用C#如何做一个检测网站的URL是否连接正常

首先写一个类

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

namespace Test
{
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

///

/// 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）
///

/// 主机名称或者IP地址
/// 端口
/// 超时时间
/// 返回布尔类型
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;
}
///

/// 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）
///

/// 要连接到的远程主机的 DNS 名。
/// 要连接到的远程主机的端口号。
/// 要等待的毫秒数，或 -1 表示无限期等待。
/// 已连接的一个 TcpClient 实例。
public static TcpClient Connect(string hostname, int? port, int? millisecondsTimeout)
{
try
{
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;
}
else
{
cs.Abort();
return null;
}
}
catch
{
return null;
}
}
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

bool IsHostAlive;//表示是否正常
try
{
TcpClient tc = Internet.Connect("要检测的链接地址", null, 2000); //这里的2000 表示去连接地址2秒 如果2秒内不能访问到 表示认为不正常
//检测网络联通状态
if (tc != null)
{
tc.GetStream().Close();
tc.Close();
IsHostAlive = true;
}
else
{
IsHostAlive = false;
}
}
catch
{
IsHostAlive = false;
}

命名空间
using System;
using System.Collections.Generic;
using System.Windows.Forms;
using System.Diagnostics;
using System.Reflection;
using System.Net.NetworkInformation;
using System.Web;
using System.Net.Sockets;