SignalR WebSocket通讯机制_速读

来源博客园   2023-05-23 14:50:44

1、什么是SignalR


(相关资料图)

ASP.NET SignalR 是一个面向 ASP.NET 开发人员的库,可简化向应用程序添加实时 Web 功能的过程。 实时 Web 功能是让服务器代码在可用时立即将内容推送到连接的客户端,而不是让服务器等待客户端请求新数据。

SignalR使用的三种底层传输技术分别是Web Socket, Server Sent Events 和 Long Polling,它让你更好的关注业务问题而不是底层传输技术问题。

WebSocket是最好的最有效的传输方式, 如果浏览器或Web服务器不支持它的话(IE10之前不支持Web Socket), 就会降级使用SSE, 实在不行就用Long Polling。

(现在也很难找到不支持WebSocket的浏览器了,所以我们一般定义必须使用WebSocket)

2、我们做一个聊天室,实现一下SignalR前后端通讯

由简入深,先简单实现一下 

2.1 服务端Net5

using Microsoft.AspNetCore.Authorization;using Microsoft.AspNetCore.SignalR;using System;using System.Threading.Tasks;namespace ServerSignalR.Models{    public class ChatRoomHub:Hub    {        public override Task OnConnectedAsync()//连接成功触发        {            return base.OnConnectedAsync();        }        public Task SendPublicMsg(string fromUserName,string msg)//给所有client发送消息        {            string connId = this.Context.ConnectionId;            string str = $"[{DateTime.Now}]{connId}\r\n{fromUserName}:{msg}";            return this.Clients.All.SendAsync("ReceivePublicMsg",str);//发送给ReceivePublicMsg方法,这个方法由SignalR机制自动创建        }    }}

Startup添加

static string _myAllowSpecificOrigins = "MyAllowSpecificOrigins";        public void ConfigureServices(IServiceCollection services)        {            services.AddControllers();            services.AddSwaggerGen(c =>            {                c.SwaggerDoc("v1", new OpenApiInfo { Title = "ServerSignalR", Version = "v1" });            });            services.AddSignalR();            services.AddCors(options =>            {                options.AddPolicy(_myAllowSpecificOrigins, policy =>                {                    policy.WithOrigins("http://localhost:4200")                    .AllowAnyHeader().AllowAnyMethod().AllowCredentials();                });            });        }        // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.        public void Configure(IApplicationBuilder app, IWebHostEnvironment env)        {            if (env.IsDevelopment())            {                app.UseDeveloperExceptionPage();                app.UseSwagger();                app.UseSwaggerUI(c => c.SwaggerEndpoint("/swagger/v1/swagger.json", "ServerSignalR v1"));            }            app.UseCors(_myAllowSpecificOrigins);            app.UseHttpsRedirection();            app.UseRouting();            app.UseAuthorization();            app.UseEndpoints(endpoints =>            {                endpoints.MapControllers();                endpoints.MapHub("/Hubs/ChatRoomHub");            });        }

2.2 前端Angular

引入包

npm i --save @microsoft/signalr

ts:

import { Component, OnInit } from "@angular/core";import * as signalR from "@microsoft/signalr";import { CookieService } from "ngx-cookie-service";@Component({  selector: "app-home",  templateUrl: "./home.component.html",  styleUrls: ["./home.component.scss"]})export class HomeComponent implements OnInit {  msg = "";  userName="kxy"  public messages: string[] = [];  public hubConnection: signalR.HubConnection;  constructor(    private cookie: CookieService  ) {this.hubConnection=new signalR.HubConnectionBuilder()    .withUrl("https://localhost:44313/Hubs/ChatRoomHub",      {        skipNegotiation:true,//跳过三个协议协商        transport:signalR.HttpTransportType.WebSockets,//定义使用WebSocket协议通讯      }    )    .withAutomaticReconnect()    .build();    this.hubConnection.on("ReceivePublicMsg",msg=>{      this.messages.push(msg);      console.log(msg);    });  }  ngOnInit(): void {  }  JoinChatRoom(){    this.hubConnection.start()    .catch(res=>{      this.messages.push("连接失败");      throw res;    }).then(x=>{      this.messages.push("连接成功");    });  }  SendMsg(){    if(!this.msg){      return;    }    this.hubConnection.invoke("SendPublicMsg", this.userName,this.msg);  }}

这样就简单实现了SignalR通讯!!!

