TcpListener.Pending 方法

定义

命名空间:

System.Net.Sockets

程序集:

System.Net.Sockets.dll

程序集:

System.dll

程序集:

netstandard.dll

确定是否有挂起的连接请求。

public:
 bool Pending();

public bool Pending ();

member this.Pending : unit -> bool

Public Function Pending () As Boolean

返回

Boolean

如果连接正挂起，则为 true；否则为 false。

例外

InvalidOperationException

尚未通过调用 Start() 来启动该侦听器。

示例

下面的代码示例检查 Pending 方法。 如果连接请求正在等待接受，则会 AcceptTcpClient 调用该方法。

try
{
   // Use the Pending method to poll the underlying socket instance for client connection requests.
   TcpListener^ tcpListener = gcnew TcpListener( portNumber );
   tcpListener->Start();

   if ( !tcpListener->Pending() )
   {
      Console::WriteLine( "Sorry, no connection requests have arrived" );
   }
   else
   {
      //Accept the pending client connection and return a TcpClient object^ initialized for communication.
      TcpClient^ tcpClient = tcpListener->AcceptTcpClient();
      
      // Using the RemoteEndPoint property.
      Console::WriteLine( "I am listening for connections on {0} on port number {1}",
         IPAddress::Parse( ( (IPEndPoint^)(tcpListener->LocalEndpoint) )->Address->ToString() ),
         ( (IPEndPoint^)(tcpListener->LocalEndpoint) )->Port );

const int portNumber = 13;

try
{
    // Use the Pending method to poll the underlying socket instance for client connection requests.
    IPAddress ipAddress = Dns.Resolve("localhost").AddressList[0];
    TcpListener tcpListener = new TcpListener(ipAddress, portNumber);
    tcpListener.Start();

    if (!tcpListener.Pending())
    {
        Console.WriteLine("Sorry, no connection requests have arrived");
    }
    else
    {
        //Accept the pending client connection and return a TcpClient object initialized for communication.
        TcpClient tcpClient = tcpListener.AcceptTcpClient();
        // Using the RemoteEndPoint property.
        Console.WriteLine("I am listening for connections on " +
            IPAddress.Parse(((IPEndPoint)tcpListener.LocalEndpoint).Address.ToString()) +
            "on port number " + ((IPEndPoint)tcpListener.LocalEndpoint).Port.ToString());

        //Close the tcpListener and tcpClient instances
        tcpClient.Close();
    }

    tcpListener.Stop();
}
catch (Exception e)
{
    Console.WriteLine(e.ToString());
}

Try

   Dim ipAddress As IPAddress = Dns.Resolve("localhost").AddressList(0)
  Dim tcpListener As New TcpListener(ipAddress, portNumber)
  tcpListener.Start()
  
   ' Use the Pending method to poll the underlying socket instance for client connection requests.
   If Not tcpListener.Pending() Then
      
      Console.WriteLine("Sorry, no connection requests have arrived")
   
   Else
      
      'Accept the pending client connection and return a TcpClient object initialized for communication.
      Dim tcpClient As TcpClient = tcpListener.AcceptTcpClient()
      ' Using the RemoteEndPoint property.
      Console.Write("I am listening for connections on ")
      Console.Writeline(IPAddress.Parse(CType(tcpListener.LocalEndpoint, IPEndPoint).Address.ToString())) 
      Console.Write("on port number ")
      Console.Write(CType(tcpListener.LocalEndpoint, IPEndPoint).Port.ToString())

注解

此非阻塞方法确定是否存在任何挂起的连接请求。 AcceptSocket由于该方法AcceptTcpClient在方法排队传入连接请求之前Start阻止执行，Pending因此该方法可用于确定连接是否可用，然后再尝试接受这些连接。

另请参阅

• Start()
• AcceptSocket()
• AcceptTcpClient()