在 MVC 控制器中使用 构造函数时行依赖注入 （IoC)

 在 Controller 中使用 构造函数进行依赖注入 (IoC)

1. Controller 代码：

  ICard card;
        ICardCategory cardCategory;
        public CardController(ICard card, ICardCategory cardCategory)
        {
            this.card = card;
            this.cardCategory = cardCategory;
        }

 接口 ICard , ICardCateogry 是一个普通的接口，没有继承或实现任何接口，而需要做的就是在 Gloable.cs 文件中解析依赖， 为了方便复用，将解析依赖封装成一个类，然后在 Gloable.cs 文件中注册，在这个示例中，使用的是 Unity 进行依赖注入，完整的代码如下：

using Microsoft.Practices.Unity;
using System;
using System.Collections.Generic;
//using System.Web.Http.Dependencies;
using System.Web;
using System.Web.Mvc;

namespace SnsManage.Resolver
{
   /// <summary>
   ///  Dependency Injection  Resolver Container 
   /// </summary>
    public class UnityResolver : IDependencyResolver
    {
        protected IUnityContainer container;

        public UnityResolver(IUnityContainer container)
        {
            if (container == null)
            {
                throw new ArgumentNullException("container");
            }
            this.container = container;
        }

        public object GetService(Type serviceType)
        {
            try
            {
                return container.Resolve(serviceType);
            }
            catch (ResolutionFailedException)
            {
                return null;
            }
        }

        public IEnumerable<object> GetServices(Type serviceType)
        {
            try
            {
                return container.ResolveAll(serviceType);
            }
            catch (ResolutionFailedException)
            {
                return new List<object>();
            }
        }

        //public IDependencyScope BeginScope()
        //{
        //    var child = container.CreateChildContainer();
        //    return new UnityResolver(child);
        //}

        //public void Dispose()
        //{
        //    container.Dispose();
        //}




        //private const string HttpContextKey = "perRequestContainer";

        //private readonly IUnityContainer container;

        //public UnityResolver(IUnityContainer container)
        //{
        //    this.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;
        //}
    }
}

然后在 App_Start 文件中添加一个配置类， UnityConfig.cs, 其中的代码如下：

    public static class UnityConfig
    {
       /// <summary>
       ///  Dependency Injection 
       /// </summary>
        public static void RegisterComponents()
        {
            var container = new UnityContainer();
            
            // register all your components with the container here
            // it is NOT necessary to register your controllers
            
            // e.g. container.RegisterType<ITestService, TestService>();
            
            container.RegisterType<IUser, UserService>( new HierarchicalLifetimeManager());

            DependencyResolver.SetResolver(new UnityResolver(container));
            
        }
    }

最后在 Global.asax 文件中注册

            UnityConfig.RegisterComponents();