C#网络通信代码——点对点,点对多,同步,异步 on UDP/TCP

hf9881

贡献于2013-09-04

字数:30174 关键词: .NET开发 C#

C#网络通信代码——点对点,点对多,同步,异步 on UDP/TCP 注:本文不适用于因特网打洞通信(点对点模式),涉及的对点通信只能在局域网内实现。若要实现公网范围内的因特网通信(P2P ),请使用公网服务器来实现打洞或信息转发。 更多内容,请搜索“NAT 打洞”。 //C# code:UDP服务器端 namespace UDPServer {     class Program     {         static void Main(string[] args)         {             int recv;             byte[] data = new byte[1024];             //构建TCP 服务器             //得到本机IP,设置TCP端口号                      IPEndPoint ipep = new IPEndPoint(IPAddress.Any , 8001);             Socket newsock = new Socket(AddressFamily.InterNetwork, SocketType.Dgram , ProtocolType.Udp);             //绑定网络地址             newsock.Bind(ipep);             Console.WriteLine("This is a Server, host name is {0}",Dns.GetHostName());             //等待客户机连接             Console.WriteLine("Waiting for a client...");             //得到客户机IP             IPEndPoint sender = new IPEndPoint(IPAddress.Any, 0);             EndPoint Remote = (EndPoint)(sender);             recv = newsock.ReceiveFrom(data, ref Remote);             Console .WriteLine ("Message received from {0}: ", Remote.ToString ());             Console .WriteLine (Encoding .ASCII .GetString (data ,0,recv ));             //客户机连接成功后,发送欢迎信息             string welcome = "Welcome ! ";             //字符串与字节数组相互转换             data  = Encoding .ASCII .GetBytes (welcome );             //发送信息             newsock .SendTo (data ,data.Length ,SocketFlags .None ,Remote );             while (true )             {                 data =new byte [1024];                 //发送接受信息                 recv =newsock.ReceiveFrom(data ,ref Remote);                 Console .WriteLine (Encoding .ASCII .GetString (data ,0,recv));                 newsock .SendTo (data ,recv ,SocketFlags .None ,Remote );             }         }         } } //C# code:UDP客户端 using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Net; using System.Net.Sockets; namespace UDPClient {     class Program     {         static void Main(string[] args)         {             byte[] data = new byte[1024];             string input ,stringData;             //构建TCP 服务器             Console.WriteLine("This is a Client, host name is {0}", Dns.GetHostName());             //设置服务IP,设置TCP端口号             IPEndPoint ipep = new IPEndPoint(IPAddress .Parse ("127.0.0.1") , 8001);             //定义网络类型,数据连接类型和网络协议UDP             Socket server = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp);             string welcome = "Hello! ";              data = Encoding.ASCII.GetBytes(welcome);             server.SendTo(data, data.Length, SocketFlags.None, ipep);             IPEndPoint sender = new IPEndPoint(IPAddress.Any, 0);             EndPoint Remote = (EndPoint)sender;             data = new byte[1024];             int recv = server.ReceiveFrom(data, ref Remote);             Console.WriteLine("Message received from {0}: ", Remote.ToString());             Console.WriteLine(Encoding .ASCII .GetString (data,0,recv));             while (true)             {                 input = Console .ReadLine ();                 if (input =="exit")                     break ;                 server .SendTo (Encoding .ASCII .GetBytes (input ),Remote );                 data = new byte [1024];                 recv = server.ReceiveFrom(data, ref Remote);                 stringData = Encoding.ASCII.GetString(data, 0, recv);                 Console.WriteLine(stringData);             }             Console .WriteLine ("Stopping Client.");             server .Close ();                     }         }     } //C# code:TCP客户端 //TCPClient 类提供了一种使用 TCP 协议连接到某个端点的简化方法。它还通过 //NetworkStream 对象展现在连接过程中读取或写入的数据。请参见下面从 //QuickStart 文档中摘录的日期/时间客户机示例。 using System; using System.Net; using System.Net.Sockets; using System.IO; using System.Text; class Client { public static void Main(String[] args) { TCPClient tcpc = new TCPClient(); Byte[] read = new Byte[32]; if (args.Length != 1) { Console.WriteLine(“请在命令行中指定服务器名称”); return; } String server = args[0]; // 验证服务器是否存在 if (DNS.GetHostByName(server) == null) { Console.WriteLine(“找不到服务器:” + 服务器); return; } // 尝试连接到服务器 if (tcpc.Connect(server, 13) == -1) { Console.WriteLine(“无法连接到服务器:” + 服务器); return; } // 获取流 Stream s = tcpc.GetStream(); // 读取流并将它转换为 ASCII 码形式 int bytes = s.Read(read, 0, read.Length); String Time = Encoding.ASCII.GetString(read); // 显示数据 Console.WriteLine(“已接收到的” + 字节 + “字节”); Console.WriteLine(“当前日期和时间是:” + 时间); tcpc.Close(); } } //TCPListener //TCPListener 类便于在来自某个客户机的 TCP 连接的特定套接字上进行侦听的工作。//请参见下面包括在 QuickStart 文档中的日期/时间服务器示例。 using System; using System.Net; using System.Net.Sockets; using System.Text; class Server { public static void Main() { DateTime now; String strDateLine; Encoding ASCII = Encoding.ASCII; // 在端口 13 进行侦听 TCPListener tcpl = new TCPListener(13); tcpl.Start(); Console.WriteLine(“正在等待客户进行连接”); Console.WriteLine(“请按 Ctrl+c 退出...”); while (true) { // 接收会阻塞,直到有人连接上 Socket s = tcpl.Accept(); // 获取当前的日期和时间并将它连接成一个字符串 now = DateTime.Now; strDateLine = now.ToShortDateString() + " " + now.ToLongTimeString(); // 将该字符串转换成一个字节数组并发送它 Byte[] byteDateLine = ASCII.GetBytes(strDateLine.ToCharArray()); s.Send(byteDateLine, byteDateLine.Length, 0); Console.WriteLine(“发送” + strDateLine); } } } #region "Download: File transfer FROM ftp server"          ///           /// Copy a file from FTP server to local          ///           /// Target filename, if required           /// Full path of the local file           ///           /// Target