如何在我的应用程序中不断检查互联网连接，并在连接不可用时作出响应？
目前我正在使用：
while(true) {
if(HasConnection()) {
//doSomething..
}
//stop app by 1sec
}
但似乎相当不优雅。
答案 0 :(得分：3)
超级用户对this question的接受回答描述了Windows确定其是否具有网络访问权限的方式。您可以使用类似的方法，但是当您的应用程序启动时，我会生成一个单独的线程负责进行检查。让单独的线程以您认为最好的方式执行检查，并在连接状态发生变化时引发事件。
答案 1 :(得分：2)
您正在寻找NetworkAvailabilityChanged event。
要检查互联网连接，您可以ping建立一个可靠的网站，例如Google.com。
请注意，无法通知互联网连接中的每次更改（例如ISP中断）。
答案 2 :(得分：2)
使用以下代码：
public static class LocalSystemConnection
{
[DllImport("wininet.dll", SetLastError=true, CallingConvention = CallingConvention.ThisCall)]
extern static bool InternetGetConnectedState(out ConnectionStates lpdwFlags, long dwReserved);
/// <summary>
/// Retrieves the connected state of the local system.
/// </summary>
/// <param name="connectionStates">A <see cref="ConnectionStates"/> value that receives the connection description.</param>
/// <returns>
/// A return value of true indicates that either the modem connection is active, or a LAN connection is active and a proxy is properly configured for the LAN.
/// A return value of false indicates that neither the modem nor the LAN is connected.
/// If false is returned, the <see cref="ConnectionStates.Configured"/> flag may be set to indicate that autodial is configured to "always dial" but is not currently active.
/// If autodial is not configured, the function returns false.
/// </returns>
public static bool IsConnectedToInternet(out ConnectionStates connectionStates)
{
connectionStates = ConnectionStates.Unknown;
return InternetGetConnectedState(out connectionStates, 0);
}
/// <summary>
/// Retrieves the connected state of the local system.
/// </summary>
/// <returns>
/// A return value of true indicates that either the modem connection is active, or a LAN connection is active and a proxy is properly configured for the LAN.
/// A return value of false indicates that neither the modem nor the LAN is connected.
/// If false is returned, the <see cref="ConnectionStates.Configured"/> flag may be set to indicate that autodial is configured to "always dial" but is not currently active.
/// If autodial is not configured, the function returns false.
/// </returns>
public static bool IsConnectedToInternet()
{
ConnectionStates state = ConnectionStates.Unknown;
return IsConnectedToInternet(out state);
}
}
[Flags]
public enum ConnectionStates
{
/// <summary>
/// Unknown state.
/// </summary>
Unknown = 0,
/// <summary>
/// Local system uses a modem to connect to the Internet.
/// </summary>
Modem = 0x1,
/// <summary>
/// Local system uses a local area network to connect to the Internet.
/// </summary>
LAN = 0x2,
/// <summary>
/// Local system uses a proxy server to connect to the Internet.
/// </summary>
Proxy = 0x4,
/// <summary>
/// Local system has RAS (Remote Access Services) installed.
/// </summary>
RasInstalled = 0x10,
/// <summary>
/// Local system is in offline mode.
/// </summary>
Offline = 0x20,
/// <summary>
/// Local system has a valid connection to the Internet, but it might or might not be currently connected.
