使用websocket-sharp来创建c#版本的websocket服务

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websocket-sharp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> ("/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> ("/Echo");
wssv.AddWebSocketService<Chat> ("/Chat");
wssv.AddWebSocketService<Chat> ("/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<ScannerHandler>("/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

<button onclick="scan()">扫描</button>
  • initWS创建连接,支持断线重连
  • 可以调用scan函数,发送scan指令
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