can be blank (use same filename), or just a filename          /// (assumes current directory) or a full path and filename           public bool Download(string sourceFilename, string localFilename, bool PermitOverwrite)          {              //2. determine target file              FileInfo fi = new FileInfo(localFilename);              return this.Download(sourceFilename, fi, PermitOverwrite);          }          //Version taking an FtpFileInfo          public bool Download(FtpFileInfo file, string localFilename, bool permitOverwrite)          {              return this.Download(file.FullName, localFilename, permitOverwrite);          }          //Another version taking FtpFileInfo and FileInfo          public bool Download(FtpFileInfo file, FileInfo localFI, bool permitOverwrite)          {              return this.Download(file.FullName, localFI, permitOverwrite);          }          //Version taking string/FileInfo          public bool Download(string sourceFilename, FileInfo targetFI, bool permitOverwrite)          {              //1. check target              if (targetFI.Exists && !(permitOverwrite))              {                  throw (new ApplicationException("Target file already exists"));              }              //2. check source              string target;              if (sourceFilename.Trim() == "")              {                  throw (new ApplicationException("File not specified"));              }              else if (sourceFilename.Contains("/"))              {                  //treat as a full path                  target = AdjustDir(sourceFilename);              }              else              {                  //treat as filename only, use current directory                  target = CurrentDirectory + sourceFilename;              }              string URI = Hostname + target;              //3. perform copy              System.Net.FtpWebRequest ftp = GetRequest(URI);              //Set request to download a file in binary mode              ftp.Method = System.Net.WebRequestMethods.Ftp.DownloadFile;              ftp.UseBinary = true;              //open request and get response stream              using (FtpWebResponse response = (FtpWebResponse)ftp.GetResponse())              {                  using (Stream responseStream = response.GetResponseStream())                  {                      //loop to read & write to file                      using (FileStream fs = targetFI.OpenWrite())                      {                          try                          {                              byte[] buffer = new byte[2048];                              int read = 0;                              do                              {                                  read = responseStream.Read(buffer, 0, buffer.Length);                                  fs.Write(buffer, 0, read);                              } while (!(read == 0));                              responseStream.Close();                              fs.Flush();                              fs.Close();                          }                          catch (Exception)                          {                              //catch error and delete file only partially downloaded                              fs.Close();                              //delete target file as it's incomplete                              targetFI.Delete();                              throw;                          }                      }                      responseStream.Close();                  }                  response.Close();              }              return true;          }          #endregion //简单的UDP收发.  //发送  //C# code try {     Socket s = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp);  //向此网段发广播包     int UDPListenerPort = 8082;     IPAddress broadcast = IPAddress.Parse("192.168.0.255"); //此处根据IP及子网掩码改为相应的广播IP      string ts = "This is UPD string for sending";      byte[] sendbuf = Encoding.ASCII.GetBytes(ts);      IPEndPoint ep = new IPEndPoint(broadcast, UDPListenerPort);      s.SendTo(sendbuf, ep);   }    catch (Exception e)  {} //接收  //C# code // UdpClient listener; int UDPListenerPort = 8082; IPEndPoint groupEP = new IPEndPoint(IPAddress.Any, UDPListenerPort); try {     while (true)     {         byte[] bytes = listener.Receive(ref groupEP);         string RecIP = groupEP.ToString().Substring(0, groupEP.ToString().IndexOf(":"));  //收到发送UPD端的IP         string RecStr = Encoding.ASCII.GetString(bytes, 0, bytes.Length);   //收到的UPD字符串      } }    catch {} //C# code ,TCPClient  //使用Remoting:  //C# code using System;  namespace Remotable  {      public class RemotableType : MarshalByRefObject      {          private string _internalString = "This is the RemotableType.";          public string StringMethod()          {              return _internalString;          }      }  }  using System;  using System.Runtime.Remoting;  namespace RemotingFirst  {       public class Listener      {          public static void Main()          {              RemotingConfiguration.Configure("Listener.exe.config");              Console.WriteLine("Listening for requests. Press Enter to exit");              Console.ReadLine();          }      }  }  using System;  using System.Runtime.Remoting;  namespace Client  {      public class Client      {          public static void Main()          {              RemotingConfiguration.Configure("Client.exe.config");              Remotable.RemotableType remoteObject = new Remotable.RemotableType();              Console.WriteLine(remoteObject.StringMethod());          }      }  }  //Listener.exe.config                                                                                                          事实上只要用到Socket联接,基本上就得使用Thread,是交叉使用的。  