有一点值得记录一下

问题:强制启用WebSocket协议,有时候发生错误会被屏蔽,只是提示找不到/连接不成功

解决:可以先不跳过协商,调试完成后再跳过

3、引入Jwt进行权限验证

安装Nuget包:Microsoft.AspNetCore.Authentication.JwtBearer

Net5的,注意包版本选择5.x,有对应关系

Startup定义如下

using Microsoft.AspNetCore.Builder;using Microsoft.AspNetCore.Hosting;using Microsoft.Extensions.Configuration;using Microsoft.Extensions.DependencyInjection;using Microsoft.Extensions.Hosting;using Microsoft.OpenApi.Models;using ServerSignalR.Models;using System;using System.Collections.Generic;using System.Linq;using System.Threading.Tasks;using System.Text;using Microsoft.AspNetCore.Authentication.JwtBearer;using Microsoft.IdentityModel.Tokens;using JwtHelperCore;namespace ServerSignalR{    public class Startup    {        public Startup(IConfiguration configuration)        {            Configuration = configuration;        }        public IConfiguration Configuration { get; }        // This method gets called by the runtime. Use this method to add services to the container.        static string _myAllowSpecificOrigins = "MyAllowSpecificOrigins";        public void ConfigureServices(IServiceCollection services)        {            services.AddControllers();            services.AddSwaggerGen(c =>            {                c.SwaggerDoc("v1", new OpenApiInfo { Title = "ServerSignalR", Version = "v1" });            });            services.AddAuthentication(JwtBearerDefaults.AuthenticationScheme)                .AddJwtBearer(options =>                {                    options.RequireHttpsMetadata = false;//是否需要https                    options.TokenValidationParameters = new TokenValidationParameters                    {                        ValidateIssuer = false,//是否验证Issuer                        ValidateAudience = false,//是否验证Audience                        ValidateLifetime = true,//是否验证失效时间                        ValidateIssuerSigningKey = true,//是否验证SecurityKey                        IssuerSigningKey = new SymmetricSecurityKey(Encoding.UTF8.GetBytes("VertivSecurityKey001")),//拿到SecurityKey                    };                    options.Events = new JwtBearerEvents()//从url获取token                    {                        OnMessageReceived = context =>                        {                            if (context.HttpContext.Request.Path.StartsWithSegments("/Hubs/ChatRoomHub"))//判断访问路径                            {                                var accessToken = context.Request.Query["access_token"];//从请求路径获取token                                if (!string.IsNullOrEmpty(accessToken))                                    context.Token = accessToken;//将token写入上下文给Jwt中间件验证                            }                            return Task.CompletedTask;                        }                    };                }            );            services.AddSignalR();            services.AddCors(options =>            {                options.AddPolicy(_myAllowSpecificOrigins, policy =>                {                    policy.WithOrigins("http://localhost:4200")                    .AllowAnyHeader().AllowAnyMethod().AllowCredentials();                });            });        }        // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.        public void Configure(IApplicationBuilder app, IWebHostEnvironment env)        {            if (env.IsDevelopment())            {                app.UseDeveloperExceptionPage();                app.UseSwagger();                app.UseSwaggerUI(c => c.SwaggerEndpoint("/swagger/v1/swagger.json", "ServerSignalR v1"));            }            app.UseCors(_myAllowSpecificOrigins);            app.UseHttpsRedirection();            app.UseRouting();            //Token  授权、认证            app.UseErrorHandling();//自定义的处理错误信息中间件            app.UseAuthentication();//判断是否登录成功            app.UseAuthorization();//判断是否有访问目标资源的权限            app.UseEndpoints(endpoints =>            {                endpoints.MapHub("/Hubs/ChatRoomHub");                endpoints.MapControllers();            });        }    }}

红色部分为主要关注代码!!!

因为WebSocket无法自定义header,token信息只能通过url传输,由后端获取并写入到上下文

认证特性使用方式和http请求一致:

using Microsoft.AspNetCore.Authorization;using Microsoft.AspNetCore.SignalR;using System;using System.Linq;using System.Threading.Tasks;namespace ServerSignalR.Models{    [Authorize]//jwt认证    public class ChatRoomHub:Hub    {                public override Task OnConnectedAsync()//连接成功触发        {            return base.OnConnectedAsync();        }        public Task SendPublicMsg(string msg)//给所有client发送消息        {            var roles = this.Context.User.Claims.Where(x => x.Type.Contains("identity/claims/role")).Select(x => x.Value).ToList();//获取角色            var fromUserName = this.Context.User.Identity.Name;//从token获取登录人,而不是传入(前端ts方法的传入参数也需要去掉)            string connId = this.Context.ConnectionId;            string str = $"[{DateTime.Now}]{connId}\r\n{fromUserName}:{msg}";            return this.Clients.All.SendAsync("ReceivePublicMsg",str);//发送给ReceivePublicMsg方法,这个方法由SignalR机制自动创建        }    }}

