獲取 IHubContext 的實例
在 ASP.NET Core SignalR，您可以訪問的實例IHubContext通過依賴關係注入。 您可以注入的實例IHubContext到控制器、 中間件或其他 DI 服務。 使用的實例將消息發送到客戶端。
注入控制器中的 IHubContext 實例有兩種方法
一：.直接將實例注入到IHubContext添加到控制器的構造函數：
具體步驟：
1.直接將實例注入到IHubContext添加到控制器的構造函數：
public class HomeController : Controller
{
private readonly IHubContext<ChatHub> _hubContext;
public HomeController(IHubContext<ChatHub> chatHubContext)
{
_hubContext = chatHubContext;
}
public async Task<IActionResult> Index()
{
return View();
}
}
2.配置 SignalR
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.
public void ConfigureServices(IServiceCollection services)
{
services.Configure<CookiePolicyOptions>(options =>
{
// This lambda determines whether user consent for non-essential cookies is needed for a given request.
options.CheckConsentNeeded = context => true;
options.MinimumSameSitePolicy = SameSiteMode.None;
});
services.AddSignalR();
services.AddMvc().SetCompatibilityVersion(CompatibilityVersion.Version_2_1);
}
// This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
public void Configure(IApplicationBuilder app, IHostingEnvironment env)
{
if (env.IsDevelopment())
{
app.UseDeveloperExceptionPage();
}
else
{
app.UseExceptionHandler("/Home/Error");
}
app.UseStaticFiles();
app.UseCookiePolicy();
app.UseSignalR(routes =>
{
routes.MapHub<ChatHub>("/chatHub");
});
app.UseMvc(routes =>
{
routes.MapRoute(
name: "default",
template: "{controller=Home}/{action=Index}/{id?}");
});
}
}
3.生成Home視圖，代碼：
@{
Layout = null;
}
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<meta name="viewport" content="initial-scale=1.0,maximum-scale=1.0,user-scalable=no">
<title>Test</title>
<script src="~/lib/jquery/dist/jquery.js"></script>
</head>
<body >
<div class="container">
<div class="row"> </div>
<div class="row">
<div class="col-6"> </div>
<div class="col-6">
User..........<input type="text" id="userInput" />
<br />
Message...<input type="text" id="messageInput" />
<input type="button" id="sendButton" value="Send Message" />
</div>
</div>
<div class="row">
<div class="col-12">
<hr />
</div>
</div>
<div class="row">
<div class="col-6"> </div>
<div class="col-6">
<ul id="messagesList"></ul>
</div>
</div>
</div>
<script src="~/lib/signalr/dist/browser/signalr.js"></script>
<script type="text/javascript">
const connection = new signalR.HubConnectionBuilder()
.withUrl("/chatHub")
.build();
connection.on("ReceiveMessage", (user, message, id) => {
const encodedMsg = user + " says " + message + " id:" + id ;
const li = document.createElement("li");
li.textContent = encodedMsg;
document.getElementById("messagesList").appendChild(li);
});
document.getElementById("sendButton").addEventListener("click", event => {
const user = document.getElementById("userInput").value;
const message = document.getElementById("messageInput").value;
connection.invoke("SendMessage", user, message).catch(err => console.error(err));
event.preventDefault();
});
connection.start().catch(err => console.error(err));
//connection.start();
</script>
</body>
</html>
4.運行結果：
二：注入強類型化 HubContext
1.將強類型注入到IHubContext添加到控制器的構造函數：
public class HomeController : Controller
{
// private readonly IHubContext<ChatHub> _hubContext;
private IHubContext<StronglyTypedChatHub, IChatClient> _hubContext { get; }
public HomeController(IHubContext<StronglyTypedChatHub, IChatClient> chatHubContext)
{
_hubContext = chatHubContext;
}
public async Task<IActionResult> Index()
{
return View();
}
}
2.配置 SignalR
public void Configure(IApplicationBuilder app, IHostingEnvironment env)
{
if (env.IsDevelopment())
{
app.UseDeveloperExceptionPage();
}
else
{
app.UseExceptionHandler("/Home/Error");
}
app.UseStaticFiles();
app.UseCookiePolicy();
app.UseSignalR(routes =>
{
routes.MapHub<StronglyTypedChatHub>("/chatHub");
});
app.UseMvc(routes =>
{
routes.MapRoute(
name: "default",
template: "{controller=Home}/{action=Index}/{id?}");
});
}
3.生成Home視圖，代碼：
@{
Layout = null;
}
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<meta name="viewport" content="initial-scale=1.0,maximum-scale=1.0,user-scalable=no">
<title>Test</title>
<script src="~/lib/jquery/dist/jquery.js"></script>
</head>
<body >
<div class="container">
<div class="row"> </div>
<div class="row">
<div class="col-6"> </div>
<div class="col-6">
User..........<input type="text" id="userInput" />
<br />
Message...<input type="text" id="messageInput" />
<input type="button" id="sendButton" value="Send Message" />
</div>
</div>
<div class="row">
<div class="col-12">
<hr />
</div>
</div>
<div class="row">
<div class="col-6"> </div>
<div class="col-6">
<ul id="messagesList"></ul>
</div>
</div>
</div>
<script src="~/lib/signalr/dist/browser/signalr.js"></script>
<script type="text/javascript">
const connection = new signalR.HubConnectionBuilder()
.withUrl("/chatHub")
.build();
connection.on("ReceiveMessage", (user, message, id) => {
const encodedMsg = user + " says " + message + " id:" + id ;
const li = document.createElement("li");
li.textContent = encodedMsg;
document.getElementById("messagesList").appendChild(li);
});
document.getElementById("sendButton").addEventListener("click", event => {
const user = document.getElementById("userInput").value;
const message = document.getElementById("messageInput").value;
connection.invoke("SendMessage", user, message).catch(err => console.error(err));
event.preventDefault();
});
connection.start().catch(err => console.error(err));
//connection.start();
</script>
</body>
</html>
4.運行結果：
