TcpListener Class
Listens for connections from TCP network clients.
For a list of all members of this type, see TcpListener Members.
System.Object
System.Net.Sockets.TcpListener
[Visual Basic] Public Class TcpListener [C#] public class TcpListener [C++] public __gc class TcpListener [JScript] public class TcpListener
Thread Safety
Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.
Remarks
The TcpListener class provides simple methods that listen for and accept incoming connection requests in blocking synchronous mode. You can use either a TcpClient or a Socket to connect with a TcpListener. Create a TcpListener using an IPEndPoint, a Local IP address and port number, or just a port number. Specify Any for the local IP address and 0 for the local port number if you want the underlying service provider to assign those values for you. If you choose to do this, you can use the LocalEndpoint to identify the assigned information.
Use the Start method to begin listening for incoming connection requests. Start will queue incoming connections until you either call the Stop method or it has queued MaxConnections. Use either AcceptSocket or AcceptTcpClient to pull a connection from the incoming connection request queue. These two methods will block. If you want to avoid blocking, you can use the Pending method first to determine if connection requests are available in the queue.
Call the Stop method to close the TcpListener.
Note The Stop method does not close any accepted connections. You are responsible for closing these separately.
Example
[Visual Basic, C#, C++] The following example creates a TcpListener.
[Visual Basic] Imports System Imports System.IO Imports System.Net Imports System.Net.Sockets Imports System.Text Imports Microsoft.VisualBasic Class MyTcpListener Public Shared Sub Main() Try ' Set the TcpListener on port 13000. Dim port As Int32 = 13000 Dim localAddr As IPAddress = IPAddress.Parse("127.0.0.1") Dim server As New TcpListener(localAddr, port) ' Start listening for client requests. server.Start() ' Buffer for reading data Dim bytes(1024) As [Byte] Dim data As [String] = Nothing ' Enter the listening loop. While True Console.Write("Waiting for a connection... ") ' Perform a blocking call to accept requests. ' You could also user server.AcceptSocket() here. Dim client As TcpClient = server.AcceptTcpClient() Console.WriteLine("Connected!") data = Nothing ' Get a stream object for reading and writing Dim stream As NetworkStream = client.GetStream() Dim i As Int32 ' Loop to receive all the data sent by the client. i = stream.Read(bytes, 0, bytes.Length) While (i <> 0) ' Translate data bytes to a ASCII string. data = System.Text.Encoding.ASCII.GetString(bytes, 0, i) Console.WriteLine([String].Format("Received: {0}", data)) ' Process the data sent by the client. data = data.ToUpper() Dim msg As [Byte]() = System.Text.Encoding.ASCII.GetBytes(data) ' Send back a response. stream.Write(msg, 0, msg.Length) Console.WriteLine([String].Format("Sent: {0}", data)) i = stream.Read(bytes, 0, bytes.Length) End While ' Shutdown and end connection client.Close() End While Catch e As SocketException Console.WriteLine("SocketException: {0}", e) End Try Console.WriteLine(ControlChars.Cr + "Hit enter to continue...") Console.Read() End Sub 'Main End Class 'MyTcpListener [C#] using System; using System.IO; using System.Net; using System.Net.Sockets; using System.Text; class MyTcpListener { public static void Main() { try { // Set the TcpListener on port 13000. Int32 port = 13000; IPAddress localAddr = IPAddress.Parse("127.0.0.1"); // TcpListener server = new TcpListener(port); TcpListener server = new TcpListener(localAddr, port); // Start listening for client requests. server.Start(); // Buffer for reading data Byte[] bytes = new Byte[256]; String data = null; // Enter the listening loop. while(true) { Console.Write("Waiting for a connection... "); // Perform a blocking call to accept requests. // You could also user server.AcceptSocket() here. TcpClient client = server.AcceptTcpClient(); Console.WriteLine("Connected!"); data = null; // Get a stream object for reading and writing NetworkStream stream = client.GetStream(); int i; // Loop to receive all the data sent by the client. while((i = stream.Read(bytes, 0, bytes.Length))!=0) { // Translate data bytes to a ASCII string. data = System.Text.Encoding.ASCII.GetString(bytes, 0, i); Console.WriteLine(String.Format("Received: {0}", data)); // Process the data sent by the client. data = data.ToUpper(); byte[] msg = System.Text.Encoding.ASCII.GetBytes(data); // Send back a response. stream.Write(msg, 0, msg.Length); Console.WriteLine(String.Format("Sent: {0}", data)); } // Shutdown and end connection client.Close(); } } catch(SocketException e) { Console.WriteLine("SocketException: {0}", e); } Console.WriteLine("\nHit enter to continue..."); Console.Read(); } } [C++] #using <mscorlib.dll> #using <System.dll> using namespace System; using namespace System::IO; using namespace System::Net; using namespace System::Net::Sockets; using namespace System::Text; void main() { try { // Set the TcpListener on port 13000. Int32 port = 13000; IPAddress* localAddr = IPAddress::Parse(S"127.0.0.1"); // TcpListener* server = new TcpListener(port); TcpListener* server = new TcpListener(localAddr, port); // Start listening for client requests. server->Start(); // Buffer for reading data Byte bytes[] = new Byte[256]; String* data = 0; // Enter the listening loop. while (true) { Console::Write(S"Waiting for a connection... "); // Perform a blocking call to accept requests. // You could also user server.AcceptSocket() here. TcpClient* client = server->AcceptTcpClient(); Console::WriteLine(S"Connected!"); data = 0; // Get a stream Object* for reading and writing NetworkStream* stream = client->GetStream(); Int32 i; // Loop to receive all the data sent by the client. while (i = stream->Read(bytes, 0, bytes->Length)) { // Translate data bytes to a ASCII String*. data = Text::Encoding::ASCII->GetString(bytes, 0, i); Console::WriteLine(String::Format(S"Received: {0}", data)); // Process the data sent by the client. data = data->ToUpper(); Byte msg[] = Text::Encoding::ASCII->GetBytes(data); // Send back a response. stream->Write(msg, 0, msg->Length); Console::WriteLine(String::Format(S"Sent: {0}", data)); } // Shutdown and end connection client->Close(); } } catch (SocketException* e) { Console::WriteLine(S"SocketException: {0}", e); } Console::WriteLine(S"\nHit enter to continue..."); Console::Read(); }
[JScript] No example is available for JScript. To view a Visual Basic, C#, or C++ example, click the Language Filter button
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Requirements
Namespace: System.Net.Sockets
Platforms: Windows 98, Windows NT 4.0, Windows Millennium Edition, Windows 2000, Windows XP Home Edition, Windows XP Professional, Windows Server 2003 family, .NET Compact Framework
Assembly: System (in System.dll)
.NET Framework Security:
- SocketPermission to establish an outgoing connection or accept an incoming request.
See Also
TcpListener Members | System.Net.Sockets Namespace | TcpClient