如何检查UNC路径是否可用？ 我有一个问题，如果共享不可用，检查大约需要半分钟：
var fi = new DirectoryInfo(@"\\hostname\samba-sharename\directory");
if (fi.Exists)
//...
是否有更快的方法来检查文件夹是否可用？ 我正在使用Windows XP和C＃。
答案 0 :(得分：21)
如何快速而肮脏地检查 - 运行windows net use命令并解析具有感兴趣的网络路径（例如\\vault2）和{的行的输出{1}}。这是输出的一个例子：
OK它不是一个非常强大的解决方案，但速度非常快，有时候更重要： - ）。
这里有代码（LINQPad告诉我它只需要 150ms ，所以这很好）
C:\>net use
New connections will be remembered.
Status Local Remote Network
-------------------------------------------------------------------------------
OK O: \\smarty\Data Microsoft Windows Network
Disconnected P: \\dummy\Data Microsoft Windows Network
OK \\vault2\vault2 Microsoft Windows Network
The command completed successfully.
或者您可能会使用WMI的路线，如this answer至How to ensure network drives are connected for an application?
中提到的那样答案 1 :(得分：7)
在我的项目中，我使用System.IO：
if (Directory.Exists(@"\\hostname\samba-sharename\directory")) { ...
到目前为止它还很快......
答案 2 :(得分：3)
在我的项目中，我必须检查服务器连接是否已建立。我使用 TCP Socket 来异步检查是否可以访问服务器。我想知道你是否可以使用它来检查网络共享。异步TCP套接字连接速度非常快，我在60毫秒内测试连接10次。也许你可以玩一下这个？
编辑：这是我用于项目的异步套接字。使用此类检查某个IP或地址。希望它对你有用
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Net.Sockets;
using System.Net;
using System.Threading;
namespace Base.BaseObjects
{
public class AsynchronousClient
{
#region Properties
private int _port = 0000, currentTry = 0, _buffersize, _fastpingdelay = 80;
private string _server = "localhost";
private Socket client;
private static IPEndPoint remoteEP;
// Delegates & Events
public delegate void SendMessageDelegate(string message);
public event SendMessageDelegate SendMessageEvent;
public delegate void ConnectionStatusDelegate(bool connected, bool reconnect);
public event ConnectionStatusDelegate ConnectionStatusChanged;
// ManualResetEvent instances signal completion.
private static ManualResetEvent connectDone = new ManualResetEvent(false);
private static ManualResetEvent sendDone = new ManualResetEvent(false);
private static ManualResetEvent receiveDone = new ManualResetEvent(false);
/// <summary>
/// Port to monitor
/// </summary>
public int Port { get { return _port; } }
/// <summary>
/// Number of packages to buffer until system reports connection loss
/// </summary>
public int BufferSize { get { return _buffersize; } }
/// <summary>
/// Time in milliseconds between two pings
/// </summary>
public int FastPingDelay { get { return _fastpingdelay; } }
/// <summary>
/// Servername to connect to
/// </summary>
public string Server
{
get { return _server; }
set
{
_server = value;
// Resolve the remote endpoint for the socket.
try
{
IPAddress ipAddress = (IPAddress)Dns.GetHostAddresses(value)[0];
remoteEP = new IPEndPoint(ipAddress, Port);
}
catch (SocketException ex)
{
SendMessage(ex.Message);
}
}
}
#endregion
#region Events & Delegates
protected void SendMessage(string message)
{
if (SendMessageEvent != null)
SendMessageEvent(message);
}
protected void UpdateConnectionStatus(bool connected, bool reconnect)
{
if (ConnectionStatusChanged != null)
ConnectionStatusChanged(connected, reconnect);
}
private void ConnectCallback(IAsyncResult ar)
{
try
{
// Retrieve the socket from the state object.
