<?xml version="1.0" encoding="utf-8" ?> <StructureMap MementoStyle="Attribute"> <DefaultInstance PluginType="Wais.Service.IRegisterService,Wais.Service" PluggedType="Wais.Service.RegisterService,Wais.Service" Scope="Singleton" /> <DefaultInstance PluginType="Wais.Domain.IUserAccountRepository,Wais.Domain" PluggedType="Wais.Infrastructure.Data.EF.UserAccountRepository,Wais.Infrastructure.Data.EF" Scope="Singleton" /> <DefaultInstance PluginType="Wais.Infrastructure.IUnitOfWork,Wais.Infrastructure" PluggedType="Wais.Infrastructure.Data.EF.WaisEntities,Wais.Infrastructure.Data.EF" Scope="Singleton" /> </StructureMap>或是直接將container的設定寫在Global.asax的Application_Start裡如
ObjectFactory.Initialize(x =>
{
x.For<IUnitOfWork>().Use<WaisEntities>();
x.For<IUserAccountRepository>().Use<UserAccountRepository>();
x.For<IForgotPasswordRepository>().Use<ForgotPasswordRepository>();
x.For<IRegisterService>().Use<RegisterService>();
x.For<IUserAccountService>().Use<UserAccountService>();
x.For<IForgotPasswordService>().Use<ForgotPasswordService>();
});
將container設定寫在程式裡好處是有intellisense的支援，不過就必須把相依的實作也加入專案中，如此Web Application專案也會相依Data Access Layer或是Repository的實作專案，但一般我們會避免這種情況發生以免開發人員誤用。理想的狀況應該只相依介面專案，如Service Layer的介面專案。在這情況下使用設定檔方式設定IoC container即可免除上述困擾，但壞處就是要謹慎一點，有時打錯個字找半天都找不到問題在哪裡，實作類別更名時也得記得回來修改。還有一種做法是將IoC container的設定全放在另一個專案中，例如筆者有個函式庫專案名稱叫Wais.Web.DependencyInjection，裡面載入Service Layer及Repoistory所用到的介面及實作。而筆者的Web Application專案叫Wais.Web則加入Wais.Web.DependencyInjection為參考，如此只要在Application_Start中呼叫Wais.Web.DependencyInjection專案中某支方法便可初始化IoC container。
不過在ASP.NET MVC 4中如果要使用StructureMap在設定上有點小麻煩，為了要能初始化Controller，還需額外實作IDependencyResolver介面，在此我們不多談，直接使用nuget上所提供的StructureMap.MVC4。安裝完後會在專案中建立App_Start及DependencyResolution資料夾。App_Start下會有一個StructuremapMvc類別，而DependencyResolution下會有IoC、StructureMapDependencyResolver及StructureMapDependencyScope三個類別。我們只要到IoC這個類別中設定dependency即可，完全不需要在Global.asax做任何程式上的修改，StructureMap.MVC4即會透過WebActivator(StructuremapMvc這支類別)於應用程式啟動時自動載入。
using StructureMap;
using Wais.Domain;
using Wais.Infrastructure;
using Wais.Infrastructure.Data.EF;
using Wais.Service;
namespace Wais.Web.DependencyInjection.DependencyResolution
{
public static class IoC
{
public static IContainer Initialize()
{
ObjectFactory.Initialize(x =>
{
x.For<IUnitOfWork>().Use<WaisEntities>();
x.For<IUserAccountRepository>().Use<UserAccountRepository>();
x.For<IForgotPasswordRepository>().Use<ForgotPasswordRepository>();
x.For<IRegisterService>().Use<RegisterService>();
x.For<IUserAccountService>().Use<UserAccountService>();
x.For<IForgotPasswordService>().Use<ForgotPasswordService>();
});
return ObjectFactory.Container;
}
}
}
而在Controller或是Service做Constructor Injection時，StructureMap就會自動對應到相依的實作類別了，相當方便。private IRegisterService _registerService;
private IUserAccountService _userAccountService;
public HomeController(IRegisterService registerService, IUserAccountService userAccountService)
{
this._registerService = registerService;
this._userAccountService = userAccountService;
}
private IUserAccountRepository _userAccountRepository;
public RegisterService(IUserAccountRepository userAccountRepository)
{
if (userAccountRepository == null)
{
throw new ArgumentNullException("userAccountRepository");
}
this._userAccountRepository = userAccountRepository;
}
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