TCP斷開重連

     在TCP協議中，對於斷開的一方其本地用來通訊的端口（系統分配的）仍然會被保留一段時間。所以客戶端斷開后立即再連就是失敗。解決的途徑就是換一個本地的通訊端口，由於不能手動指定一個新端口那就只能重新創建TcpClient實例。

在重新創建TcpClient之前要釋放掉原TcpClient所占有的資源。

   C#代碼：

    

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Net.Sockets;
using System.Threading;

namespace OnLineVideo.Util
{
    public class SocketClient
    {

        private TcpClient client;
        private bool isConnection=false;
        private string hostip;//TCP服務器
        private int port;//端口
        //檢查網絡狀態線程
        Thread checkStateThread;
        
        public SocketClient(string hostip, int port)
        {
            this.hostip = hostip;
            this.port = port;

            client = new TcpClient();
            try
            {
                client.Connect(hostip, port);
            }
            catch
            {
                IsConnection = false;
            }
            checkStateThread = new Thread(new ThreadStart(checkState));
            checkStateThread.IsBackground = true;
            checkStateThread.Start();
        }
        /// <summary>
        /// 獲取或者設置網絡連接狀態
        /// </summary>
        public bool IsConnection
        {
            get { return isConnection;}
            set { isConnection = value; }
        }
        private void checkState()
        {
            while (true)
            {
                Thread.Sleep(1000);
                if (client.Connected== false)
                {
                    try
                    {
                        client.Close();
                        client = new TcpClient();
                        client.Connect(hostip, port);
                        IsConnection = true;
                    }
                    catch
                    {
                        IsConnection = false;
                    }
                }

            }
        }
        public void SendCommand(string strMessage)
        {
            try
            {
                byte[] bytesArray = Encoding.ASCII.GetBytes(strMessage+"\n");
                NetworkStream networkStream = client.GetStream();
                networkStream.Write(bytesArray,0,bytesArray.Length);
            }catch
            {
                IsConnection = false;
            }
        }
        public void Close()
        {
            client.Close();
        }  
    }
}