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
(编辑:李大同)
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