.net core 使用SignalR实现实时通信

这几天在研究SignalR，网上大部分的例子都是聊天室，我的需求是把服务端的信息发送给前端展示。并且需要实现单个用户推送。

用户登录我用的是ClaimsIdentity，这里就不多解释，如果不是很了解，可以看这篇文章https://www.cnblogs.com/zhangjd/p/11332558.html

推荐https://www.cnblogs.com/laozhang-is-phi/p/netcore-vue-signalr.html#tbCommentBody这个博客，写的很详细，并且附有Dome

一、后端实现

1、引用SignalR包

Install-Package Microsoft.AspNetCore.SignalR

2、声明一个类来记录用户的连接信息。

     public class SignalRModel
     {
         public static Dictionary<string, SignalRStatus> StaticList = new Dictionary<string, SignalRStatus>();
         public static Dictionary<string, string> SignalRList { get; set; } = new Dictionary<string, string>();
     }

3、声明Hub，这里我重写了连接和断开方法，用来绑定用户和连接的ConnectionId。（这个比较复杂，是因为我程序中执行的第三方程序，需要实时输出当前执行的程序的日志。但是调用的执行不可能直接写在控制器里，这样调用我没办法获取当前用户的登录Id。然后我就在发起连接和断开连接的方法处理了。）

 public class ChatHub : Hub
     {
         /// <summary>
         /// 连接成功
         /// </summary>
         /// <returns></returns>
         public override Task OnConnectedAsync()
         {
             var id = this.Context.ConnectionId;
             var claimNameIdentifier = this.Context.User.Claims.FirstOrDefault(s => s.Type == ClaimTypes.NameIdentifier)?.Value;
             SignalRModel.SignalRList.Add(id, claimNameIdentifier);
             if (SignalRModel.StaticList.Any(s => s.Key.Equals(claimNameIdentifier)))
             {
                 SignalRModel.StaticList.Remove(claimNameIdentifier);
             }
             SignalRModel.StaticList.Add(claimNameIdentifier, SignalRStatus.Open);
             return base.OnConnectedAsync();
         }
         /// <summary>
         /// 断开连接
         /// </summary>
         public override Task OnDisconnectedAsync(Exception exception)
         {
             var id = this.Context.ConnectionId;
             var claimNameIdentifier = this.Context.User.Claims.FirstOrDefault(s => s.Type == ClaimTypes.NameIdentifier)?.Value;
             SignalRModel.SignalRList.Remove(id);
             SignalRModel.StaticList.Remove(claimNameIdentifier);
             return base.OnDisconnectedAsync(exception);
         }
         /// <summary>
         /// 发送消息
         /// </summary>
         /// <param name="user"></param>
         /// <param name="message"></param>
         /// <returns></returns>
         public async Task SendMessage(string user, string message)
         {
             await Clients.All.SendAsync("ReceiveMessage", user, message);
         }
     }

4、在程序启动的时候，把记录用户连接信息的类，注入成单例，保存用户和连接的对应关系，方便单个通信。

   services.AddSingleton<SignalRModel>(provider =>
   {
       return new SignalRModel();
   });

5、配置

1)、在ConfigureServices中加入

services.AddSignalR();//要写在addmvc()前面
services.AddMvc().SetCompatibilityVersion(CompatibilityVersion.Version_2_2);

2)、在Configure中加入

app.UseMvc();
app.UseSignalR(routes =>
{
   routes.MapHub<ChatHub>("/api/chatHub");
});//要写在UseMvc后面

6、这里我写了后端两个接口来发送消息，区别在于第一个是群发，第二个是针对一个连接发送的。

         [HttpGet("SendAll")]
         public IActionResult SendAll()
         {
             _hubContext.Clients.All.SendAsync("ReceiveUpdate", "推送全部人").Wait();
             return Ok("推送全部人");
         }
         [HttpGet("SendOnly")]
         public IActionResult SendOnly()
         {
             var claimNameIdentifier = User.Claims.FirstOrDefault(s => s.Type == ClaimTypes.NameIdentifier)?.Value;
             if (string.IsNullOrEmpty(claimNameIdentifier))
             {
                 return Ok(new { code = ResultCode.NotLogin, message = "用户未登陆！" });
             }
             _hubContext.Clients.Clients(claimNameIdentifier).SendAsync("ReceiveUpdate", DateTime.Now).Wait();
             return Ok("推送当前登录用户");
         }

