SignalR详解(简易聊天室案例)

Love The Way You Lie 2022-11-26 11:57 140阅读 0赞

# SignalR是什么？ #

按照官方的说法，signal能够方便的为应用提供实时的服务器端和客户端双向通信功能，相当于服务器端能够观察到客户端的实时更新，并且将这个更新广播推送，这是一个很有用的功能。SignalR适用场景如下

*  需要从服务器进行高频率更新的应用。 示例包括游戏、社交网络、投票、拍卖、地图和 GPS 应用。
 *  仪表板和监视应用。 示例包括公司仪表板、即时销售更新或旅行警报。
 *  协作应用。 协作应用的示例包括白板应用和团队会议软件。
 *  需要通知的应用。 社交网络、电子邮件、聊天、游戏、旅行警报和很多其他应用都需使用通知。

#  如何使用SignalR？ #

主要从客户端与服务器端来分解使用的流程：

**对于客户端(基于TypeScript)：需要创建SignalR的连接服务**

import "./css/main.css";
    import * as signalR from "@microsoft/signalr";
    
    const divMessages: HTMLDivElement = document.querySelector("#divMessages");
    const tbMessage: HTMLInputElement = document.querySelector("#tbMessage");
    const btnSend: HTMLButtonElement = document.querySelector("#btnSend");
    const username = new Date().getTime();
    
    // 创建与服务器端的连接，这个/hub即定位到后台的集线器文件目录
    const connection = new signalR.HubConnectionBuilder()
        .withUrl("/hub")
        .build();
    
    //这里写的一个消息名字为 "messageReceived" 对应于后台的发送消息名称
    connection.on("messageReceived", (username: string, message: string) => {
        let messages = document.createElement("div");
    
        messages.innerHTML =
            `<div class="message-author">${username}</div><div>${message}</div>`;
    
        divMessages.appendChild(messages);
        divMessages.scrollTop = divMessages.scrollHeight;
    });
    //开启连接，有时可以在中间加上then
    connection.start().catch(err => document.write(err));
    
    tbMessage.addEventListener("keyup", (e: KeyboardEvent) => {
        if (e.key === "Enter") {
            send();
        }
    });
    
    btnSend.addEventListener("click", send);
    //定义一个方法，发送消息定位到后台集线器的newMessage方法，并且置空输入框
    function send() {
        connection.send("newMessage", username, tbMessage.value)
            .then(() => tbMessage.value = "");
    }

发送消息也可以使用invoke

connection.invoke("方法名",发送的参数)

**对于服务器端：需要创建集线器Hub并且在启动项中配置SignalR的服务**

首先需要在启动项目中创建SignalR的服务

services.AddSignalR();

然后创建Hub集线器，另外还可以重写OnConnectedAsync和OnDisConnectedAsync方法来展示连接成功和断开连接时发生的动作

using Microsoft.AspNetCore.SignalR;
    using System.Threading.Tasks;
    
    namespace SignalRWebPack.Hubs
    {
        public class ChatHub : Hub
        {
            //此处对应前台的send方法中映射到newMessage
            public async Task NewMessage(long username, string message)
            {
                await Clients.All.SendAsync("messageReceived", username, message);
            //如果只想被人接收，而自己不接收，可以将All换成others
            }
        }
    }

前后台的关系流转可以用下图来表示

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzI5NjYwOTU3_size_16_color_FFFFFF_t_70][]

# 简单web聊天室 #

客户端代码：

<!DOCTYPE html>
    <html>
    <head>
        <meta charset="utf-8" />
        <title></title>
        
    </head>
    <body>
    
        <div>
            <input type="text" id="userName" placeholder="用户名"/>
            <input type="text" id="message" name="message" value="" placeholder="在此输入需要发送的信息" />
            <button type="button" id="sendBtn">发送</button>
        </div>
        <div>
            <div>
                <h3>聊天信息</h3>
            </div>
            <div>
                <ul id="messageList" style="height:340px"></ul>
            </div>
        </div>
    