Socket client = (Socket)ar.AsyncState;
// Complete the connection.
client.EndConnect(ar);
SendMessage(String.Format("Socket connected to {0}", client.RemoteEndPoint.ToString()));
//UpdateConnectionStatus(true, false);
// Signal that the connection has been made.
connectDone.Set();
}
catch (Exception e)
{
SendMessage(e.ToString());
UpdateConnectionStatus(false, true);
}
}
#endregion
#region methods
public AsynchronousClient(int port, string server)
{
_port = port;
Server = server;
_buffersize = 10;
_fastpingdelay = 20;
}
public void CreateSocket()
{
try
{
StopClient();
}
catch (Exception ex)
{
SendMessage(ex.Message);
}
finally
{
client = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
}
}
public bool FastPingSocket()
{
for (currentTry = 0; currentTry <= BufferSize; currentTry++)
{
try
{
CreateSocket();
client.BeginConnect(remoteEP, new AsyncCallback(ConnectCallback), client);
connectDone.WaitOne();
System.Threading.Thread.Sleep(FastPingDelay);
client.Shutdown(SocketShutdown.Receive);
connectDone.WaitOne();
client.Close();
return true;
}
catch (SocketException ex)
{
SendMessage(ex.Message);
}
catch (ObjectDisposedException ex)
{
currentTry--;
SendMessage(ex.Message);
CreateSocket();
}
catch (NullReferenceException ex)
{
currentTry--;
SendMessage(ex.Message);
CreateSocket();
}
catch (ArgumentNullException ex)
{
SendMessage(ex.Message);
CreateSocket();
}
catch (InvalidOperationException ex)
{
SendMessage(ex.Message);
CreateSocket();
currentTry--;
}
finally
{
StopClient();
}
}
UpdateConnectionStatus(false, true);
return false;
}
public void StopClient()
{
// Release the socket.
try
{
client.Shutdown(SocketShutdown.Both);
client.Close();
}
catch (Exception) { }
finally
{
UpdateConnectionStatus(false, false);
}
}
#endregion
}
}
编辑：请不要只是复制/粘贴它。尝试理解代码，以便您可以将其用于您的利益，并根据您的需要对其进行微调。
答案 3 :(得分：2)
我使用上面建议的ping方法，因为我使用的是OpenDNS，所以它对我不起作用 这是一个对我有用的功能：
// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
/// <summary>
/// A quick method to test is the path exists
/// </summary>
/// <param name="s"></param>
/// <param name="timeOutMs"></param>
/// <returns></returns>
public static bool CheckPathExists(string s, int timeOutMs = 120) {
if (s.StartsWith(@"\\")) {
Uri uri = new Uri(s);
if (uri.Segments.Length == 0 || string.IsNullOrWhiteSpace(uri.Host))
return false;
if (uri.Host != Dns.GetHostName()) {
WebRequest request;
WebResponse response;
request = WebRequest.Create(uri);
request.Method = "HEAD";
request.Timeout = timeOutMs;
try {
response = request.GetResponse();
} catch (Exception ex) {
return false;
}
return response.ContentLength > 0;
// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
// Do a Ping to see if the server is there
// This method doesn't work well using OPenDNS since it always succeeds
// regardless if the IP is a valid or not
// OpenDns always maps every host to an IP. If the host is not valid the
// OpenDNS will map it to 67.215.65.132
/* Example:
C:\>ping xxx
Pinging xxx.RT-AC66R [67.215.65.132] with 32 bytes of data:
Reply from 67.215.65.132: bytes=32 time=24ms TTL=55
*/
//Ping pingSender = new Ping();
//PingOptions options = new PingOptions();
// Use the default Ttl value which is 128,
// but change the fragmentation behavior.
//options.DontFragment = true;
// Create a buffer of 32 bytes of data to be transmitted.
//string data = "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa";
//byte[] buffer = Encoding.ASCII.GetBytes(data);
//int timeout = 120;
//PingReply reply = pingSender.Send(uri.Host, timeout, buffer, options);
//if (reply == null || reply.Status != IPStatus.Success)
// return false;
}
}
return File.Exists(s);
}
答案 4 :(得分：1)
这可能是最快的方式，延迟将是一般的网络速度/磁盘访问等。
如果这会导致用户延迟，您可以尝试异步检查吗？
答案 5 :(得分：1)
我最终“作弊”，只是对主机执行ping操作，这很合理，因为实际上我正在检查这种情况。
private bool HostExists(string PCName)
{
Ping pinger = new Ping();
try
{
PingReply reply = pinger.Send(PCName);
return reply.Status == IPStatus.Success;
}
catch
{
return false;
}
finally
{
pinger.Dispose();
}
}
这种方式最适合我，因为它的速度，简单性和可靠性。
答案 6 :(得分：0)
也许您应该尝试创建该文件夹，如果它存在，它将返回您可以捕获的错误。应该没有默认超时。