异步客户端套接字示例

下面的示例程序创建一个连接到服务器的客户端。该客户端是用异步套接字生成的，因此在等待服务器返回响应时不挂起客户端应用程序的执行。该应用程序将字符串发送到服务器，然后在控制台显示该服务器返回的字符串。

 

using System; using System.Net; using System.Net.Sockets; using System.Threading; using System.Text; // State object for receiving data from remote device. public class StateObject { // Client socket. public Socket workSocket = null; // Size of receive buffer. public const int BufferSize = 256; // Receive buffer. public byte[] buffer = new byte[BufferSize]; // Received data string. public StringBuilder sb = new StringBuilder(); } public class AsynchronousClient { // The port number for the remote device. private const int port = 11000; // ManualResetEvent instances signal completion. private static ManualResetEvent connectDone = new ManualResetEvent(false); private static ManualResetEvent sendDone = new ManualResetEvent(false); private static ManualResetEvent receiveDone = new ManualResetEvent(false); // The response from the remote device. private static String response = String.Empty; private static void StartClient() { // Connect to a remote device. try { // Establish the remote endpoint for the socket. // The name of the // remote device is "host.contoso.com". IPHostEntry ipHostInfo = Dns.Resolve("host.contoso.com"); IPAddress ipAddress = ipHostInfo.AddressList[0]; IPEndPoint remoteEP = new IPEndPoint(ipAddress, port); // Create a TCP/IP socket. Socket client = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp); // Connect to the remote endpoint. client.BeginConnect( remoteEP, new AsyncCallback(ConnectCallback), client); connectDone.WaitOne(); // Send test data to the remote device. Send(client,"This is a test<EOF>"); sendDone.WaitOne(); // Receive the response from the remote device. Receive(client); receiveDone.WaitOne(); // Write the response to the console. Console.WriteLine("Response received : {0}", response); // Release the socket. client.Shutdown(SocketShutdown.Both); client.Close(); } catch (Exception e) { Console.WriteLine(e.ToString()); } } private static void ConnectCallback(IAsyncResult ar) { try { // Retrieve the socket from the state object. Socket client = (Socket) ar.AsyncState; // Complete the connection. client.EndConnect(ar); Console.WriteLine("Socket connected to {0}", client.RemoteEndPoint.ToString()); // Signal that the connection has been made. connectDone.Set(); } catch (Exception e) { Console.WriteLine(e.ToString()); } } private static void Receive(Socket client) { try { // Create the state object. StateObject state = new StateObject(); state.workSocket = client; // Begin receiving the data from the remote device. client.BeginReceive( state.buffer, 0, StateObject.BufferSize, 0, new AsyncCallback(ReceiveCallback), state); } catch (Exception e) { Console.WriteLine(e.ToString()); } } private static void ReceiveCallback( IAsyncResult ar ) { try { // Retrieve the state object and the client socket // from the asynchronous state object. StateObject state = (StateObject) ar.AsyncState; Socket client = state.workSocket; // Read data from the remote device. int bytesRead = client.EndReceive(ar); if (bytesRead > 0) { // There might be more data, so store the data received so far. state.sb.Append(Encoding.ASCII.GetString(state.buffer,0,bytesRead)); // Get the rest of the data. client.BeginReceive(state.buffer,0,StateObject.BufferSize,0, new AsyncCallback(ReceiveCallback), state); } else { // All the data has arrived; put it in response. if (state.sb.Length > 1) { response = state.sb.ToString(); } // Signal that all bytes have been received. receiveDone.Set(); } } catch (Exception e) { Console.WriteLine(e.ToString()); } } private static void Send(Socket client, String data) { // Convert the string data to byte data using ASCII encoding. byte[] byteData = Encoding.ASCII.GetBytes(data); // Begin sending the data to the remote device. client.BeginSend(byteData, 0, byteData.Length, 0, new AsyncCallback(SendCallback), client); } private static void SendCallback(IAsyncResult ar) { try { // Retrieve the socket from the state object. Socket client = (Socket) ar.AsyncState; // Complete sending the data to the remote device. int bytesSent = client.EndSend(ar); Console.WriteLine("Sent {0} bytes to server.", bytesSent); // Signal that all bytes have been sent. sendDone.Set(); } catch (Exception e) { Console.WriteLine(e.ToString()); } } public static int Main(String[] args) { StartClient(); return 0; } }