分享一个C#获取网络链接状态的几种方法

using System;
using System.Web;
using System.Net.Sockets;
using System.Runtime.InteropServices;
using System.Threading;

namespace VvxT.Web
{
public class Internet
{
#region 利用API方式获取网络链接状态
private static int NETWORK_ALIVE_LAN = 0x00000001;
private static int NETWORK_ALIVE_WAN = 0x00000002;
private static int NETWORK_ALIVE_AOL = 0x00000004;

[DllImport("sensapi.dll")]
private extern static bool IsNetworkAlive(ref int flags);
[DllImport("sensapi.dll")]
private extern static bool IsDestinationReachable(string dest, IntPtr ptr);

[DllImport("wininet.dll")]
private extern static bool InternetGetConnectedState(out int connectionDescription, int reservedValue);

public Internet() { }

public static bool IsConnected()
{
int desc = 0;
bool state = InternetGetConnectedState(out desc, 0);
return state;
}

public static bool IsLanAlive()
{
return IsNetworkAlive(ref NETWORK_ALIVE_LAN);
}
public static bool IsWanAlive()
{
return IsNetworkAlive(ref NETWORK_ALIVE_WAN);
}
public static bool IsAOLAlive()
{
return IsNetworkAlive(ref NETWORK_ALIVE_AOL);
}
public static bool IsDestinationAlive(string Destination)
{
return (IsDestinationReachable(Destination, IntPtr.Zero));
}
#endregion

/// <summary>
/// 在指定时间内尝试连接指定主机上的指定端口。 （默认端口：80,默认链接超时：5000毫秒）
/// </summary>
/// <param name="HostNameOrIp">主机名称或者IP地址</param>
/// <param name="port">端口</param>
/// <param name="timeOut">超时时间</param>
/// <returns>返回布尔类型</returns>
public static bool IsHostAlive(string HostNameOrIp, int? port, int? timeOut)
{
TcpClient tc = new TcpClient();
tc.SendTimeout = timeOut ?? 5000;
tc.ReceiveTimeout = timeOut ?? 5000;

bool isAlive;
try
{
tc.Connect(HostNameOrIp, port ?? 80);
isAlive = true;
}
catch
{
isAlive = false;
}
finally
{
tc.Close();
}
return isAlive;
}

}

public class TcpClientConnector
{
/// <summary>
/// 在指定时间内尝试连接指定主机上的指定端口。 （默认端口：80,默认链接超时：5000毫秒）
/// </summary>
/// <param name= "hostname ">要连接到的远程主机的 DNS 名。</param>
/// <param name= "port ">要连接到的远程主机的端口号。 </param>
/// <param name= "millisecondsTimeout ">要等待的毫秒数，或 -1 表示无限期等待。</param>
/// <returns>已连接的一个 TcpClient 实例。</returns>
public static TcpClient Connect(string hostname, int? port, int? millisecondsTimeout)
{
ConnectorState cs = new ConnectorState();
cs.Hostname = hostname;
cs.Port = port ?? 80;
ThreadPool.QueueUserWorkItem(new WaitCallback(ConnectThreaded), cs);
if (cs.Completed.WaitOne(millisecondsTimeout ?? 5000, false))
{
if (cs.TcpClient != null) return cs.TcpClient;
return null;
//throw cs.Exception;
}
else
{
cs.Abort();
return null;
//throw new SocketException(11001); // cannot connect
}
}

private static void ConnectThreaded(object state)
{
ConnectorState cs = (ConnectorState)state;
cs.Thread = Thread.CurrentThread;
try
{
TcpClient tc = new TcpClient(cs.Hostname, cs.Port);
if (cs.Aborted)
{
try { tc.GetStream().Close(); }
catch { }
try { tc.Close(); }
catch { }
}
else
{
cs.TcpClient = tc;
cs.Completed.Set();
}
}
catch (Exception e)
{
cs.Exception = e;
cs.Completed.Set();
}
}

private class ConnectorState
{
public string Hostname;
public int Port;
public volatile Thread Thread;
public readonly ManualResetEvent Completed = new ManualResetEvent(false);
public volatile TcpClient TcpClient;
public volatile Exception Exception;
public volatile bool Aborted;
public void Abort()
{
if (Aborted != true)
{
Aborted = true;
try { Thread.Abort(); }
catch { }
}
}
}
}
}
使用方法：

Default.aspx.cs

Code [http://www.xueit.com]
using System;
using System.Collections.Generic;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Net.Sockets;

namespace VvxT.Web
{
public partial class _Default : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
bool IsConnected = Internet.IsConnected();
bool IsAOLAlive = Internet.IsAOLAlive();

DateTime oldTime1 = DateTime.Now;
bool IsDestinationAlive = Internet.IsDestinationAlive("cn.yahoo.com");
DateTime newTime1 = DateTime.Now;
TimeSpan ts1 = newTime1 - oldTime1;

bool IsLanAlive = Internet.IsLanAlive();
bool IsWanAlive = Internet.IsWanAlive();

DateTime oldTime2 = DateTime.Now;
//bool IsHostAlive = Internet.IsHostAlive("hk.yahoo.com", null, null);//不推荐使用（无法实际控制超时时间）
bool IsHostAlive;
TcpClient tc = TcpClientConnector.Connect("hk.yahoo.com", null, null);//推荐使用（采用线程池强行中断超时时间）
try
{
if (tc != null)
{
tc.GetStream().Close();
tc.Close();
IsHostAlive = true;
}
else
IsHostAlive = false;
}
catch { IsHostAlive = false; }
DateTime newTime2 = DateTime.Now;
TimeSpan ts2 = newTime2 - oldTime2;

Response.Write("Connect：" IsConnected "<br />");
Response.Write("Lan：" IsLanAlive "<br />");
Response.Write("Wan：" IsWanAlive "<br />");
Response.Write("Aol：" IsAOLAlive "<br />");
Response.Write("Sip（cn.yahoo.com）：" IsDestinationAlive " 耗时：" ts1.TotalMilliseconds "<br />");
Response.Write("TcpClient（hk.yahoo.com）：" IsHostAlive " 耗时：" ts2.TotalMilliseconds "<br />");

}
}
}
测试显示效果：

Connect：True
Lan：True
Wan：True
Aol：True
Sip（cn.yahoo.com）：True 耗时：265.625
TcpClient（hk.yahoo.com）：False 耗时：5000

本文部分代码摘自网络，原作者未知，如有冒犯，请给我留言，我会及时更正，谢谢！

此类可用于C/S和B/S结构，以上测试环境为WebApplication。

文章来自学IT网：http://www.xueit.com/html/2011-01/103-1541333311201112102359859.html