洋葱架构

1. 内层部分比外层更抽象(内层接口，外层实现)。
2. 外层的代码只能调用内层的代码，内层的代码可以通过依赖注入的形式来间接调用外层的代码

简单的例子，引用依赖图

demo

1. 接口类库
   EmailInfo

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;namespace Intf
{public class EmailInfo{public string Email { get; set; }public string Subject { get; set; }public string Body { get; set; }public EmailInfo(string email,string subject,string body){Email = email;  Subject = subject;Body = body;}}
}

IGenerateMessage

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;namespace Intf
{public interface IGenerateMessage{public IEnumerable<EmailInfo> GenerateEmail();}
}

ISendMessage

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;namespace Intf
{public interface ISendMessage{public Task SendMessageAsync(EmailInfo emailInfo);}
}

Mybusiness 这是实现业务的地方，注入两个接口，一个是获取数据，一个是发送信息，实现均在控制台工程实现

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;namespace Intf
{public class Mybusiness{public IGenerateMessage GenerateMessage { get; set; }public ISendMessage SendMessage { get; set; }public Mybusiness(IGenerateMessage generateMessage, ISendMessage sendMessage){GenerateMessage = generateMessage;SendMessage = sendMessage;}public async Task DoIt(){var items = GenerateMessage.GenerateEmail();foreach (var item in items){await SendMessage.SendMessageAsync(item);await Task.Delay(1000);}}}
}

2. 控制台工程
   GenerateMessage

using Intf;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;namespace Onion
{internal class GenerateMessage : IGenerateMessage{public IEnumerable<EmailInfo> GenerateEmail(){for (int i = 0; i < 5; i++){yield return new EmailInfo("1.com", "你好", "你好");}}}
}

MyEmailSender

using Intf;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;namespace Onion
{internal class MyEmailSender : ISendMessage{public Task SendMessageAsync(EmailInfo emailInfo){Console.WriteLine($"{emailInfo.Email} {emailInfo.Subject} {emailInfo.Body}");return Task.CompletedTask;}}
}

program

//依赖注入
using Intf; //类库名称
using Microsoft.Extensions.DependencyInjection;//
using Onion;//控制台工程名称ServiceCollection service =  new ServiceCollection();service.AddScoped<IGenerateMessage, GenerateMessage>();service.AddScoped<ISendMessage, MyEmailSender>();service.AddScoped<Mybusiness>();
var sp =  service.BuildServiceProvider();Mybusiness business = sp.GetRequiredService<Mybusiness>();business.DoIt();Console.WriteLine("Hello, World!");