在C#中帶連線逾時功能的TcpClient類（翻譯自MSDN論壇CMF）

關於TcpClient 類在C#中對於操作TCP connection是非常方便的,非常地好！

但是有一點就是，這個類對於CONNECT操作沒有設定逾時！

系統預設的是60秒的逾時，這明顯過於地長。

我們可以重新去用Thread的join這個帶參數的線程，來解決這個問題，下面的這個類就是但連線逾時參數的TCPCliento類

 

the TcpClientWithTimeout.cs class:

using System;using System.Net.Sockets;using System.Threading;/// <summary>/// TcpClientWithTimeout 用來設定一個帶連線逾時功能的類
/// 使用者可以設定毫秒級的等待逾時時間 (1000=1second)/// 例如:/// TcpClient connection = new TcpClientWithTimeout('127.0.0.1',80,1000).Connect();/// </summary>public class TcpClientWithTimeout{  protected string _hostname;  protected int _port;  protected int _timeout_milliseconds;  protected TcpClient connection;  protected bool connected;  protected Exception exception;  public TcpClientWithTimeout(string hostname,int port,int timeout_milliseconds)  {    _hostname = hostname;    _port = port;    _timeout_milliseconds = timeout_milliseconds;  }  public TcpClient Connect()  {    // kick off the thread that tries to connect    connected = false;    exception = null;    Thread thread = new Thread(new ThreadStart(BeginConnect));    thread.IsBackground = true; // 作為後台線程處理
    // 不會佔用機器太長的時間
    thread.Start();    // 等待如下的時間
    thread.Join(_timeout_milliseconds);    if (connected == true)    {      // 如果成功就返回TcpClient對象      thread.Abort();      return connection;    }    if (exception != null)    {      // 如果失敗就拋出錯誤      thread.Abort();      throw exception;    }    else    {      // 同樣地拋出錯誤      thread.Abort();      string message = string.Format("TcpClient connection to {0}:{1} timed out",        _hostname, _port);      throw new TimeoutException(message);    }  }  protected void BeginConnect()  {    try    {      connection = new TcpClient(_hostname, _port);      // 標記成功，返回調用者      connected = true;    }    catch (Exception ex)    {      // 標記失敗      exception = ex;    }  }}

下面的這個例子就是如何利用5秒的逾時，去串連一個網站發送10位元組的資料，並且接收10位元組的資料。

// connect with a 5 second timeout on the connection
TcpClient connection = new TcpClientWithTimeout("www.google.com", 80, 5000).Connect();
NetworkStream stream = connection.GetStream();

// Send 10 bytes
byte[] to_send = {0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0xa};
stream.Write(to_send, 0, to_send.Length);

// Receive 10 bytes
byte[] readbuf = new byte[10]; // you must allocate space first
stream.ReadTimeout = 10000; // 10 second timeout on the read
stream.Read(readbuf, 0, 10); // read

// Disconnect nicely
stream.Close();      // workaround for a .net bug: http://support.microsoft.com/kb/821625
connection.Close();