然后ts添加

constructor(    private cookie: CookieService  ) {    var token  = this.cookie.get("spm_token");    this.hubConnection=new signalR.HubConnectionBuilder()    .withUrl("https://localhost:44313/Hubs/ChatRoomHub",      {        skipNegotiation:true,//跳过三个协议协商        transport:signalR.HttpTransportType.WebSockets,//定义使用WebSocket协议通讯        accessTokenFactory:()=> token.slice(7,token.length)//会自动添加Bearer头部,我这里已经有Bearer了,所以需要截掉      }    )    .withAutomaticReconnect()    .build();    this.hubConnection.on("ReceivePublicMsg",msg=>{      this.messages.push(msg);      console.log(msg);    });  }

4、私聊

Hub

using Microsoft.AspNetCore.Authorization;using Microsoft.AspNetCore.SignalR;using System;using System.Collections.Generic;using System.Threading.Tasks;namespace ServerSignalR.Models{    [Authorize]//jwt认证    public class ChatRoomHub:Hub    {        private static List _users = new List();        public override Task OnConnectedAsync()//连接成功触发        {            var userName = this.Context.User.Identity.Name;//从token获取登录人            _users.Add(new UserModel(userName, this.Context.ConnectionId));            return base.OnConnectedAsync();        }        public override Task OnDisconnectedAsync(Exception exception)        {            var userName = this.Context.User.Identity.Name;//从token获取登录人            _users.RemoveRange(_users.FindIndex(x => x.UserName == userName), 1);            return base.OnDisconnectedAsync(exception);        }        public Task SendPublicMsg(string msg)//给所有client发送消息        {            var fromUserName = this.Context.User.Identity.Name;            //var ss = this.Context.User!.FindFirst(ClaimTypes.Name)!.Value;            string str = $"[{DateTime.Now}]\r\n{fromUserName}:{msg}";            return this.Clients.All.SendAsync("ReceivePublicMsg",str);//发送给ReceivePublicMsg方法,这个方法由SignalR机制自动创建        }        public Task SendPrivateMsg(string destUserName, string msg)        {            var fromUser = _users.Find(x=>x.UserName== this.Context.User.Identity.Name);            var toUser = _users.Find(x=>x.UserName==destUserName);            string str = $"";            if (toUser == null)            {                msg = $"用户{destUserName}不在线";                str = $"[{DateTime.Now}]\r\n系统提示:{msg}";                return this.Clients.Clients(fromUser.WebScoketConnId).SendAsync("ReceivePrivateMsg", str);            }            str = $"[{DateTime.Now}]\r\n{fromUser.UserName}-{destUserName}:{msg}";            return this.Clients.Clients(fromUser.WebScoketConnId,toUser.WebScoketConnId).SendAsync("ReceivePrivateMsg", str);        }    }}

TS:

//加一个监听    this.hubConnection.on("ReceivePublicMsg", msg => {      this.messages.push("公屏"+msg);      console.log(msg);    });    this.hubConnection.on("ReceivePrivateMsg",msg=>{      this.messages.push("私聊"+msg);      console.log(msg);    });//加一个发送    if (this.talkType == 1)      this.hubConnection.invoke("SendPublicMsg", this.msg);    if (this.talkType == 3){      console.log("11111111111111");      this.hubConnection.invoke("SendPrivateMsg",this.toUserName, this.msg);    }

5、在控制器中使用Hub上下文

Hub链接默认30s超时,正常情况下Hub只会进行通讯,而不再Hub里进行复杂业务运算

如果涉及复杂业务计算后发送通讯,可以将Hub上下文注入外部控制器,如

namespace ServerSignalR.Controllers{    //[Authorize]    public class HomeController : Controller    {        private IHubContext _hubContext;        public HomeController(IHubContext hubContext)        {            _hubContext = hubContext;        }        [HttpGet("Welcome")]        public async Task> Welcome()        {            await _hubContext.Clients.All.SendAsync("ReceivePublicMsg", "欢迎");            return new ResultDataModel(true);        }    }}

至此,感谢关注!!

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