.NetCore WebSocket简单实现

项目需要使用.net core的webapi后台处理一个大文件，同时向客户端实时返回处理进度。所以实现了一个简单demo，记录一下。

一、服务端

1. 新建了一个handler

2.SocketHandler.cs内容如下

using DotnetCoreWebAPI.Common;
using DotnetCoreWebAPI.Models;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Http;
using Newtonsoft.Json;
using System;
using System.Collections;
using System.Collections.Generic;
using System.Linq;
using System.Net.WebSockets;
using System.Text;
using System.Threading;
using System.Threading.Tasks;

namespace DotnetCoreWebAPI.Handler
{
    public class SocketHandler
    {
        public const int BufferSize = 4096;
        public string basestringjson = string.Empty;

        WebSocket socket;

        SocketHandler(WebSocket socket)
        {
            this.socket = socket;
        }

        async Task EchoLoop()
        {
            var buffer = new byte[BufferSize];
            var seg = new ArraySegment(buffer);


            while (this.socket.State == WebSocketState.Open)
            {
                var incoming = await this.socket.ReceiveAsync(seg, CancellationToken.None);
                string receivemsg = Encoding.UTF8.GetString(buffer, 0, incoming.Count);
                if (receivemsg == "get")
                {
                    string stringJson = "";

                    List infolist = new List();
                    Hashtable newtable = CommonInfo.ProgressInfo;
                    if (newtable != null)
                    {
                        try
                        {
                            foreach (DictionaryEntry i in newtable)
                            {
                                AddressMatchProgressModel pgmodel = new AddressMatchProgressModel();
                                pgmodel = (AddressMatchProgressModel)i.Value;
                                infolist.Add(pgmodel);
                            }
                        }
                        catch (Exception ex)
                        {
                            Console.WriteLine(ex.Message);
                        }
                    }
                    stringJson = JsonConvert.SerializeObject(infolist);


                    string userMsg = stringJson;
                    byte[] x = Encoding.UTF8.GetBytes(userMsg);
                    var outgoing = new ArraySegment(x);
                    await this.socket.SendAsync(outgoing, WebSocketMessageType.Text, true, CancellationToken.None);
                }
                //var incoming = await this.socket.ReceiveAsync(seg, CancellationToken.None);
                //var outgoing = new ArraySegment(buffer, 0, incoming.Count);
                //await this.socket.SendAsync(outgoing, WebSocketMessageType.Text, true, CancellationToken.None);

            }
        }

        static async Task Acceptor(HttpContext hc, Func n)
        {
            if (!hc.WebSockets.IsWebSocketRequest)
                return;

            var socket = await hc.WebSockets.AcceptWebSocketAsync();
            var h = new SocketHandler(socket);
            await h.EchoLoop();
        }

        /// 

        /// branches the request pipeline for this SocketHandler usage
        /// 
        /// 
        public static void Map(IApplicationBuilder app)
        {
            app.UseWebSockets();
            app.Use(SocketHandler.Acceptor);
        }
    }
}

(ps:这里遇到了一个小问题 ，记录一下。我在另一个地方处理大文件的，并把处理进度实时更新在一个全局变量hashtable里，然后在websocket服务端获取这个变量的值，从而得到处理进度主动推送给客户端。问题是hashtable在不断的写入同时在读取，有时候便会出现movenext异常了。所以这里将全局变量hashtable赋值给了一个新的hashtable，这样就可以保证在websocket服务端获取进度数据的时候，这个hasntable的值是不会在遍历的过程中变化的。）

3.startup.cs添加路由

 二、客户端

客户端js脚本写的

//启动websocket
                function startWebsocket() {
                    var ws = new WebSocket("ws://localhost:9957/ws");
                    ws.onopen = function (evt) {
                        console.log("Connection open ...");
                        isOpenWebSocket = true;
                        ws.send("get");
                    };
                    ws.onmessage = function (evt) {
                        isOpenWebSocket = true;
                        console.log("Received Message: " + evt.data);
                        var data = $.parseJSON(evt.data);
                        if (data.length > 0) {

                            var allfinish = true;
                            for (var num in data) {
                                var gid = data[num].Gid;
                                var fileName = data[num].UploadFileName;
                                var progress = data[num].Progress;
                                if ($("#" + gid).length <= 0) {
                                    //当前进度条不存在
                                    $("#progressbox").append("
" + fileName + "处理中
");

                                }
                                $("#" + gid).css("width", progress + "%").val("aria-valuenow", progress);

                                if (progress == "100") {
                                    $("#" + gid + "_span").html(fileName + '处理完成,下载');
                                } else {
                                    allfinish = false;
                                }
                            }

                            if (allfinish) {
                                //进度全部100%
                                ws.close();
                                isOpenWebSocket = false;
                            } else {
                                ws.send("get");
                            }

                        } else {
                            //进度数据不存在,断开连接
                            ws.close();
                            isOpenWebSocket = false;
                        }

                        //ws.send("");

                    };
                    ws.onclose = function (evt) {
                        isOpenWebSocket = false;
                        console.log("Connection closed.");
                    };
                    ws.onerror = function (evt) {
                        write("Error: " + evt.data);
                    };
                    //强制关闭浏览器  调用websocket.close（）,进行正常关闭
                    window.onunload = function () {
                        ws.close();
                        isOpenWebSocket = false;
                    }
                }