一、网上常用方法
1、当Socket.Conneted == false时,调用如下函数进行判断
点击(此处)折叠或打开
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///
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/// 当socket.connected为false时,进一步确定下当前连接状态
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///
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///
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private bool IsSocketConnected()
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{
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#region remarks
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/********************************************************************************************
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* 当Socket.Conneted为false时, 如果您需要确定连接的当前状态,请进行非阻塞、零字节的 Send 调用。
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* 如果该调用成功返回或引发 WAEWOULDBLOCK 错误代码 (10035),则该套接字仍然处于连接状态;
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* 否则,该套接字不再处于连接状态。
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* Depending on
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********************************************************************************************/
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#endregion
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#region 过程
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// This is how you can determine whether a socket is still connected.
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bool connectState = true;
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bool blockingState = socket.Blocking;
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try
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{
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byte[] tmp = new byte[1];
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socket.Blocking = false;
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socket.Send(tmp, 0, 0);
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//Console.WriteLine("Connected!");
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connectState = true; //若Send错误会跳去执行catch体,而不会执行其try体里其之后的代码
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}
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catch (SocketException e)
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{
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// 10035 == WSAEWOULDBLOCK
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if (e.NativeErrorCode.Equals(10035))
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{
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//Console.WriteLine("Still Connected, but the Send would block");
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connectState = true;
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}
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else
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{
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//Console.WriteLine("Disconnected: error code {0}!", e.NativeErrorCode);
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connectState = false;
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}
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}
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finally
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{
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socket.Blocking = blockingState;
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}
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//Console.WriteLine("Connected: {0}", client.Connected);
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return connectState;
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#endregion
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}
2、根据socket.poll判断
点击(此处)折叠或打开
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///
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/// 另一种判断connected的方法,但未检测对端网线断开或ungraceful的情况
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///
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///
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///
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static bool IsSocketConnected(Socket s)
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{
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#region remarks
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/* As zendar wrote, it is nice to use the Socket.Poll and Socket.Available, but you need to take into conside ration
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* that the socket might not have been initialized in the first place.
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* This is the last (I believe) piece of information and it is supplied by the Socket.Connected property.
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* The revised version of the method would looks something like this:
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* from: */
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#endregion
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#region 过程
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return !((s.Poll(1000, SelectMode.SelectRead) && (s.Available == 0)) || !s.Connected);
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/* The long, but simpler-to-understand version:
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bool part1 = s.Poll(1000, SelectMode.SelectRead);
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bool part2 = (s.Available == 0);
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if ((part1 && part2 ) || !s.Connected)
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return false;
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else
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return true;
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*/
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#endregion
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}
总结:--1--此两种方法出处可在函数体中的remark中找到链接
--2--此两种方法适用于对端正常关闭socket下的本地socket状态检测,在非正常关闭如断电、拔网线的情况下不起作用
因为Socket.Conneted存在bug,详见
二、支持物理断线重连功能的类
利用BeginReceive + KeepAlive实现物理断线重连,初步测验了一下,正常。(部分代码参考及
blog在C#中利用keep-alive处理socket网络异常断开)
Keep-Alive机制的介绍请看
以此备忘,同时希望能帮助到有需要的同学。
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using System;
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using System.Collections.Generic;
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using System.Linq;
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using System.Text;
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using System.Net.Sockets;
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using System.Net;
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using System.Threading;
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namespace MySocket
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{
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public class Socket_wrapper
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{
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//委托
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private delegate void delSocketDataArrival(byte[] data);
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static delSocketDataArrival socketDataArrival = socketDataArrivalHandler;
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private delegate void delSocketDisconnected();
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static delSocketDisconnected socketDisconnected = socketDisconnectedHandler;
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public static Socket theSocket = null;
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private static string remoteHost = "192.168.1.71";
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private static int remotePort = 6666;
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private static String SockErrorStr = null;
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private static ManualResetEvent TimeoutObject = new ManualResetEvent(false);
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private static Boolean IsconnectSuccess = false; //异步连接情况,由异步连接回调函数置位
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private static object lockObj_IsConnectSuccess = new object();
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///
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/// 构造函数
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///
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///
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///
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public Socket_wrapper(string strIp, int iPort)
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{
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remoteHost = strIp;
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remotePort = iPort;
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}
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///
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/// 设置心跳
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///
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private static void SetXinTiao()
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{
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//byte[] inValue = new byte[] { 1, 0, 0, 0, 0x20, 0x4e, 0, 0, 0xd0, 0x07, 0, 0 };// 首次探测时间20 秒, 间隔侦测时间2 秒
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byte[] inValue = new byte[] { 1, 0, 0, 0, 0x88, 0x13, 0, 0, 0xd0, 0x07, 0, 0 };// 首次探测时间5 秒, 间隔侦测时间2 秒
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theSocket.IOControl(IOControlCode.KeepAliveValues, inValue, null);
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}
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///
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/// 创建套接字+异步连接函数
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///
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///
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private static bool socket_create_connect()
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{
