一、前言
上次讲SignalR还是在《在ASP.NET Core下使用SignalR技术》文章中提到，ASP.NET Core 1.x.x 版本发布中并没有包含SignalR技术和开发计划中。时间过得很快，MS已经发布了.NET Core 2.0 Preview 2 预览版，距离正式版已经不远了，上文中也提到过在ASP.NET Core 2.0中的SignalR将做为重要的组件与MVC等框架一起发布。它的开发团队也兑现了承诺，使用TypeScript对它的javascript客户端进行重写，服务端方面也会贴近ASP.NET Core的开发方式，比如会集成到ASP.NET Core依赖注入框架中。
二、环境搭建
要在ASP.NET Core 2.0中使用SignalR，要先引用Microsoft.AspNetCore.SignalR 、 Microsoft.AspNetCore.SignalR.Http 两个Package包。
目前ASP.NET Core 2.0与SignalR还都是Preview版本，所以NUGET上也找不到SignalR的程序包，想添加引用我们就得去MyGet上去找找。既然要用MyGet的话，就要为项目添加NuGet源了。
1.添加NuGet源
在程序根目录新建一个命为NuGet.Config的文件内容如下：
<?xml version="1.0" encoding="utf-8"?>
<configuration>
<packageSources>
<clear/>
<add key="aspnetcidev" value="https://dotnet.myget.org/F/aspnetcore-ci-dev/api/v3/index.json"/>
<add key="api.nuget.org" value="https://api.nuget.org/v3/index.json"/>
</packageSources>
</configuration>
2.编辑项目文件csproj
添加上面提到的两个包的引用：
<PackageReference Include="Microsoft.AspNetCore.All" Version="2.0.0-preview3-26040" />
<PackageReference Include="Microsoft.AspNetCore.SignalR" Version="1.0.0-preview3-26037" />
<PackageReference Include="Microsoft.AspNetCore.SignalR.Http" Version="1.0.0-preview3-26037" />
我在这个示例里使用的是目前的最高,当然版本号每天都有可能发生变化，最新版本的SignalR，是不兼容.NET Core SDK 2.0 Preview 1中默认创建项目时Microsoft.AspNetCore.All这个包的版本的，这里也修改修改一下版本号为：Microsoft.AspNetCore.All 2.0.0-preview3-26040。
当然也可以用dotnet cli 来添加包引用：
dotnet add package Microsoft.AspNetCore.SignalR --version 1.0.0-preview3-26037 --source https://dotnet.myget.org/F/aspnetcore-dev/api/v3/index.json
dotnet add package Microsoft.AspNetCore.SignalR.Http --version 1.0.0-preview3-26037 --source https://dotnet.myget.org/F/aspnetcore-dev/api/v3/index.json
3.添加配置代码
我们需要在Startup类中的 ConfigureServices方法中添加如下代码：
public void ConfigureServices(IServiceCollection services)
{
services.AddSignalR();
}
在Startup类中的Configure方法中添加如下代码：
public void Configure(IApplicationBuilder app, IHostingEnvironment env)
{
app.UseStaticFiles();
app.UseSignalR(routes =>
{
routes.MapHub<Chat>("hubs");
});
}
4.添加一个HUB类
public class Chat : Hub
{
public override async Task OnConnectedAsync()
{
await Clients.All.InvokeAsync("Send", $"{Context.ConnectionId} joined");
}
public override async Task OnDisconnectedAsync(Exception ex)
{
await Clients.All.InvokeAsync("Send", $"{Context.ConnectionId} left");
}
public Task Send(string message)
{
return Clients.All.InvokeAsync("Send", $"{Context.ConnectionId}: {message}");
}
public Task SendToGroup(string groupName, string message)
{
return Clients.Group(groupName).InvokeAsync("Send", $"{Context.ConnectionId}@{groupName}: {message}");
}
public async Task JoinGroup(string groupName)
{
await Groups.AddAsync(Context.ConnectionId, groupName);
await Clients.Group(groupName).InvokeAsync("Send", $"{Context.ConnectionId} joined {groupName}");
}
public async Task LeaveGroup(string groupName)
{
await Groups.RemoveAsync(Context.ConnectionId, groupName);
await Clients.Group(groupName).InvokeAsync("Send", $"{Context.ConnectionId} left {groupName}");
}
public Task Echo(string message)
{
return Clients.Client(Context.ConnectionId).InvokeAsync("Send", $"{Context.ConnectionId}: {message}");
}
}
5.客户端支持
在wwwroot目录下创建一个名为chat.html的Html静态文件，内容如下：
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8" />
<title></title>
</head>
<body>
<h1 id="head1"></h1>
<div>
<select id="formatType">
<option value="json">json</option>
<option value="line">line</option>
</select>
<input type="button" id="connect" value="Connect" />
<input type="button" id="disconnect" value="Disconnect" />
</div>
<h4>To Everybody</h4>
<form class="form-inline">
<div class="input-append">
<input type="text" id="message-text" placeholder="Type a message, name or group" />
<input type="button" id="broadcast" class="btn" value="Broadcast" />