C#封装的Socket用法基本上不算很复杂,在C#里面能找到的最底层的操作也就是socket了,概念不做解释。  程序模型如下:  WinForm程序 : 启动端口侦听;监视Socket联接情况;定期关闭不活动的联接;  Listener:处理Socket的Accept函数,侦听新链接,建立新Thread来处理这些联接。  Connection:处理具体的每一个联接的会话。 1:WinForm如何启动一个新的线程来启动Listener:        //start the server          private void btn_startServer_Click(object sender, EventArgs e)          {              //this.btn_startServer.Enabled = false;              Thread _createServer = new Thread(new ThreadStart(WaitForConnect));              _createServer.Start();          }          //wait all connections          private void WaitForConnect()          {              SocketListener listener = new SocketListener(Convert.ToInt32(this.txt_port.Text));              listener.StartListening();          }  因为侦听联接是一个循环等待的函数,所以不可能在WinForm的线程里面直接执行,不然Winform也就是无法继续任何操作了,所以才指定一个新的线程来执行这个函数,启动侦听循环。  这一个新的线程是比较简单的,基本上没有启动的参数,直接指定处理函数就可以了。  2:Listener如何启动循环侦听,并且启动新的带有参数的线程来处理Socket联接会话。  先看如何建立侦听:(StartListening函数)  IPEndPoint localEndPoint = new IPEndPoint(_ipAddress, _port);          // Create a TCP/IP socket.  Socket listener = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);          // Bind the socket to the local endpoint and  listen for incoming connections.              try              {                  listener.Bind(localEndPoint);                  listener.Listen(20);//20 trucks                  // Start listening for connections.                  while (true)                  {                    // here will be suspended while waiting for a new connection.                       Socket connection = listener.Accept();                      Logger.Log("Connect", connection.RemoteEndPoint.ToString());//log it, new connection                  ……            }          }……  基本步骤比较简单:  建立本机的IPEndPoint对象,表示以本机为服务器,在指定端口侦听;  然后绑定到一个侦听Socket上;  进入while循环,等待新的联接;  如果有新的联接,那么建立新的socket来对应这个联接的会话。  值得注意的就是这一句联接代码:listener.Accept()。执行这一句的时候,程序就在这个地方等待,直到有新的联检请求的时候程序才会执行下一句。这是同步执行,当然也可以异步执行。  新的联接Socket建立了(Accept之后),对于这些新的socket该怎么办呢?他们依然是一个循环等待,所以依然需要建立新的Thread给这些Socket去处理会话(接收/发送消息),而这个Thread就要接收参数了。  Thread本身是不能接收参数的,为了让它可以接收参数,可以采用定义新类,添加参数作为属性的方法来解决。  因为每一个Socket是一个Connection周期,所以我定义了这么一个类public class Connection。这个类至少有这样一个构造函数public Connection(Socket socket); 之所以这么做,就是为了把Socket参数传给这个Connection对象,然后好让Listener启动这个Thread的时候,Thread可以知道他正在处理哪一个Socket。  具体处理的方法:(在Listener的StartListening函数,ocket connection = listener.Accept();之后) Connection gpsCn = new Connection(connection);        //each socket will be wait for data. keep the connection.  Thread thread = new Thread(new ThreadStart(gpsCn.WaitForSendData));  thread.Name = connection.RemoteEndPoint.ToString();  thread.Start();  如此一来,这个新的socket在Accept之后就在新的Thread中运行了。  3:Connection的会话处理    建立了新的Connection(也就是socket),远程就可以和这个socket进行会话了,无非就是send和receive。    现在先看看怎么写的这个线程运行的Connection. WaitForSendData函数      while (true)              {                  bytes = new byte[1024];                  string data = "";                  //systm will be waiting the msg of receive envet. like Accept();                  //here will be suspended while waiting for socket income msg.                   int bytesRec = this._connection.Receive(bytes);                  _lastConnectTime = DateTime.Now;                  if (bytesRec == 0)//close envent                  {                      Logger.Log("Close Connection", _connection.RemoteEndPoint.ToString());                      break;                  }                  data += Encoding.ASCII.GetString(bytes, 0, bytesRec);                  //…….handle your data.              }  可以看到这个处理的基本步骤如下:    执行Receive函数,接收远程socket发送的信息;    把信息从字节转换到string;    处理该信息,然后进入下一个循环,继续等待socket发送新的信息。  值得注意的有几个:    1:Receive函数。这个函数和Listener的Accept函数类似。在这个地方等待执行,如果没有新的消息,这个函数就不会执行下一句,一直等待。    2:接收的是字节流,需要转化成字符串    3:判断远程关闭联接的方式    4:如果对方的消息非常大,还得循环接收这个data。  4:如何管理这些联接(thread)  通过上边的程序,基本上可以建立一个侦听,并且处理联接会话。但是如何管理这些thread呢?不然大量产生thread可是一个灾难。  管理的方法比较简单,在Listener里面我定义了一个静态的哈希表(static public Hashtable Connections=new Hashtable();),存储Connection实例和它对应的Thread实例。而connection中也加入了一个最后联接时间的定义(private DateTime _lastConnectTime;)。在新链接建立的时候(Listener的Accept()之后)就把Connection实例和Thread实例存到哈希表中;在Connection的Receive的时候修改最后联接时间。这样我们就可以知道该Connection在哪里,并且会话是否活跃。  然后在Winform程序里头可以管理这些会话了,设置设置超时。 在网络环境下,我们最感兴趣的两个命名空间是System.Net和 System.Net.Sockets。System.Net命名空间通常与较高程的操作有关,例如download或upload,试用HTTP和其他协议进行Web请求等等,而System.Net.Sockets命名空间所包含的类通常与较低程的操作有关。如果要直接使用Sockets或者 TCP/IP之类的协议,这个命名空间的类是非常有用的。    在.Net中,System.Net.Sockets 命名空间为需要严密控制网络访问的开发人员提供了 Windows Sockets (Winsock) 接口的托管实现。System.Net 命名空间中的所有其他网络访问类都建立在该套接字Socket实现之上,如TCPClient、TCPListener 和 UDPClient 类封装有关创建到 Internet 的 TCP 和 UDP 连接的详细信息;NetworkStream类则提供用于网络访问的基础数据流等,常见的许多Internet服务都可以见到Socket的踪影,如 Telnet、Http、Email、Echo等,这些服务尽管通讯协议Protocol的定义不同,但是其基础的传输都是采用的Socket。    其实,Socket可以象流Stream一样被视为一个数据通道,这个通道架设在应用程序端(客户端)和远程服务器端之间,而后,数据的读取(接收)和写入(发送)均针对这个通道来进行。    可见,在应用程序端或者服务器端创建了Socket对象之后,就可以使用Send/SentTo方法将数据发送到连接的Socket,或者使用Receive/ReceiveFrom方法接收来自连接Socket的数据。    针对Socket编程,.NET 框架的 Socket 类是 Winsock32 API 提供的套接字服务的托管代码版本。其中为实现网络编程提供了大量的方法,大多数情况下,Socket 类方法只是将数据封送到它们的本机 Win32 副本中并处理任何必要的安全检查。如果你熟悉Winsock API函数,那么用Socket类编写网络程序会非常容易,当然,如果你不曾接触过,也不会太困难,跟随下面的解说,你会发觉使用Socket类开发 windows 网络应用程序原来有规可寻,它们在大多数情况下遵循大致相同的步骤。    