7、我项目实际用到的是这样的，给当前登录用户发送日志消息，判断连接是否断开，如果断开需要获取前面写的日志，发送给前端之后，把连接的状态改成连接中，后面就正常发送。

    foreach (var item in SignalRModel.SignalRList.Where(s => s.Value.Equals(userId.ToString())).ToList())
    {
       if (SignalRModel.StaticList.Any(s => s.Key.Equals(userId.ToString()) && s.Value == SignalRStatus.Open))
       {
          if (SignalRModel.StaticList.Any(s => s.Key.Equals(userId.ToString())))
          {
               SignalRModel.StaticList.Remove(userId.ToString());
          }
          SignalRModel.StaticList.Add(userId.ToString(), SignalRStatus.working);
          _hubContext.Clients.Client(item.Key).SendAsync("ReceiveUpdate", FileHelper.ReadFile(Path.Combine(filePath, "tls_simplify.txt"), Encoding.UTF8)).Wait();
       }
       _hubContext.Clients.Client(item.Key).SendAsync("ReceiveUpdate", args.Data).Wait();
    }

二、前端vue

1、安装依赖包

npm install @aspnet/signalr

2、示例页面

 <template>
     <section>
         <div style="display: none1">
             <el-form ref="form" label-width="80px" @submit.prevent="onSubmit"
                      style="margin:20px;width:60%;min-width:600px;">
                 <el-form-item label="用户名">
                     <el-input v-model="userName"></el-input>
                 </el-form-item>
                 <el-form-item label="密码">
                     <el-input v-model="userMessage"></el-input>
                 </el-form-item>
             </el-form>
             <ul v-for="(item, index) in messages" v-bind:key="index + 'itemMessage'">
                 <li><b>Name: </b>{{item.user}}</li>
                 <li><b>Message: </b>{{item.message}}</li>
             </ul>
             <p>
             <b>后台发送消息: </b>{{this.postMessage}}
             </p>
             <el-button type="primary" @click="submitCard">登录</el-button>
             <el-button type="primary" @click="getLogs">查询</el-button>
         </div>
     </section>
 </template>

 <script>

     import * as signalR from "@aspnet/signalr";

     export default {
       name: 'Dashboard',
         data() {
             return {
                 filters: {
                     LinkUrl: ''
                 },
                 listLoading: true,
                 postMessage: "",
                 userName: "Tom",
                 userMessage: "",
                 connection: "",
                 messages: [],
                 t: ""

             }
         },
         methods: {
             getRoles() {
                 let thisvue=this;
                 let para = {
                     page: this.page,
                     key: this.filters.LinkUrl
                 };
                 this.listLoading = true;
                 thisvue.connection.start().then(() => {
                    thisvue.connection.invoke('GetLatestCount', ).catch(function (err) {
                    return console.error(err);
                 });
             });
             },
             submitCard: function () {
                 if (this.userName && this.userMessage) {
                     this.connection.invoke('SendMessage', this.userName, this.userMessage).catch(function (err) {
                         return console.error(err);
                     });

                 }
             },
             getLogs: function () {
                 this.listLoading = true;
                 this.connection.invoke('GetLatestCount', ).catch(function (err) {
                     return console.error(err);
                 });
             }
         },
         created: function () {
             let thisVue = this;
             thisVue.connection = new signalR.HubConnectionBuilder()
                 .withUrl('http://localhost:5000/api/chatHub')
                 .configureLogging(signalR.LogLevel.Information)
                 .build();
             thisVue.connection.on('ReceiveMessage', function (user, message) {
                 thisVue.messages.push({user, message});
             });

             thisVue.connection.on('ReceiveUpdate', function (update) {
                 console.info('update success!')
                 thisVue.listLoading = false;
                 thisVue.postMessage = update;
                 window.clearInterval(this.t)
             })
         },
         mounted() {
             this.getRoles();
         },
         beforeDestroy() {
             window.clearInterval(this.t)
             this.connection.stop();
         }
     }
 </script>

 <style scoped>
     .demo-table-expand {
         font-size: ;
     }

     .demo-table-expand label {
         width: 90px;
         color: #99a9bf;
     }

     .demo-table-expand .el-form-item {
         margin-right: ;
         margin-bottom: ;
         width: %;
     }

     .EXC {
         color: red;
     }
 </style>