System.IO系列：局域网内多线程使用命名管道在进程之间通信实例

本文介绍命名管道使用实例，文中例子是几个客户端都通过一台服务器获得新生成的int类型id。

服务器端功能：当客户端请求一个新的id时，将现有id自增1，然后返回给客户端。

服务器端实现：在程序启动时，启动n个线程，在每个线程中都声明一个NamedPipeServerStream的实例，并循环的 WaitForConnection()，将新的id写入到命名管道中，然后断开连接。在程序退出时释放NamedPipeServerStream实例

如下代码实现： 

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using System; using System.Collections.Generic; using System.Linq; using System.Text;     using System.IO; using System.IO.Pipes; using System.Threading;   namespace IDServer {     class Program     {         /// <summary>         /// 命名管道名字         /// </summary>         private const string PIPE_NAME = "testNetworkPipe";           //定义线程数，也是NamedPipeServerStream的允许最多的实例数         private const int MAX_THREADS_COUNT = 3;         private static volatile int _runingThreadCount = 0;           private static volatile int _newId = 0;           //实例数组         private static NamedPipeServerStream[] _serverStreams;           static void Main(string[] args)         {             _serverStreams = new NamedPipeServerStream[MAX_THREADS_COUNT];               //在进程退出时释放所有NamedPipeServerStream实例             AppDomain.CurrentDomain.ProcessExit += new EventHandler(CurrentDomain_ProcessExit);                           //启动线程             StartServers();               Console.Read();         }           /// <summary>         /// 在进程退出时释放命名管道         /// </summary>         /// <param name="sender"></param>         /// <param name="e"></param>         static void CurrentDomain_ProcessExit(object sender, EventArgs e)         {             if (_serverStreams != null)             {                 foreach (NamedPipeServerStream item in _serverStreams)                 {                     item.Dispose();                 }             }         }           /// <summary>         /// 启动服务器端线程         /// </summary>         private static void StartServers()         {             for (int i = 0; i < MAX_THREADS_COUNT; i++)             {                 Thread thread = new Thread(new ThreadStart(StartNewIDServer));                 thread.Start();             }         }             /// <summary>         /// 启动一个NamedPipeServerStream实例         /// </summary>         private static void StartNewIDServer()         {             NamedPipeServerStream stream = null;             Console.WriteLine("start server in thread " + Thread.CurrentThread.ManagedThreadId);               stream = _serverStreams[_runingThreadCount] = new NamedPipeServerStream(PIPE_NAME,                  PipeDirection.InOut,                  MAX_THREADS_COUNT,                  PipeTransmissionMode.Message,                  PipeOptions.None);             int threadNo = _runingThreadCount;             _runingThreadCount += 1;               while (true)             {                 stream.WaitForConnection();                 int newId = ++_newId;                   byte[] bytes = BitConverter.GetBytes(newId);                 stream.Write(bytes, 0, bytes.Length);                 stream.Flush();                 Console.Write("threadNo:" + Thread.CurrentThread.ManagedThreadId + "\r");                 stream.Disconnect();             }         }       } }

客户端的功能是不断的发出获得新id的请求，并打印新id，在客户端可以配置服务端的服务器IP。

如下代码：

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using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Threading;   namespace IDClient {     class Program     {         private const string PIPE_NAME = "testNetworkPipe";           static void Main(string[] args)         {             Console.WriteLine("请输入任何字符回车开始执行程序..");             Console.Read();             do             {                 //内网服务器ip，必须是局域网                 string serverName = "127.0.0.1";                 //声明NamedPipeClientStream实例                 using (var clientStream = new System.IO.Pipes.NamedPipeClientStream(serverName, PIPE_NAME))                 {                     //连接服务器                     clientStream.Connect(1000);                     //设置为消息读取模式                     clientStream.ReadMode = System.IO.Pipes.PipeTransmissionMode.Message;                       do                     {                         byte[] bytes = new byte[4];                         clientStream.Read(bytes, 0, 4);                         int val = BitConverter.ToInt32(bytes, 0);                         Console.Write("NewID == " + val + "\r");                     } while (!clientStream.IsMessageComplete);                 }                   Thread.Sleep(1);             } while (true);         }     } }

在sql server中就使用了命名管道在局域网内挂进程通讯。

在声明NamedPipeServerStream实例是可以指定其实例个数，如果实例数超过这个数，就会抛出“所有管道范例都在使用中”的IO异常。

本例不可以在实际项目中使用。