在使用之前,你需要首先创建Socket对象的实例,这可以通过Socket类的构造方法来实现:  public Socket(AddressFamily addressFamily,SocketType socketType,ProtocolType protocolType);    其中,addressFamily 参数指定 Socket 使用的寻址方案,socketType 参数指定 Socket 的类型,protocolType 参数指定 Socket 使用的协议。    下面的示例语句创建一个 Socket,它可用于在基于 TCP/IP 的网络(如 Internet)上通讯。  Socket temp = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);    若要使用 UDP 而不是 TCP,需要更改协议类型,如下面的示例所示:  Socket temp = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp);    一旦创建 Socket,在客户端,你将可以通过Connect方法连接到指定的服务器,并通过Send/SendTo方法向远程服务器发送数据,而后可以通过 Receive/ReceiveFrom从服务端接收数据;而在服务器端,你需要使用Bind方法绑定所指定的接口使Socket与一个本地终结点相联,并通过Listen方法侦听该接口上的请求,当侦听到用户端的连接时,调用Accept完成连接的操作,创建新的Socket以处理传入的连接请求。使用完 Socket 后,记住使用 Shutdown 方法禁用 Socket,并使用 Close 方法关闭 Socket。    可以看出,以上许多方法包含EndPoint类型的参数,在Internet中,TCP/IP 使用一个网络地址和一个服务端口号来唯一标识设备。网络地址标识网络上的特定设备;端口号标识要连接到的该设备上的特定服务。网络地址和服务端口的组合称为终结点,在 .NET 框架中正是由 EndPoint 类表示这个终结点,它提供表示网络资源或服务的抽象,用以标志网络地址等信息。.Net同时也为每个受支持的地址族定义了 EndPoint 的子代;对于 IP 地址族,该类为 IPEndPoint。IPEndPoint 类包含应用程序连接到主机上的服务所需的主机和端口信息,通过组合服务的主机IP地址和端口号,IPEndPoint 类形成到服务的连接点。    用到IPEndPoint类的时候就不可避免地涉及到计算机IP地址,System.Net命名空间中有两种类可以得到IP地址实例:    IPAddress类:IPAddress 类包含计算机在 IP 网络上的地址。其Parse方法可将 IP 地址字符串转换为 IPAddress 实例。下面的语句创建一个 IPAddress 实例:  IPAddress myIP = IPAddress.Parse("192.168.0.1");    Dns 类:向使用 TCP/IP Internet 服务的应用程序提供域名服务。其Resolve 方法查询 DNS 服务器以将用户友好的域名(如"host.mydomain.com")映射到数字形式的 Internet 地址(如 192.168.0.1)。Resolve方法 返回一个 IPHostEnty 实例,该实例包含所请求名称的地址和别名的列表。大多数情况下,可以使用 AddressList 数组中返回的第一个地址。下面的代码获取一个 IPAddress 实例,该实例包含服务器 host.mydomain.com 的 IP 地址。  IPHostEntry ipHostInfo = Dns.Resolve("host.mydomain.com ");  IPAddress ipAddress = ipHostInfo.AddressList[0];    你也可以使用GetHostName方法得到IPHostEntry实例:  IPHosntEntry hostInfo=Dns.GetHostByName("host.mydomain.com ")    在使用以上方法时,你将可能需要处理以下几种异常:    SocketException异常:访问Socket时操作系统发生错误引发    ArgumentNullException异常:参数为空引用引发    ObjectDisposedException异常:Socket已经关闭引发    在掌握上面得知识后,下面的代码将该服务器主机( host.mydomain.com的 IP 地址与端口号组合,以便为连接创建远程终结点:  IPEndPoint ipe = new IPEndPoint(ipAddress,11000);    确定了远程设备的地址并选择了用于连接的端口后,应用程序可以尝试建立与远程设备的连接。下面的示例使用现有的 IPEndPoint 实例与远程设备连接,并捕获可能引发的异常:  try  {  temp.Connect(ipe);//尝试连接  }  //处理参数为空引用异常  catch(ArgumentNullException ae)   {  Console.WriteLine("ArgumentNullException : {0}", ae.ToString());  }  //处理操作系统异常  catch(SocketException se)  {  Console.WriteLine("SocketException : {0}", se.ToString());  }    需要知道的是:Socket 类支持两种基本模式:同步和异步。其区别在于:在同步模式中,对执行网络操作的函数(如 Send 和 Receive)的调用一直等到操作完成后才将控制返回给调用程序。在异步模式中,这些调用立即返回。  综合运用以上阐述的使用Visual C#进行Socket网络程序开发的知识,下面的程序是一个简单的Socket通讯实例,client向server发送一段测试字符串,server接收并显示出来,给予client成功相应。  //client端  using System;  using System.Text;  using System.IO;  using System.Net;  using System.Net.Sockets;  namespace socketsample  {   class Class1   {    static void Main()    {     try     {      int port = 2000;      string host = "127.0.0.1";      IPAddress ip = IPAddress.Parse(host);      IPEndPoint ipe = new IPEndPoint(ip, port);      Socket c = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);      c.Connect(ipe);      string sendStr = "hello!This is a socket test";      byte[] bs = Encoding.ASCII.GetBytes(sendStr);      c.Send(bs, bs.Length, 0);      string recvStr = "";      byte[] recvBytes = new byte[1024];      int bytes;      bytes = c.Receive(recvBytes, recvBytes.Length, 0);      recvStr += Encoding.ASCII.GetString(recvBytes, 0, bytes);      Console.WriteLine(recvStr);      c.Close();     }     catch (ArgumentNullException e)     {      Console.WriteLine("ArgumentNullException: {0}", e);     }     catch (SocketException e)     {      Console.WriteLine("SocketException: {0}", e);     }     Console.ReadLine();    }   }  }  //server端  using System;  using System.Text;  using System.IO;  using System.Net;  using System.Net.Sockets;  namespace Project1  {   class Class2   {    static void Main()    {     try     {      int port = 2000;      string host = "127.0.0.1";      IPAddress ip = IPAddress.Parse(host);      IPEndPoint ipe = new IPEndPoint(ip, port);      Socket s = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);      s.Bind(ipe);      s.Listen(0);      Socket temp = s.Accept();      string recvStr = "";      byte[] recvBytes = new byte[1024];      int bytes;      bytes = temp.Receive(recvBytes, recvBytes.Length, 0);      recvStr += Encoding.ASCII.GetString(recvBytes, 0, bytes);      Console.WriteLine(recvStr);      string sendStr = "Ok!Sucess!";      byte[] bs = Encoding.ASCII.GetBytes(sendStr);      temp.Send(bs, bs.Length, 0);      temp.Shutdown(SocketShutdown.Both);      temp.Close();      s.Shutdown(SocketShutdown.Both);      s.Close();     }     catch (ArgumentNullException e)     {      Console.WriteLine("ArgumentNullException: {0}", e);     }     catch (SocketException e)     {      Console.WriteLine("SocketException: {0}", e);     }     Console.ReadLine();    }   }  }    以上程序在VS Express 2005 .Net2.0环境下测试通过。 C#UDP的多路广播组的发送和接收  下列范例使用 UdpClient,在通讯端口11000传送UDP 资料包至多点传送位址群组 224.268.100.2。它传送命令列上指定的信息字串。   