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