背景
系统开发最难的是职责的合理分配，或者叫：“如何合理的组织代码”，今天说一个关于这方面问题的示例，希望大家多批评。
示例背景
参考数据字典
需求
- OrderCode必须唯一。
- Total = Sum（Subtotal）。
- 订单有三种状态：【未提交】、【待审核】和【已审核】，合理的状态迁移有：【未提交】----》【待审核】和【待审核】----》【已审核】，只有处于【未提交】状态的订单能修改。
- 订单和订单项中的状态必须合法，规则自己定义。
示例实现
项目结构
- Application：应用层，负责领域逻辑的封装。主要角色：ApplicationService、CommandHandler。
- Boostrap：启动管理层，负责启动过程管理，如：注册Ioc、初始化配置。主要角色：BootstrapListener。
- Commands：命令层，是一个契约层。主要角色：Comamnd、DTO。
- Controllers：控制器层，边界层。主要角色：Controller。
- Domain：领域层，负责领域逻辑的组织。主要角色：Aggregate、Entity、ValueObject、Factory、DomainService、IRepository、IUnitOfWork。
- Events：事件层，是一个契约层，跨聚合流程可以采用。主要角色：Event。
- EventSubscribers：事件监听层。主要角色：EventSubscriber。
- Infrastructure：基础设施层。主要角色：Repository、QueryService、UnitOfWork。
- Query：查询层，为UI的查询提供服务，主要角色：QueryService。
项目整体采用简单的CQRS架构，Command端采用DDD组织，Query直接从数据库返回dynamic类型。Event可以用来处理跨聚合通信，也可以用来处理长事务或离线事务。
重点介绍的领域层
采用状态模式处理状态迁移。
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks; namespace Happy.Example.Domain.TestOrders
{
public interface ITestOrderState
{
void AddTestOrderDetail(TestOrderDetail testOrderDetail); void UpdateTestOrderDetail(Guid testOrderDetailId, decimal subtotal); void RemoveTestOrderDetail(Guid testOrderDetailId); void Commit(); void Verify(); string Status { get; } TestOrder TestOrder { set; }
}
}
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks; namespace Happy.Example.Domain.TestOrders
{
public partial class TestOrder
{
private abstract class TestOrderState : ITestOrderState
{
public virtual void AddTestOrderDetail(TestOrderDetail testOrderDetail)
{
this.ThrowInvalidOperationException();
} public virtual void UpdateTestOrderDetail(Guid testOrderDetailId, decimal subtotal)
{
this.ThrowInvalidOperationException();
} public virtual void RemoveTestOrderDetail(Guid testOrderDetailId)
{
this.ThrowInvalidOperationException();
} public virtual void Commit()
{
this.ThrowInvalidOperationException();
} public virtual void Verify()
{
this.ThrowInvalidOperationException();
} public abstract string Status { get; } public TestOrder TestOrder { protected get; set; } private void ThrowInvalidOperationException()
{
throw new InvalidOperationException(string.Format("处于【{0}】的订单不能执行此操作！", this.Status));
}
}
}
}
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks; namespace Happy.Example.Domain.TestOrders
{
public partial class TestOrder
{
private sealed class UnCommitted : TestOrderState
{
internal static readonly string UnCommittedStatus = "未提交"; public override void AddTestOrderDetail(TestOrderDetail testOrderDetail)
{
this.TestOrder.DoAddTestOrderDetail(testOrderDetail);
} public override void UpdateTestOrderDetail(Guid testOrderDetailId, decimal subtotal)
{
this.TestOrder.DoUpdateTestOrderDetail(testOrderDetailId, subtotal);
} public override void RemoveTestOrderDetail(Guid testOrderDetailId)
{
this.TestOrder.DoRemoveTestOrderDetail(testOrderDetailId);
} public override void Commit()
{
this.TestOrder.DoCommit();
} public override string Status
{
get { return UnCommittedStatus; }
}
}
}
}
采用封装集合手法处理Total的同步问题。
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks; using Happy.Domain;
using Happy.Domain.Tree;
using Happy.Infrastructure.ExtentionMethods;
using Happy.Example.Events.TestOrders; namespace Happy.Example.Domain.TestOrders
{
public partial class TestOrder : AggregateRoot<Guid>
{
private ITestOrderState _orderState; protected TestOrder() { } public TestOrder(string orderCode, string customer)
{
orderCode.MustNotNullAndNotWhiteSpace("orderCode");
customer.MustNotNullAndNotWhiteSpace("customer"); this.Id = Guid.NewGuid();
this.OrderCode = orderCode;
this.Customer = customer;
this.OrderState = TestOrderStateFactory.CreateUnCommittedTestOrderState(this);
this.TestOrderDetails = new List<TestOrderDetail>();
} public virtual System.String OrderCode { get; protected set; }
public virtual System.String Customer { get; protected set; }
public virtual System.Decimal Total { get; protected set; }
public virtual System.String Status { get; protected set; }
public virtual ICollection<TestOrderDetail> TestOrderDetails { get; protected set; } private ITestOrderState OrderState
{
get
{
if (_orderState == null)
{
_orderState = TestOrderStateFactory.Create(this, this.Status);
} return _orderState;
}
set
{
_orderState = value;
this.Status = value.Status;
}
} public void AddTestOrderDetail(TestOrderDetail testOrderDetail)
{
this.OrderState.AddTestOrderDetail(testOrderDetail);
} public void UpdateTestOrderDetail(Guid testOrderDetailId, decimal subtotal)
{
this.OrderState.UpdateTestOrderDetail(testOrderDetailId, subtotal);
} public void RemoveTestOrderDetail(Guid testOrderDetailId)
{
this.OrderState.RemoveTestOrderDetail(testOrderDetailId);
} public void Commit()
{
this.OrderState.Commit();
} public void Verify()
{
this.OrderState.Verify();
} private void DoAddTestOrderDetail(TestOrderDetail testOrderDetail)
{
this.TestOrderDetails.Add(testOrderDetail); this.Total += testOrderDetail.Subtotal;
} private void DoUpdateTestOrderDetail(Guid testOrderDetailId, decimal subtotal)
{
var testOrderDetail = this.TestOrderDetails.First(x => x.Id == testOrderDetailId); this.Total -= testOrderDetail.Subtotal;
testOrderDetail.Subtotal = subtotal;
this.Total += testOrderDetail.Subtotal;
} private void DoRemoveTestOrderDetail(Guid testOrderDetailId)
{
var testOrderDetail = this.TestOrderDetails.First(x => x.Id == testOrderDetailId); this.TestOrderDetails.Remove(testOrderDetail);
this.Total -= testOrderDetail.Subtotal;
} private void DoCommit()
{
this.OrderState = TestOrderStateFactory.CreatePendingVerificationTestOrderState(this);
} private void DoVerify()
{
this.OrderState = TestOrderStateFactory.CreateVerifiedTestOrderState(this); this.PublishEvent(new TestOrderVerified());
}
}
}
效果图
背景
写这个简单的Demo过程，遇到了很多小的决策，这篇文章就看做一个开头吧，后边重点介绍每个决策点，在一篇文章中真的很难说完，喜欢看代码的朋友，先去https://happy.codeplex.com/下载。