C# code   using System;   using System.Net;   using System.Net.Sockets;   using System.Text;   public class UDPMulticastSender {   private static IPAddress GroupAddress =   IPAddress.Parse("224.168.100.2");   private static int GroupPort = 11000;   private static void Send( String message) {   UdpClient sender = new UdpClient();   IPEndPoint groupEP = new IPEndPoint(GroupAddress,GroupPort);   try {   Console.WriteLine("Sending datagram : {0}", message);   byte[] bytes = Encoding.ASCII.GetBytes(message);   sender.Send(bytes, bytes.Length, groupEP);   sender.Close();   } catch (Exception e) {   Console.WriteLine(e.ToString());   }   }   public static int Main(String[] args) {   Send(args[0]);   return 0;   }   }   下列范例使用 UdpClient,在通讯端口  11000  监听广播到多点传送位址群组 224.168.100.2 的 UDP  资料包。它接收信息字串,并將信息写入主控台 (Console)。   C# code using System;   using System.Net;   using System.Net.Sockets;   using System.Text;   public class UDPMulticastListener {   private static readonly IPAddress GroupAddress =   IPAddress.Parse("224.168.100.2");   private const int GroupPort = 11000;   private static void StartListener() {   bool done = false;   UdpClient listener = new UdpClient();   IPEndPoint groupEP = new IPEndPoint(GroupAddress,GroupPort);   try {   listener.JoinMulticastGroup(GroupAddress);   listener.Connect(groupEP);   while (!done) {   Console.WriteLine("Waiting for broadcast");   byte[] bytes = listener.Receive( ref groupEP);   Console.WriteLine("Received broadcast from {0} :\n {1}\n",   groupEP.ToString(),   Encoding.ASCII.GetString(bytes,0,bytes.Length));   }   listener.Close();   } catch (Exception e) {   Console.WriteLine(e.ToString());   }   }   public static int Main(String[] args) {   StartListener();   return 0;   }   } using System;   using System.Net;   using System.Net.Sockets;   using System.Text;   public class UDPMulticastSender {   private static IPAddress GroupAddress =   IPAddress.Parse("224.168.100.2");   private static int GroupPort = 11000;   private static void Send( String message) {   UdpClient sender = new UdpClient();   IPEndPoint groupEP = new IPEndPoint(GroupAddress,GroupPort);   try {   Console.WriteLine("Sending datagram : {0}", message);   byte[] bytes = Encoding.ASCII.GetBytes(message);   sender.Send(bytes, bytes.Length, groupEP);   sender.Close();   } catch (Exception e) {   Console.WriteLine(e.ToString());   }   }   public static int Main(String[] args) {   Send(args[0]);   return 0;   }   } C# code try                 {                     UdpClient udp=new UdpClient(new IPEndPoint(ipAddress,startPort+i));                     udp.Close();                                         unUsedPort=startPort+i;                     break;                 }                 catch                 {                 } using System; using System.Collections.Generic; using System.ComponentModel; using System.Data; using System.Drawing; using System.Text; using System.Windows.Forms; using System.Collections; using System.Collections.Specialized; using System.Threading; using System.Net.Sockets; using System.Net; using System.Runtime.Serialization; using System.Runtime.Serialization.Formatters.Binary; using System.IO; namespace 聊天工具服务器 {     public partial class FormMain : Form     {         public FormMain()         {             InitializeComponent();         }         #region 字段定义         ///         /// 服务器程序使用的端口,默认为8888         ///         private int _port = 8888;         ///         /// 接收数据缓冲区大小2K         ///         private const int _maxPacket =2 * 1024;         ///         /// 服务器端的监听器         ///         private TcpListener _tcpl = null;         Thread _receiveThread;         ///         /// 保存所有客户端会话的哈希表         ///         private Hashtable _transmit_tb = new Hashtable();         ///         /// 当前文件路径         ///         string MyPath = null;         ///         /// 用户基本信息表,包括UserName,UserPwd,UserNich,UserImg,ZX,UserIp         ///         DataTable TabUser = new DataTable();         ///         /// 用户消息表,保存用户不在线时的消息         ///         DataTable TabUserMessage = new DataTable();         #endregion         ///         /// 序列化在线列表,向客户端返回序列化后的字节数组         ///         /// 序列化后的字节数组         private byte[] SerializeOnlineList()         {             StringCollection onlineList = new StringCollection();             foreach (object o in _transmit_tb.Keys)             {                 onlineList.Add(o as string);             }             IFormatter format = new BinaryFormatter();             MemoryStream stream = new MemoryStream();             format.Serialize(stream, onlineList);             byte[] ret = stream.ToArray();             stream.Close();             return ret;         }         ///         /// 序列化好友列表,向客户端返回序列化后的datatable         ///         /// 序列化后的字节数组         private bool SerializeFriendList(object obj, Socket clientSkt)         {             DataTable TabmyFriend = new DataTable();             TabmyFriend.TableName = obj as string;             try {                 TabmyFriend.ReadXml(MyPath + "\\UserFriend\\" + TabmyFriend.TableName + ".xml");                 TabmyFriend.Columns.Add("UserImg", typeof(String));                 TabmyFriend.Columns.Add("UserNich", typeof(String));                 TabmyFriend.Columns.Add("ZX", typeof(Boolean));                 TabmyFriend.Columns.Add("UserIp", typeof(String));                 foreach (DataRow myrow in TabmyFriend.Rows)                 {                     DataRow[] DataRows = TabUser.Select(" UserName = '" + myrow["UserName"].ToString() + "'");                     if (DataRows.Length > 0)                     {                         myrow["UserImg"] = DataRows[0]["UserImg"].ToString();                         myrow["UserNich"] = DataRows[0]["UserNich"].ToString();                       try                       {                             