具有自定义返回类型的通用CQRS查询处理程序

using System;
using System.Collections.Generic;
using System.Threading.Tasks;

// 定义一个通用的查询接口
public interface IQuery<TResult>
{
}

// 定义一个通用的查询处理程序接口
public interface IQueryHandler<in TQuery, TResult> where TQuery : IQuery<TResult>
{
    Task<TResult> HandleAsync(TQuery query);
}

// 具体的查询类
public class GetUserQuery : IQuery<User>
{
    public int UserId { get; set; }
}

// 具体的查询处理程序类
public class GetUserQueryHandler : IQueryHandler<GetUserQuery, User>
{
    public async Task<User> HandleAsync(GetUserQuery query)
    {
        // 模拟从数据库获取用户信息
        await Task.Delay(100);
        return new User { Id = query.UserId, Name = "John Doe" };
    }
}

// 用户类
public class User
{
    public int Id { get; set; }
    public string Name { get; set; }
}

// 查询处理程序注册和解析类
public class QueryProcessor
{
    private readonly Dictionary<Type, object> _handlers = new Dictionary<Type, object>();

    public void RegisterHandler<TQuery, TResult>(IQueryHandler<TQuery, TResult> handler) where TQuery : IQuery<TResult>
    {
        _handlers[typeof(TQuery)] = handler;
    }

    public async Task<TResult> ProcessAsync<TQuery, TResult>(TQuery query) where TQuery : IQuery<TResult>
    {
        var handlerType = typeof(IQueryHandler<,>).MakeGenericType(query.GetType(), typeof(TResult));
        var handler = _handlers[handlerType];
        return await ((dynamic)handler).HandleAsync((dynamic)query);
    }
}

// 示例使用
public class Program
{
    public static async Task Main(string[] args)
    {
        var queryProcessor = new QueryProcessor();
        queryProcessor.RegisterHandler(new GetUserQueryHandler());

        var query = new GetUserQuery { UserId = 1 };
        var user = await queryProcessor.ProcessAsync(query);

        Console.WriteLine($"User: {user.Name}");
    }
}

queryProcessor.RegisterHandler(new GetUserQueryHandler());