Asp.net core中的websocket

Websocket是html5后的产物，对于asp.net core中也得到了支持，首先在NuGet中添加Microsoft.AspNetCore.WebSockets的引用（现在是1.0.1版本，2017年3月7日发布的）。
首先在Configure中添加中间件

//添加websocket中间件
app.UseWebSockets();

接下来就要定义自己处理websocket的中间件了，代码如下：

using Microsoft.AspNetCore.Http;
using System;
using System.Net.WebSockets;
using System.Threading;
using System.Threading.Tasks;

namespace Asp.NetCore_WebPage.Middleware
{
/// <summary>
/// websocket中间件，客户端发送的信息显示在控件台上，客户端会定时收到服务端推送的时间
/// </summary>
public class WebSocketNotifyMiddleware
{
/// <summary>
/// 管道代理对象
/// </summary>
private readonly RequestDelegate _next;
/// <summary>
///
/// </summary>
/// <param name="next"></param>
public WebSocketNotifyMiddleware(RequestDelegate next)
{
_next = next;
}
/// <summary>
/// 中间件调用
/// </summary>
/// <param name="context"></param>
/// <returns></returns>
public Task Invoke(HttpContext context)
{
//判断是否为websocket请求
if (context.WebSockets.IsWebSocketRequest)
{
//接收客户端
var webSocket = context.WebSockets.AcceptWebSocketAsync().Result;
//启用一个线程处理接收客户端数据
new Thread(Accept).Start(webSocket);
while (webSocket.State == WebSocketState.Open)
{
webSocket.SendAsync(new ArraySegment<byte>(System.Text.Encoding.UTF8.GetBytes($"{DateTime.Now}")), System.Net.WebSockets.WebSocketMessageType.Text, true, CancellationToken.None);
Thread.Sleep(1000);
}
}
return this._next(context);

}
/// <summary>
/// 接收客户端数据方法，这里可以根据自己的需求切换功能代码
/// </summary>
/// <param name="obj"></param>
void Accept(object obj)
{
var webSocket = obj as WebSocket;
while (true)
{
var acceptArr = new byte[1024];

var result = webSocket.ReceiveAsync(new ArraySegment<byte>(acceptArr), CancellationToken.None).Result;

var acceptStr = System.Text.Encoding.UTF8.GetString(acceptArr).Trim(char.MinValue);
Console.WriteLine("收到信息：" + acceptStr);
}

}
}
}

添加中间件扩展

using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Http;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Net.WebSockets;
using System.Threading;
using System.Threading.Tasks;

namespace Asp.NetCore_WebPage.Middleware
{
/// <summary>
/// websocket通知中间件扩展
/// </summary>
public static class WebSocketNotifyMiddlewareExtensions
{
/// <summary>
/// 使用websocket通知
/// </summary>
/// <param name="builder"></param>
/// <returns></returns>
public static IApplicationBuilder UseWebSocketNotify(
this IApplicationBuilder builder)
{
return builder.UseMiddleware<WebSocketNotifyMiddleware>();
}
}
}

这样，就可以在Startup.cs中的Configure中添加自己创建的中间件了，代码如下：

//添加websocket中间件
app.UseWebSockets();
app.UseWebSocketNotify();

到此服务端创建完成，接下来看客户端：

<div>
当前在数据：<div id="message"></div>
<div id="output"></div>
<input class="form-control" type="text" id="sendtxt" value="测试" />
<input type="button" onclick="start()" value="开始" />
<input type="button" onclick="send()" value="发送" />
</div>
@section scripts{
<script>
var socket;
var uri = "ws://localhost:5000/ws";
//初始化连接
function doConnect(open, accept, close, error) {
console.log("doConnect")
//创建websocket,并定义事件回调
socket = new WebSocket(uri);
socket.onopen = function (e) { open();};
socket.onclose = function (e) { close(); };
socket.onmessage = function (e) {
accept(e.data);
};
socket.onerror = function (e) { error(e.data); };
}
//发送信息
function doSend(message) {
console.log("doSend")
socket.send(message);
}
//关闭socket
function doClose() {
console.log("doClose")
socket.close();
}
//打开连接回调
function open() {
console.log("open")
document.getElementById("message").innerText = "连接打开";
}
//接收数据回调
function accept(result) {
console.log("accept")
document.getElementById("output").innerText=result;
}
//关闭连接回调
function close() {
console.log("close")
document.getElementById("message").innerText="连接关闭";
}//错误回调
function error(result) {
console.log("error")
alert("错误："+result);
}
//开始方法
function start() {
console.log("start")
doConnect(open, accept, close, error);
}
function send()
{
console.log("send")
doSend(document.getElementById("sendtxt").value);
}
</script>
}

这里只是一个基本的例子，可以根据自己的业务来实现不同的功能。