}
else
{
offset = 0;
}
retryCount--;
if (offset == length)
{
return true;
}
}
}
Digitalez.FtpUtil：
public static System.IO.Stream GetFileAsStream(string ftpUrl, string username, string password, bool usePassive, long offset, int requestTimeout)
{
System.Net.FtpWebRequest request = (System.Net.FtpWebRequest)System.Net.WebRequest.Create(ftpUrl);
request.KeepAlive = false;
request.ReadWriteTimeout = requestTimeout;
request.Timeout = requestTimeout;
request.ContentOffset = offset;
request.UsePassive = usePassive;
request.UseBinary = true;
request.Credentials = new System.Net.NetworkCredential(username, password);
request.Method = System.Net.WebRequestMethods.Ftp.DownloadFile;
System.IO.Stream fileResponseStream;
System.Net.FtpWebResponse fileResponse = (System.Net.FtpWebResponse)request.GetResponse();
fileResponseStream = fileResponse.GetResponseStream();
return fileResponseStream;
}
public static long GetFileLength(string ftpUrl, string username, string password, bool usePassive)
{
System.Net.FtpWebRequest request = (System.Net.FtpWebRequest)System.Net.WebRequest.Create(ftpUrl);
request.KeepAlive = false;
request.UsePassive = usePassive;
request.Credentials = new System.Net.NetworkCredential(username, password);
request.Method = System.Net.WebRequestMethods.Ftp.GetFileSize;
System.Net.FtpWebResponse lengthResponse = (System.Net.FtpWebResponse)request.GetResponse();
long length = lengthResponse.ContentLength;
lengthResponse.Close();
return length;
}
我还没有尝试过其他的服务器，但是这肯定不会把戏。
