加入MediatR包

<PackageReference Include="MediatR.Extensions.Microsoft.DependencyInjection" Version="10.0.1" />

program.cs中调用AddMediatR

builder.Services.AddMediatR(Assembly.GetExecutingAssembly());

定义消息实体和消息处理类

    public record PostNotification (string Title, string Body) : INotification;

    public class PostNotificationHandler1 : NotificationHandler<PostNotification>
    {
        protected override void Handle(PostNotification notification)
        {
            Console.WriteLine("1.received:" + notification);
        }
    }

    public class PostNotificationHandler2 : NotificationHandler<PostNotification>
    {
        protected override void Handle(PostNotification notification)
        {
            Console.WriteLine("2.received:" + notification);
        }
    }

注入IMediator，并调用Publish同步发送消息

    public class PersonController : ControllerBase
    {
        private IMediator Mediator { get; set; }

        public PersonController(IMediator mediator)
        {
            this.Mediator = mediator;
        }

        [HttpGet("add")]
        public ActionResult<int> Add(int i, int j)
        {
            Mediator.Publish(new PostNotification("ttt", "bbb"));
            return i + j;
        }
    }