myrow["ZX"] = (bool)DataRows[0]["ZX"];                             myrow["UserIp"] = DataRows[0]["UserIp"].ToString();                       }                          catch                         {                             myrow["ZX"] = false;                             myrow["UserIp"] = "";                         }                     }                 }             }             catch             {                 TabmyFriend.Columns.Add("UserName", typeof(String));                 TabmyFriend.Columns.Add("UserImg", typeof(String));                 TabmyFriend.Columns.Add("ZX", typeof(Boolean));                 TabmyFriend.Columns.Add("UserIp", typeof(String));             }             IFormatter format = new BinaryFormatter();             MemoryStream stream = new MemoryStream();             format.Serialize(stream, TabmyFriend);             stream.Position = 0;             byte[] ret = new byte[_maxPacket];             int count = 0;             count = stream.Read(ret, 0, _maxPacket);             //先发送响应信号,用户客户机的判断             clientSkt.Send(Encoding.Unicode.GetBytes("cmd::RequestFriendList"));             while (count >0)             {                 clientSkt.Send(ret);                 count =  stream.Read(ret, 0, _maxPacket);               }             //发送结束信号               clientSkt.Send(Encoding.Unicode.GetBytes("Find::RequestFriendListEnd"));                 stream.Close();             return true ;         }         private void FormMain_Load(object sender, EventArgs e)         {             MyPath = Application.StartupPath;             Read_User();             ReadTabUserMessage();             _receiveThread = new Thread(new ThreadStart(StartUp));             _receiveThread.Start();         }         ///         /// 读取所有用户信息         ///         private void Read_User()         {             try             {                 TabUser.ReadXml(MyPath + "\\User.xml");             }             catch             {                 TabUser.TableName = "User";                 TabUser.Columns.Add("UserName", typeof(String));                 TabUser.Columns.Add("UserPwd", typeof(String));                 TabUser.Columns.Add("UserNich", typeof(String));                 TabUser.Columns.Add("UserImg", typeof(String));             }             TabUser.Columns.Add("ZX", typeof(Boolean));             TabUser.Columns.Add("UserIp", typeof(String));         }         ///         /// 新用户上/下线后,更新其好友的(好友列表)         ///         ///         ///         ///         private void UpdateFriendList(string UserName, bool OnLine, string IpAddress)         {             DataTable TabmyFriend = new DataTable();             TabmyFriend.TableName = UserName;             string svrlog = null;             string []UserInformation = new string[2];//UserName + "$" + IpAddress;             UserInformation[0] = UserName;             UserInformation[1] = IpAddress;             IFormatter format = new BinaryFormatter();             MemoryStream stream = new MemoryStream();             format.Serialize(stream, UserInformation);             byte[] ret = stream.ToArray();             stream.Close();             if (OnLine)             {                 svrlog = "cmd::RequestAddFriendList";             }             else             {                 svrlog = "cmd::RequestRemoveFriendList";                 DataRow[] DataRows = TabUser.Select(" UserName = '" + UserName + "'");                 if (DataRows.Length > 0)                 {                     DataRows[0]["ZX"] = false;                     DataRows[0]["UserIp"] = "";                 }             }             try             {                 TabmyFriend.ReadXml(MyPath + "\\UserFriend\\" + TabmyFriend.TableName + ".xml");                 foreach (DataRow myrow in TabmyFriend.Rows)                 {                     if(_transmit_tb.ContainsKey(myrow["UserName"].ToString()))                     {                         Socket _clientSkt = _transmit_tb[myrow["UserName"].ToString()] as Socket;                       _clientSkt.Send(Encoding.Unicode.GetBytes(svrlog));                       _clientSkt.Send(ret);                     }                 }             }             catch             { }         } [code=C#][/code ///         /// 线程执行体,转发消息         ///         /// 传递给线程执行体的用户名,用以与用户通信         private void ThreadFunc(object obj)         {             //通过转发表得到当前用户套接字             Socket clientSkt = _transmit_tb[obj] as Socket;           //主循环             while (true)             {                 try                 {                     //接受第一个数据包。                     //由于程序逻辑结构简单,所以在这里对客户机发送的第一个包内容作逐一判断,                     //这里的实现不够优雅,但不失为此简单模型的一个解决之道。                     byte[] packetBuff = new byte[_maxPacket];                     clientSkt.Receive(packetBuff);                     string _str = Encoding.Unicode.GetString(packetBuff).TrimEnd('\0');                     //如果是发给不在线好友的信息                     if (_str.StartsWith("cmd::FriendMessage"))                     {                         string UserName = _str.Substring("cmd::FriendMessage".Length, 20).Trim();                         string MessageS = _str.Substring("cmd::FriendMessage".Length + 20, _str.Length - "cmd::FriendMessage".Length - 20);                         SaveMessage(obj as string, UserName, MessageS);                         continue;                     }                     //如果是离线请求                     if (_str.StartsWith("cmd::RequestLogout"))                     {                         _transmit_tb.Remove(obj);                         UpdateFriendList((string)obj, false, "");                       //  string svrlog = string.Format("[系统消息]用户 {0} 在 {1} 已断开... 