        <script src="lib/aspnet/signalr/dist/browser/signalr.js"></script>
        <script type="text/javascript">
            //连接
            const connection = new signalR.HubConnectionBuilder()
                .withUrl("/myChatHub")
                .configureLogging(signalR.LogLevel.Information)
                .build();
            connection.start().catch(err => console.error(err.toString()));
    
            connection.on("SendMessage", (user, message) => {
                const encodedMsg = user + "说:" + message;
                const li = document.createElement("li");
                li.textContent = encodedMsg;
                document.getElementById("messageList").appendChild(li);
            });
    
            document.getElementById("sendBtn").addEventListener("click", function () {
                var user = document.getElementById('userName').value;
                var message = document.getElementById('message').value;
                connection.invoke("SendMessage", user, message).catch(err => console.error(err.toString()));
            });
        </script>
    </body>
    </html>

服务端代码：

using Microsoft.AspNetCore.SignalR;
    using System;
    using System.Collections.Generic;
    using System.Linq;
    using System.Threading.Tasks;
    
    namespace webchat
    {
        public class MychatHub:Hub
        {
            public async Task SendMessage(string userName,string message)
            {
                await Clients.All.SendAsync("SendMessage", userName, message);
            }
            public override Task OnConnectedAsync()
            {
                return base.OnConnectedAsync();
            }
            public override Task OnDisconnectedAsync(Exception exception)
            {
                return base.OnDisconnectedAsync(exception);
            }
        }
    }

在starup.cs文件中添加SignalR服务以及路由

services.AddSignalR();

app.UseSignalR(route =>
                {
                    route.MapHub<MychatHub>("/myChathub");
                });

聊天室效果如下

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzI5NjYwOTU3_size_16_color_FFFFFF_t_70 1][]

参考博客：

[https://www.cnblogs.com/cgzl/p/9515516.html][https_www.cnblogs.com_cgzl_p_9515516.html]

[https://blog.csdn.net/qq\_36825683/article/details/80758988?utm\_medium=distribute.pc\_relevant.none-task-blog-BlogCommendFromMachineLearnPai2-2.edu\_weight&depth\_1-utm\_source=distribute.pc\_relevant.none-task-blog-BlogCommendFromMachineLearnPai2-2.edu\_weight][https_blog.csdn.net_qq_36825683_article_details_80758988_utm_medium_distribute.pc_relevant.none-task-blog-BlogCommendFromMachineLearnPai2-2.edu_weight_depth_1-utm_source_distribute.pc_relevant.none-task-blog-BlogCommendFromMachineLearnPai2-2.edu_weight]

[https://www.cnblogs.com/yaopengfei/category/1202154.html][https_www.cnblogs.com_yaopengfei_category_1202154.html] （从websocket谈到signalR)

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzI5NjYwOTU3_size_16_color_FFFFFF_t_70]: /images/20221124/68b846cded2f42e995a99a38936a0f6c.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzI5NjYwOTU3_size_16_color_FFFFFF_t_70 1]: /images/20221124/77259b45fe22406d9477caaac56426f1.png
[https_www.cnblogs.com_cgzl_p_9515516.html]: https://www.cnblogs.com/cgzl/p/9515516.html
[https_blog.csdn.net_qq_36825683_article_details_80758988_utm_medium_distribute.pc_relevant.none-task-blog-BlogCommendFromMachineLearnPai2-2.edu_weight_depth_1-utm_source_distribute.pc_relevant.none-task-blog-BlogCommendFromMachineLearnPai2-2.edu_weight]: https://blog.csdn.net/qq_36825683/article/details/80758988?utm_medium=distribute.pc_relevant.none-task-blog-BlogCommendFromMachineLearnPai2-2.edu_weight&depth_1-utm_source=distribute.pc_relevant.none-task-blog-BlogCommendFromMachineLearnPai2-2.edu_weight
[https_www.cnblogs.com_yaopengfei_category_1202154.html]: https://www.cnblogs.com/yaopengfei/category/1202154.html