<input type="button" id="broadcast-exceptme" class="btn" value="Broadcast (All Except Me)" />
<input type="button" id="join" class="btn" value="Enter Name" />
<input type="button" id="join-group" class="btn" value="Join Group" />
<input type="button" id="leave-group" class="btn" value="Leave Group" />
</div>
</form>
<h4>To Me</h4>
<form class="form-inline">
<div class="input-append">
<input type="text" id="me-message-text" placeholder="Type a message" />
<input type="button" id="send" class="btn" value="Send to me" />
</div>
</form>
<h4>Private Message</h4>
<form class="form-inline">
<div class="input-prepend input-append">
<input type="text" name="private-message" id="private-message-text" placeholder="Type a message" />
<input type="text" name="user" id="target" placeholder="Type a user or group name" />
<input type="button" id="privatemsg" class="btn" value="Send to user" />
<input type="button" id="groupmsg" class="btn" value="Send to group" />
</div>
</form>
<ul id="message-list"></ul>
</body>
</html>
<script src="signalr-client.js"></script>
<script src="utils.js"></script>
<script>
var isConnected = false;
function invoke(connection, method, ...args) {
if (!isConnected) {
return;
}
var argsArray = Array.prototype.slice.call(arguments);
connection.invoke.apply(connection, argsArray.slice(1))
.then(result => {
console.log("invocation completed successfully: " + (result === null ? '(null)' : result));
if (result) {
addLine('message-list', result);
}
})
.catch(err => {
addLine('message-list', err, 'red');
});
}
function getText(id) {
return document.getElementById(id).value;
}
let transportType = signalR.TransportType[getParameterByName('transport')] || signalR.TransportType.WebSockets;
document.getElementById('head1').innerHTML = signalR.TransportType[transportType];
let connectButton = document.getElementById('connect');
let disconnectButton = document.getElementById('disconnect');
disconnectButton.disabled = true;
var connection;
click('connect', event => {
connectButton.disabled = true;
disconnectButton.disabled = false;
let http = new signalR.HttpConnection(`http://${document.location.host}/hubs`, { transport: transportType });
connection = new signalR.HubConnection(http);
connection.on('Send', msg => {
addLine('message-list', msg);
});
connection.onClosed = e => {
if (e) {
addLine('message-list', 'Connection closed with error: ' + e, 'red');
}
else {
addLine('message-list', 'Disconnected', 'green');
}
}
connection.start()
.then(() => {
isConnected = true;
addLine('message-list', 'Connected successfully', 'green');
})
.catch(err => {
addLine('message-list', err, 'red');
});
});
click('disconnect', event => {
connectButton.disabled = false;
disconnectButton.disabled = true;
connection.stop()
.then(() => {
isConnected = false;
});
});
click('broadcast', event => {
let data = getText('message-text');
invoke(connection, 'Send', data);
});
click('join-group', event => {
let groupName = getText('message-text');
invoke(connection, 'JoinGroup', groupName);
});
click('leave-group', event => {
let groupName = getText('message-text');
invoke(connection, 'LeaveGroup', groupName);
});
click('groupmsg', event => {
let groupName = getText('target');
let message = getText('private-message-text');
invoke(connection, 'SendToGroup', groupName, message);
});
click('send', event => {
let data = getText('me-message-text');
invoke(connection, 'Echo', data);
});
</script>
值得注意的是，你可能会发现，目前找不到signalr-client.js这个文件，它是怎么来的呢，有两种方式：
第1种是通过下载SignalR的源代码，找到Client-TS项目，对TypeScript进行编译可以得到。
第2种比较简单通过Npm可以在线获取：
npm install signalr-client --registry https://dotnet.myget.org/f/aspnetcore-ci-dev/npm/
三、最后
附上一个可用的Demo：https://github.com/maxzhang1985/AspNetCore.SignalRDemo
GitHub：https://github.com/maxzhang1985/YOYOFx 如果觉还可以请Star下， 欢迎一起交流。
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