当前有一个需求，需要网页端调用扫描仪，javascript不具备调用能力，因此需要在机器上提供一个ws服务给前端网页调用扫描仪。而扫描仪有一个c#版本的API，因此需要寻找一个c#的websocket库。

java里有大名鼎鼎的netty，通过搜索，c#可以选择来实现websocket Server。

使用websocket-sharp创建websocket server

using System;using WebSocketSharp;using WebSocketSharp.Server;namespace Example{  public class Laputa : WebSocketBehavior  {    protected override void OnMessage (MessageEventArgs e)    {      var msg = e.Data == "BALUS"                ? "I've been balused already..."                : "I'm not available now.";      Send (msg);    }  }  public class Program  {    public static void Main (string[] args)    {      var wssv = new WebSocketServer ("ws://dragonsnest.far");      wssv.AddWebSocketService
      
        ("/Laputa");      wssv.Start ();      Console.ReadKey (true);      wssv.Stop ();    }  }}
      

 

Step 1

Required namespace.

using WebSocketSharp.Server;

The WebSocketBehavior and WebSocketServer 两个类需要引用 WebSocketSharp.Server namespace.

Step 2

编写处理类，需要继承 WebSocketBehavior class.

例如，如果你要创建一个echo Service,

using System;using WebSocketSharp;using WebSocketSharp.Server;public class Echo : WebSocketBehavior{  protected override void OnMessage (MessageEventArgs e)  {    Send (e.Data);  }}

 

再提供一个 chat service,

using System;using WebSocketSharp;using WebSocketSharp.Server;public class Chat : WebSocketBehavior{  private string _suffix;  public Chat ()    : this (null)  {  }  public Chat (string suffix)  {    _suffix = suffix ?? String.Empty;  }  protected override void OnMessage (MessageEventArgs e)  {    Sessions.Broadcast (e.Data + _suffix);  }}

 

可以通过继承WebSocketBehavior类来自定义Service.

通过重载 WebSocketBehavior.OnMessage (MessageEventArgs) 方法, 来处理消息

同时你也可以重载 WebSocketBehavior.OnOpen (), WebSocketBehavior.OnError (ErrorEventArgs), 和 WebSocketBehavior.OnClose (CloseEventArgs) 方法,来处理websocket连接事件。

通过WebSocketBehavior.Send 方法来给客户端发送消息。

If you would like to get the sessions in the service, you should access the WebSocketBehavior.Sessions property (returns a WebSocketSharp.Server.WebSocketSessionManager).

The WebSocketBehavior.Sessions.Broadcast method can send data to every client in the service.

Step 3

创建 WebSocketServer 对象.

var wssv = new WebSocketServer (4649);wssv.AddWebSocketService
      
        ("/Echo");wssv.AddWebSocketService
       
         ("/Chat");wssv.AddWebSocketService
        
          ("/ChatWithNyan", () => new Chat (" Nyan!"));
        
       
      

Step 4

启动 WebSocket server.

wssv.Start ();

Step 5

停止 WebSocket server.

wssv.Stop (code, reason);

测试Demo

目的：对外提供一个websocket服务，让网页端的js可以调用扫描仪

服务端代码

class Program    {        static void Main(string[] args)        {            var wssv = new WebSocketServer(10086);            wssv.AddWebSocketService
      
       ("/scan");            wssv.Start();            if (wssv.IsListening)            {                Console.WriteLine("Listening on port {0}, and providing WebSocket services:", wssv.Port);                foreach (var path in wssv.WebSocketServices.Paths)                    Console.WriteLine("- {0}", path);            }            Console.WriteLine("\nPress Enter key to stop the server...");            Console.ReadLine();            wssv.Stop();        }    }    public class ScannerHandler : WebSocketBehavior    {        protected override void OnMessage(MessageEventArgs e)        {            if(e.Data == "scan")            {                ScanResult result = ScanerHelper.Scan("D:\\test.jpg");                if (result.Success)                {                    Console.WriteLine("scan success");                    Send("scan success");                }                else                {                    Send("scan eror");                }            }                   }    }
      

 

前端代码

javascript代码

var ws;    function initWS() {        ws = new WebSocket("ws://127.0.0.1:10086/scan");        ws.onopen = function () {            console.log("Openened connection to websocket");        };        ws.onclose = function () {            console.log("Close connection to websocket");            // 断线重连            initWS();        }        ws.onmessage = function (e) {            alert(e.data)        }    }        initWS();    function scan() {        ws && ws.send('scan');    }

 

html代码

扫描

• initWS创建连接，支持断线重连
• 可以调用scan函数，发送scan指令