.net：SignalR通信服务

一、program添加服务

//添加SignalR服务
builder.Services.AddSignalR();

//映射通讯中心的请求路径
app.MapHub<ChatHub>("/Hubs");

二、工具类封装

  //注意前端接受参数关键词:ReceivePublicMsg

 public class ChatHub : Hub
 {
     public async Task SendMsg(string userId, string msg)
     {
         string sendMsg = $"服务端发起的消息，user={userId},msg={msg}";
         //服务端推送给所有客户端
         await Clients.All.SendAsync("ReceivePublicMsg", sendMsg);
         await Clients.User(userId).SendAsync(msg);
         //服务端推送给 除自已以外 的所有客户端
         await Clients.Others.SendAsync("ReceivePublicMsg", sendMsg); 
     }

     //客户端成功连接时，会触发此方法
     public override Task OnConnectedAsync()
     {
         var id = Context.ConnectionId;
         SendMsg(id, "测试消息");
         return Task.CompletedTask;
     }

     //客户端断开连接时，会触发此方法
     public override Task OnDisconnectedAsync(Exception? exception)
     {
         var id = Context.ConnectionId;
         return Task.CompletedTask;
     }
 }