/// </summary>
Configured = 0x40,
}
答案 3 :(得分：1)
如果您只需要知道是否有至少一个连接可用，您可以尝试：
InternetGetConnectedStateEx（）
http://msdn.microsoft.com/en-us/library/aa384705%28v=vs.85%29.aspx
答案 4 :(得分：1)
如果您要连续检查，请使用计时器
private Timer timer1;
public void InitTimer()
{
timer1 = new Timer();
timer1.Tick += new EventHandler(timerEvent);
timer1.Interval = 2000; // in miliseconds
timer1.Start();
}
private void timerEvent(object sender, EventArgs e)
{
DoSomeThingWithInternet();
}
private void DoSomeThingWithInternet()
{
if (isConnected())
{
// inform user that "you're connected to internet"
}
else
{
// inform user that "you're not connected to internet"
}
}
public static bool isConnected()
{
try
{
using (var client = new WebClient())
using (client.OpenRead("http://clients3.google.com/generate_204"))
{
return true;
}
}
catch
{
return false;
}
}
答案 5 :(得分：0)
您如何知道自己是否有互联网连接？您是否可以将数据包路由到附近的路由器？也许机器只有一个网卡，一个网关，也许网关的连接断开但机器仍然可以路由到网关和本地网络？
也许机器有一个网卡和十几个网关;也许他们总是来去匆匆，但一个总是在吗？
如果机器有多个NIC但只有一个网关怎么办？也许它可以路由到互联网的某个子集，但仍然可以很好地连接到未连接到互联网的本地网络？
如果机器有多个网卡，多个网关，但出于管理政策的原因，仍然只有部分互联网是可路由的，该怎么办？
您是否真的只关心客户是否可以连接您的服务器？
数据包之间可以接受哪种延迟？ （30ms是好的，300ms正在推动人类耐力的极限，3000ms是无法忍受的长时间，960000ms是连接到太阳探测器所需的。）可以接受什么样的丢包？
你真正试图测量什么？
答案 6 :(得分：0)
This将是一个开始，但正如sarnold所提到的，你需要考虑很多事情
答案 7 :(得分：0)
您可以通过ping某个网站来测试互联网连接：
public bool IsConnectedToInternet
{
try
{
using (System.Net.NetworkInformation.Ping ping = new System.Net.NetworkInformation.Ping())
{
string address = @"http://www.google.com";// System.Net.NetworkInformation.PingReply pingReplay = ping.Send(address);//you can specify timeout.
if (pingReplay.Status == System.Net.NetworkInformation.IPStatus.Success)
{
return true;
}
}
}
catch
{
#if DEBUG
System.Diagnostics.Debugger.Break();
#endif//DEBUG
}
return false;
}
答案 8 :(得分：0)
我知道这是一个老问题，但这对我来说很有用。
System.Net.NetworkInformation.NetworkChange.NetworkAvailabilityChanged += NetworkChange_NetworkAvailabilityChanged;
private async void NetworkChange_NetworkAvailabilityChanged(object sender, System.Net.NetworkInformation.NetworkAvailabilityEventArgs e)
{
//code to execute...
}
我将事件订阅给侦听器，并且它会不断检查连接。您可以添加一个If语句，例如：
if (System.Net.NetworkInformation.NetworkInterface.GetIsNetworkAvailable())
{
//Send Ping...
}
else
{
//other code....
}
答案 9 :(得分：0)
此代码将为您挽救生命。.它不仅检查真实的Internet连接，还可以在控制台窗口中指示异常，从而处理异常... 每2秒
using System;
using System.Net;
using System.Threading;
using System.Net.Http;
bool check() //Checking for Internet Connection
{
while (true)
{
try
{ var i = new Ping().Send("www.google.com").Status;
if (i == IPStatus.Success)
{ Console.WriteLine("connected");
return true;
}
else { return false; }
}
catch (Exception)
{
Console.WriteLine("Not Connected");
Thread.Sleep(2000);
continue;
}
}
};
check();
答案 10 :(得分：0)
使用NetworkChange.NetworkAvailabilityChanged是最容易引起误解的答案。它检查网络可用性更改而不是Internet连接更改。
我们可以使用Windows NLM API监视互联网连接。
using System;
using System.Runtime.InteropServices.ComTypes;
using NETWORKLIST;
namespace Components.Network.Helpers
{
public class InternetConnectionChecker : INetworkListManagerEvents, IDisposable
{
private int _cookie;
private IConnectionPoint _connectionPoint;
private readonly INetworkListManager _networkListManager;
public InternetConnectionChecker()
{
_networkListManager = new NetworkListManager();
}
public bool IsConnected()
{
return _networkListManager.IsConnectedToInternet;
}
public void StartMonitoringConnection()
{
try
{
var container = _networkListManager as IConnectionPointContainer;
if (container == null)
throw new Exception("connection container is null");
var riid = typeof(INetworkListManagerEvents).GUID;
container.FindConnectionPoint(ref riid, out _connectionPoint);
_connectionPoint.Advise(this, out _cookie);
}
catch (Exception e)
{
}
}
public void ConnectivityChanged(NLM_CONNECTIVITY newConnectivity)
{
if (_networkListManager.IsConnectedToInternet)
{
// do something based on internet connectivity
}
}
public void Dispose()
{
_connectionPoint.Unadvise(_cookie);
}
}
}