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IPAddress ipAddress = IPAddress.Parse(remoteHost);
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IPEndPoint remoteEP = new IPEndPoint(ipAddress, remotePort);
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theSocket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
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theSocket.SendTimeout = 1000;
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SetXinTiao();//设置心跳参数
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#region 异步连接代码
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TimeoutObject.Reset(); //复位timeout事件
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try
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{
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theSocket.BeginConnect(remoteEP, connectedCallback, theSocket);
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}
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catch (Exception err)
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{
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SockErrorStr = err.ToString();
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return false;
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}
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if (TimeoutObject.WaitOne(10000, false))//直到timeout,或者TimeoutObject.set()
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{
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if (IsconnectSuccess)
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{
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return true;
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}
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else
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{
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return false;
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}
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}
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else
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{
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SockErrorStr = "Time Out";
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return false;
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}
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#endregion
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}
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///
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/// 同步receive函数
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///
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///
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///
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public string socket_receive(byte[] readBuffer)
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{
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try
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{
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if (theSocket == null)
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{
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socket_create_connect();
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}
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else if (!theSocket.Connected)
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{
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if (!IsSocketConnected())
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Reconnect();
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}
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int bytesRec = theSocket.Receive(readBuffer);
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if (bytesRec == 0)
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{
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//warning 0 bytes received
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}
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return Encoding.ASCII.GetString(readBuffer, 0, bytesRec);
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}
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catch (SocketException se)
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{
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//print se.ErrorCode
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throw;
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}
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}
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///
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/// 同步send函数
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///
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///
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///
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public bool socket_send(string sendMessage)
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{
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if (checkSocketState())
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{
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return SendData(sendMessage);
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}
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return false;
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}
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///
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/// 断线重连函数
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///
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///
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private static bool Reconnect()
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{
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//关闭socket
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theSocket.Shutdown(SocketShutdown.Both);
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theSocket.Disconnect(true);
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IsconnectSuccess = false;
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theSocket.Close();
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//创建socket
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return socket_create_connect();
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}
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///
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/// 当socket.connected为false时,进一步确定下当前连接状态
-
///
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///
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private bool IsSocketConnected()
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{
-
#region remarks
-
/********************************************************************************************
-
* 当Socket.Conneted为false时, 如果您需要确定连接的当前状态,请进行非阻塞、零字节的 Send 调用。
-
* 如果该调用成功返回或引发 WAEWOULDBLOCK 错误代码 (10035),则该套接字仍然处于连接状态;
-
* 否则,该套接字不再处于连接状态。
-
* Depending on
-
********************************************************************************************/
-
#endregion
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#region 过程
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// This is how you can determine whether a socket is still connected.
-
bool connectState = true;
-
bool blockingState = theSocket.Blocking;
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try
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{
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byte[] tmp = new byte[1];
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theSocket.Blocking = false;
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theSocket.Send(tmp, 0, 0);
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//Console.WriteLine("Connected!");
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connectState = true; //若Send错误会跳去执行catch体,而不会执行其try体里其之后的代码
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}
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catch (SocketException e)
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{
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// 10035 == WSAEWOULDBLOCK
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if (e.NativeErrorCode.Equals(10035))
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{
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//Console.WriteLine("Still Connected, but the Send would block");
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connectState = true;
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}
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else
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{
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//Console.WriteLine("Disconnected: error code {0}!", e.NativeErrorCode);
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connectState = false;
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}
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}
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finally
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{
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theSocket.Blocking = blockingState;
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}
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//Console.WriteLine("Connected: {0}", client.Connected);
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return connectState;
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#endregion
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}
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///
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/// 另一种判断connected的方法,但未检测对端网线断开或ungraceful的情况
-
///
-
///
-
///
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public static bool IsSocketConnected(Socket s)
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{
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#region remarks
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/* As zendar wrote, it is nice to use the Socket.Poll and Socket.Available, but you need to take into consideration
-
* that the socket might not have been initialized in the first place.
-
* This is the last (I believe) piece of information and it is supplied by the Socket.Connected property.
