c# - TcpClient ConnectAsync 获取状态

Question

有什么方法可以获取 TcpClient 异步连接的状态？使用以下代码，如何使用 Connected 属性获取客户端的状态？我尝试异步建立远程连接，但同时不要等待超过 5 秒 ...

TcpClient client = new TcpClient();

Task tsk = Task.Factory.StartNew(() =>
{
   client.ConnectAsync(host, port);

   // client.Connect   (this is always false)
});

tsk.Wait(5000);

// client.Connect   (or if I use it here, this is always false)

Answer 1

不，@Jon 错了! IsCompleted 只会告诉您任务是否已完成，它不会不表示已建立连接。例如，如果没有服务器在特定地址/端口上打开，IsCompleted 无论如何都会返回 true...您应该检查 IsFaulted。

这是我从互联网上收集的代码，并且我已经测试:

string address = "127.0.0.1";
int port = 8888;
int connectTimeoutMilliseconds = 1000;

var tcpClient = new TcpClient();
var connectionTask = tcpClient
    .ConnectAsync(address, port).ContinueWith(task => {
        return task.IsFaulted ? null : tcpClient;
    }, TaskContinuationOptions.ExecuteSynchronously);
var timeoutTask = Task.Delay(connectTimeoutMilliseconds)
    .ContinueWith<TcpClient>(task => null, TaskContinuationOptions.ExecuteSynchronously);
var resultTask = Task.WhenAny(connectionTask, timeoutTask).Unwrap();

var resultTcpClient = resultTask.GetAwaiter().GetResult();
// Or by using `await`:
// var resultTcpClient = await resultTask.ConfigureAwait(false);

if (resultTcpClient != null)
{
    // Connected!
}
else
{
    // Not connected
}