当前在线人数: {2}\r\n\r\n", obj, DateTime.Now, _transmit_tb.Count);                       //  Console.WriteLine(svrlog);                         //向所有客户机发送系统消息                         //foreach (DictionaryEntry de in _transmit_tb)                         //{                         //    string _clientName = de.Key as string;                         //    Socket _clientSkt = de.Value as Socket;                         //    _clientSkt.Send(Encoding.Unicode.GetBytes(svrlog));                         //}                         Thread.CurrentThread.Abort();                     }                     //如果是请求好友列表                     if (_str.StartsWith("cmd::RequestFriendList"))                     {                         SerializeFriendList(obj, clientSkt);                                              // 将该用户不在线时的信息发送给用户                         DataTable TabMessage = ReadMessage(obj as string);                         if (TabMessage != null)                         {                             foreach (DataRow myrow in TabMessage.Rows)                             {                                 if (myrow["SendUserName"].ToString() == "System::Message")                                 {                                     clientSkt.Send(Encoding.Unicode.GetBytes(myrow["Message"].ToString()));                                 }                                 else                                 {                                     clientSkt.Send(Encoding.Unicode.GetBytes("cmd::FriendMessage" + myrow["SendUserName"].ToString().PadRight(20, ' ') + myrow["Message"].ToString()));                                 }                             }                         }                         //这里不需要再继续接受后继数据包了,跳出当前循环体。                         continue;                     }                     ////如果是请求好友列表                     //if (_str.StartsWith("cmd::RequestOnLineList"))                     //{                     //    byte[] onlineBuff = SerializeOnlineList();                     //    //先发送响应信号,用户客户机的判断                     //    clientSkt.Send(Encoding.Unicode.GetBytes("cmd::RequestOnLineList"));                     //    clientSkt.Send(onlineBuff);                     //    //这里不需要再继续接受后继数据包了,跳出当前循环体。                     //    continue;                     //}                     //查找用户                     if (_str.StartsWith("Find::FindFriend"))                     {                         DataTable TabFind = TabUser.Clone();                         DataRow [] FindRow =null  ;                         string UserName = _str.Substring("Find::FindFriend".Length, _str.Length - "Find::FindFriend".Length);                         if (UserName.Equals("Find::WhoOnLine"))                         { //看谁在线                             FindRow = TabUser.Select(" ZX = 1");                         }                         else//精确查找                         {                             FindRow = TabUser.Select("UserName = '" + UserName + "'");                         }                         foreach (DataRow myrow in FindRow)                         {                             TabFind.ImportRow(myrow);                         }                         clientSkt.Send(Encoding.Unicode.GetBytes("Find::FindFriend"));                         IFormatter format = new BinaryFormatter();                         MemoryStream stream = new MemoryStream();                         format.Serialize(stream, TabFind);                         stream.Position = 0;                         byte[] ret = new byte[_maxPacket];                         int count = 0;                         count = stream.Read(ret, 0, _maxPacket);                         while (count >0)                         {                             clientSkt.Send(ret);                           count =  stream.Read(ret, 0, _maxPacket);                         }                         clientSkt.Send(Encoding.Unicode.GetBytes("Find::FindFriendEnd"));                           stream.Close();                         TabFind = null;                         FindRow = null; //这里不需要再继续接受后继数据包了,跳出当前循环体。                         continue;                     }                     //请求添加好友                     if (_str.StartsWith("Find::AddFriendAsk"))                     {                         string UserName = _str.Substring("Find::AddFriendAsk".Length, _str.Length - "Find::AddFriendAsk".Length);                         //通过转发表查找接收方的套接字                         if (_transmit_tb.Count != 0 && _transmit_tb.ContainsKey(UserName))                         {                             Socket receiverSkt = _transmit_tb[UserName] as Socket;                             receiverSkt.Send(Encoding.Unicode.GetBytes("Find::AddFriendAsk" + obj as string));                         }                         //这里不需要再继续接受后继数据包了,跳出当前循环体。                         