-
* The revised version of the method would looks something like this:
-
* from: */
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#endregion
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#region 过程
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if (s == null)
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return false;
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return !((s.Poll(1000, SelectMode.SelectRead) && (s.Available == 0)) || !s.Connected);
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/* The long, but simpler-to-understand version:
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bool part1 = s.Poll(1000, SelectMode.SelectRead);
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bool part2 = (s.Available == 0);
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if ((part1 && part2 ) || !s.Connected)
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return false;
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else
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return true;
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*/
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#endregion
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}
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///
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/// 异步连接回调函数
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///
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///
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static void connectedCallback(IAsyncResult iar)
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{
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#region <remarks>
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/// 1、置位IsconnectSuccess
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#endregion </remarks>
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lock (lockObj_IsConnectSuccess)
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{
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Socket client = (Socket)iar.AsyncState;
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try
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{
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client.EndConnect(iar);
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IsconnectSuccess = true;
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StartKeepAlive(); //开始KeppAlive检测
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}
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catch (Exception e)
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{
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//Console.WriteLine(e.ToString());
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SockErrorStr = e.ToString();
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IsconnectSuccess = false;
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}
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finally
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{
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TimeoutObject.Set();
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}
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}
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}
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///
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/// 开始KeepAlive检测函数
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///
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private static void StartKeepAlive()
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{
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theSocket.BeginReceive(buffer, 0, buffer.Length, SocketFlags.None, new AsyncCallback(OnReceiveCallback), theSocket);
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}
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///
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/// BeginReceive回调函数
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///
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static byte[] buffer = new byte[1024];
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private static void OnReceiveCallback(IAsyncResult ar)
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{
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try
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{
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Socket peerSock = (Socket)ar.AsyncState;
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int BytesRead = peerSock.EndReceive(ar);
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if (BytesRead > 0)
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{
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byte[] tmp = new byte[BytesRead];
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Array.ConstrainedCopy(buffer, 0, tmp, 0, BytesRead);
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if (socketDataArrival != null)
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{
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socketDataArrival(tmp);
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}
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}
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else//对端gracefully关闭一个连接
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{
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if (theSocket.Connected)//上次socket的状态
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{
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if (socketDisconnected != null)
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{
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//1-重连
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socketDisconnected();
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//2-退出,不再执行BeginReceive
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return;
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}
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}
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}
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//此处buffer似乎要清空--待实现 zq
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theSocket.BeginReceive(buffer, 0, buffer.Length, SocketFlags.None, new AsyncCallback(OnReceiveCallback), theSocket);
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}
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catch (Exception ex)
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{
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if (socketDisconnected != null)
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{
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socketDisconnected(); //Keepalive检测网线断开引发的异常在这里捕获
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return;
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}
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}
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}
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///
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/// 异步收到消息处理器
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///
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///
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private static void socketDataArrivalHandler(byte[] data)
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{
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}
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///
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/// socket由于连接中断(软/硬中断)的后续工作处理器
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///
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private static void socketDisconnectedHandler()
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{
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Reconnect();
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}
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///
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/// 检测socket的状态
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///
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///
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public static bool checkSocketState()
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{
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try
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{
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if (theSocket == null)
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{
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return socket_create_connect();
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}
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else if (IsconnectSuccess)
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{
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return true;
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}
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else//已创建套接字,但未connected
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{
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#region 异步连接代码
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TimeoutObject.Reset(); //复位timeout事件
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try
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{
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IPAddress ipAddress = IPAddress.Parse(remoteHost);
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IPEndPoint remoteEP = new IPEndPoint(ipAddress, remotePort);
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theSocket.BeginConnect(remoteEP, connectedCallback, theSocket);
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SetXinTiao();//设置心跳参数
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}
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catch (Exception err)
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{
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SockErrorStr = err.ToString();
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return false;
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}
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if (TimeoutObject.WaitOne(2000, false))//直到timeout,或者TimeoutObject.set()
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{
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if (IsconnectSuccess)
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{
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return true;
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}
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else
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{
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return false;
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}
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}
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else
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{
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SockErrorStr = "Time Out";
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return false;
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}
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#endregion
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}
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}
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catch (SocketException se)
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{
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SockErrorStr = se.ToString();
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return false;
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}
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}
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///
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/// 同步发送
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///
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///
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///
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public static bool SendData(string dataStr)
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{
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bool result = false;
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if (dataStr == null || dataStr.Length < 0)
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return result;
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try
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{
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byte[] cmd = Encoding.Default.GetBytes(dataStr);
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int n = theSocket.Send(cmd);
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if (n < 1)
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result = false;
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}
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catch (Exception ee)
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{
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SockErrorStr = ee.ToString();
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result = false;
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}
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return result;
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}
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}
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}
三、源码下载
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