Socket.Connected 屬性

定義

命名空間:

System.Net.Sockets

組件:

System.Net.Sockets.dll

來源:

Socket.cs

取得值，指出上一個 Socket 或 Send 作業是否將 Receive 連接至遠端主機。

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

public bool Connected { get; }

member this.Connected : bool

Public ReadOnly Property Connected As Boolean

屬性值

Boolean

如果最近一次的作業是將 Socket 連接到遠端資源，則為 true，否則，即為 false。

範例

下列程式代碼範例會連線到遠端端點、檢查 Connected 屬性，以及檢查連線的目前狀態。

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

備註

屬性 Connected 會從最後一個 I/O 作業開始取得 的連接 Socket 狀態。 當傳回 false時， Socket 表示從未連接，或已不再連接。 Connected不是安全線程;當 與另一個線程中斷連線時Socket，可能會在中止作業之後傳回 true 。

屬性的值 Connected 會反映連線狀態，如同最近一次的作業一樣。 如果您需要判斷連線的目前狀態，請建立非封鎖、零位元組的 Send 呼叫。 如果呼叫成功傳回或擲回 WAEWOULDBLOCK 錯誤碼， (10035) ，則套接字仍已連線;否則，套接字已不再連線。

如果您在 UDP) 套接字 (使用者數據報通訊協定上呼叫 Connect ，屬性 Connected 一律會傳回 true;不過，此動作不會變更 UDP 固有的無連線本質。