ASP.NET MVC4 + EF5 + EasyUI + Unity2.x 後台管理系統實戰（六）：Unity 2.x 依賴注入實作與原始碼

前言

依賴注入（DI）與控制反轉（IoC）是企業級應用架構的核心模式。本講將實際展示如何在專案中整合 Unity 2.x 容器，採用建構函式注入與執行時期注入方式，並提供完整原始碼下載。

Unity 套件安裝與專案結構

可從 CodePlex 或 NuGet 取得 Unity 2.x。在方案中建立 App.Core 核心類別庫，參考 Microsoft.Practices.Unity.dll、System.Web.Mvc、System.Web 以及專案內的 BLL、IBLL、DAL、IDAL 等介面與實作專案。

依賴註冊類別

using System;
using Microsoft.Practices.Unity;
using App.BLL;
using App.DAL;
using App.IBLL;
using App.IDAL;

namespace App.Core {
  public class DependencyRegisterType {
    public static void Container_Sys(ref UnityContainer container) {
      container.RegisterType<ISysSampleBLL, SysSampleBLL>();
      container.RegisterType<ISysSampleRepository, SysSampleRepository>();
    }
  }
}

自訂 Dependency Resolver

實作 IDependencyResolver 介面，管理每個 HTTP 請求的子容器生命週期：

using System;
using System.Web;
using System.Web.Mvc;
using Microsoft.Practices.Unity;

namespace App.Core {
  public class UnityDependencyResolver : IDependencyResolver {
    private const string HttpContextKey = "perRequestContainer";
    private readonly IUnityContainer _container;

    public UnityDependencyResolver(IUnityContainer container) {
      _container = container;
    }

    public object GetService(Type serviceType) {
      if (typeof(IController).IsAssignableFrom(serviceType)) {
        return ChildContainer.Resolve(serviceType);
      }
      return IsRegistered(serviceType) ? ChildContainer.Resolve(serviceType) : null;
    }

    public IEnumerable<object> GetServices(Type serviceType) {
      if (IsRegistered(serviceType)) {
        yield return ChildContainer.Resolve(serviceType);
      }
      foreach (var service in ChildContainer.ResolveAll(serviceType)) {
        yield return service;
      }
    }

    protected IUnityContainer ChildContainer {
      get {
        var childContainer = HttpContext.Current.Items[HttpContextKey] as IUnityContainer;
        if (childContainer == null) {
          HttpContext.Current.Items[HttpContextKey] = childContainer = _container.CreateChildContainer();
        }
        return childContainer;
      }
    }

    public static void DisposeOfChildContainer() {
      var childContainer = HttpContext.Current.Items[HttpContextKey] as IUnityContainer;
      if (childContainer != null) childContainer.Dispose();
    }

    private bool IsRegistered(Type typeToCheck) {
      var isRegistered = true;
      if (typeToCheck.IsInterface || typeToCheck.IsAbstract) {
        isRegistered = ChildContainer.IsRegistered(typeToCheck);
        if (!isRegistered && typeToCheck.IsGenericType) {
          var openGenericType = typeToCheck.GetGenericTypeDefinition();
          isRegistered = ChildContainer.IsRegistered(openGenericType);
        }
      }
      return isRegistered;
    }
  }
}

Global.asax 啟動註冊

在 Application_Start 中建立容器、註冊類型並設定 Dependency Resolver：

using System.Web.Mvc;
using System.Web.Optimization;
using System.Web.Routing;
using App.Core;
using Microsoft.Practices.Unity;

namespace App.Admin {
  public class MvcApplication : System.Web.HttpApplication {
    protected void Application_Start() {
      AreaRegistration.RegisterAllAreas();
      // ... 其他初始化 ...
      var container = new UnityContainer();
      DependencyRegisterType.Container_Sys(ref container);
      DependencyResolver.SetResolver(new UnityDependencyResolver(container));
    }
  }
}

原始碼下載

完整專案原始碼可至：Microsoft.Practices.Unity.rar