continue;                     }                     //回复答应添加好友                     if (_str.StartsWith("Find::AddFriendYes"))                     {                         string UserName = _str.Substring("Find::AddFriendYes".Length, _str.Length - "Find::AddFriendYes".Length);                       //// 保存数据                         DataTable TabmyFriend = new DataTable() ;                         //保存该用户                         TabmyFriend.ReadXml(MyPath + "\\UserFriend\\" +  obj as string + ".xml");                         DataRow newRow = TabmyFriend.NewRow();                         newRow["UserName"] = UserName;                         TabmyFriend.Rows.Add(newRow);                         TabmyFriend.WriteXml(MyPath + "\\UserFriend\\" + obj as string + ".xml", XmlWriteMode.WriteSchema, false);                         //保存其好友                         TabmyFriend = new DataTable();                         TabmyFriend.ReadXml(MyPath + "\\UserFriend\\" + UserName + ".xml");                         DataRow newRow1 = TabmyFriend.NewRow();                         newRow1["UserName"] = obj as string;                         TabmyFriend.Rows.Add(newRow1);                         TabmyFriend.WriteXml(MyPath + "\\UserFriend\\" + UserName + ".xml", XmlWriteMode.WriteSchema, false);                         TabmyFriend = null;               //更新好友列表                         SerializeFriendList(obj, clientSkt); 上面发了服务器端,没发客户端,现在补上!不知道写的好不好,见笑了 C# code public partial class Form1 : Form     {         private TcpClient client;         private bool isExit = false;         private NetworkStream networkStream;         private EventWaitHandle allDone = new EventWaitHandle(false, EventResetMode.ManualReset);         #region 用于一个线程操作另一个线程的控件         private delegate void SetListBoxCallback(string str);         private SetListBoxCallback setListBoxCallBack;         private delegate void SetRichTextBoxCallback(string str);         private SetRichTextBoxCallback setRichTextBoxCallBack;         #endregion         public Form1()         {             InitializeComponent();             listBoxStatus.HorizontalScrollbar = true;             setListBoxCallBack = new SetListBoxCallback(SetListBox);             setRichTextBoxCallBack = new SetRichTextBoxCallback(SetReceiveText);         }         //状态显示         private void SetListBox(string str)         {             listBoxStatus.Items.Add(str);             listBoxStatus.SelectedIndex = listBoxStatus.Items.Count - 1;             listBoxStatus.ClearSelected();         }         //接收客户端信息         private void SetReceiveText(string str)         {             richTextBoxReceive.AppendText(str);         }         //连接服务器....         private void buttonConnet_Click(object sender, EventArgs e)         {             client = new TcpClient(AddressFamily.InterNetwork);             //得到服务器IP             IPAddress ip= IPAddress.Parse("127.0.0.1");             //创建一个委托,并知名在异步操作完成时执行的方法             AsyncCallback callback = new AsyncCallback(RequestCallBack);             allDone.Reset();             client.BeginConnect(ip, 7100, RequestCallBack, client);         }         private void RequestCallBack(IAsyncResult ar)         {             allDone.Set();             try             {                 client = (TcpClient)ar.AsyncState;                 client.EndConnect(ar);                 listBoxStatus.Invoke(setListBoxCallBack, string.Format("与服务器{0}连接成功", client.Client.RemoteEndPoint));                 networkStream = client.GetStream();                 ReadObject readObject = new ReadObject(networkStream, client.ReceiveBufferSize);                 networkStream.BeginRead(readObject.bytes, 0, readObject.bytes.Length, ReadCallBack, readObject);             }             catch (Exception e1)             {                 listBoxStatus.Invoke(setListBoxCallBack, e1.Message);                 return;             }         }         //异步操作完成时执行的回调调用的方法         private void ReadCallBack(IAsyncResult ar)         {             try             {                 ReadObject ro = (ReadObject)ar.AsyncState;                 int count = ro.netStream.EndRead(ar);                 richTextBoxReceive.Invoke(setRichTextBoxCallBack, System.Text.Encoding.UTF8.GetString(ro.bytes, 0, count));                 if (isExit == false)                 {                     ro = new ReadObject(networkStream, client.ReceiveBufferSize);                     networkStream.BeginRead(ro.bytes, 0, ro.bytes.Length, ReadCallBack, ro);                 }             }             catch (Exception e2)             {                 listBoxStatus.Invoke(setListBoxCallBack, e2.Message);                 return;             }         }         //发送数据         private void SendString(string str)         {             try             {                 byte[] by = System.Text.Encoding.UTF8.GetBytes(str+"\r\n");                 networkStream.BeginWrite(by, 0, by.Length, new AsyncCallback(SendCallBack), networkStream);                 networkStream.Flush();             }catch(Exception e3){                 listBoxStatus.Invoke(setListBoxCallBack, e3.Message);                 return;             }         }         //发送数据回调的方法         private void SendCallBack(IAsyncResult ar)         {             try             {                 networkStream.EndWrite(ar);             }             catch (Exception e4)             {                 listBoxStatus.Invoke(setListBoxCallBack, e4.Message);                 return;             }         }         private void buttonSend_Click(object sender, EventArgs e)         {             SendString(richTextBoxSend.Text);             richTextBoxSend.Clear();         }         private void Form1_FormClosing(object sender, FormClosingEventArgs e)         {             isExit = true;             allDone.Set();         }     }

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