Socket.Connected 属性

定义

命名空间:

System.Net.Sockets

程序集:

System.Net.Sockets.dll

Source:

Socket.cs

获取一个值，该值指示 Socket 是在上次 Send 还是 Receive 操作时连接到远程主机。

public:
 property bool Connected { bool get(); };

public bool Connected { get; }

member this.Connected : bool

Public ReadOnly Property Connected As Boolean

属性值

Boolean

如果 Socket 在最近操作时连接到远程资源，则为 true；否则为 false。

示例

下面的代码示例连接到远程终结点，检查 Connected 属性，并检查连接的当前状态。

client->Connect( anEndPoint );
if (  !client->Connected )
{
   Console::WriteLine( "Winsock error: {0}", Convert::ToString(
      System::Runtime::InteropServices::Marshal::GetLastWin32Error() ) );
}
   
// This is how you can determine whether a socket is still connected.
bool blockingState = client->Blocking;
try
{
   array<Byte>^tmp = gcnew array<Byte>(1);
   client->Blocking = false;
   client->Send( tmp, 0, static_cast<SocketFlags>(0) );
   Console::WriteLine( L"Connected!" );
}
catch ( SocketException^ e ) 
{
   // 10035 == WSAEWOULDBLOCK
   if ( e->NativeErrorCode.Equals( 10035 ) )
   {
      Console::WriteLine( "Connected from an exception!" );
   }
   else
   {
      Console::WriteLine( "Disconnected: {0}!", e->NativeErrorCode );
   }
}
finally
{
   client->Blocking = blockingState;
}

Console::WriteLine( "Connected: {0}", client->Connected );

// .Connect throws an exception if unsuccessful
client.Connect(anEndPoint);

// This is how you can determine whether a socket is still connected.
bool blockingState = client.Blocking;
try
{
    byte [] tmp = new byte[1];

    client.Blocking = false;
    client.Send(tmp, 0, 0);
    Console.WriteLine("Connected!");
}
catch (SocketException e)
{
    // 10035 == WSAEWOULDBLOCK
    if (e.NativeErrorCode.Equals(10035))
    {
        Console.WriteLine("Still Connected, but the Send would block");
    }
    else
    {
        Console.WriteLine("Disconnected: error code {0}!", e.NativeErrorCode);
    }
}
finally
{
    client.Blocking = blockingState;
}

Console.WriteLine("Connected: {0}", client.Connected);

    ' .Connect throws an exception if unsuccessful
    client.Connect(anEndPoint)
    
    ' This is how you can determine whether a socket is still connected.
    Dim blockingState As Boolean = client.Blocking
    Try
        Dim tmp(0) As Byte
        
        client.Blocking = False
        client.Send(tmp, 0, 0)
        Console.WriteLine("Connected!")
    Catch e As SocketException
        ' 10035 == WSAEWOULDBLOCK
        If e.NativeErrorCode.Equals(10035) Then
            Console.WriteLine("Still Connected, but the Send would block")
        Else
            Console.WriteLine("Disconnected: error code {0}!", e.NativeErrorCode)
        End If
    Finally
        client.Blocking = blockingState
    End Try
    
    Console.WriteLine("Connected: {0}", client.Connected)

End Sub

注解

属性 Connected 获取自上次 I/O 操作起的连接状态 Socket 。 当它返回 false时， Socket 要么从未连接，要么不再连接。 Connected不是线程安全;当 从另一个线程断开连接时，操作中止后，Socket它可能会返回 true 。

属性的值 Connected 反映自最近操作起的连接状态。 如果需要确定连接的当前状态，请进行非阻止的零字节发送调用。 如果调用成功返回或引发 WAEWOULDBLOCK 错误代码 (10035) ，则套接字仍处于连接状态;否则，套接字不再连接。

如果在 UDP) 套接字 (用户数据报协议上调用 Connect ，则 Connected 属性始终返回 true;但是，此操作不会更改 UDP 固有的无连接性质。