Unity框架，是一個經典的IoC模式實現方式，其通過config文件配置section，將接口與實現解藕，config中的section配置的container以全名稱對應，使得應用程序無需像Ninject方式那樣，依賴接口項和實現項，因其解藕的配置，能讓應用程序實現靜態更新服務的效果，即不退出應用程序更新服務的功能。

下面是Unity的實現，其核心接口IUnityContainer是Unity模式實現的基礎，在Controller生命周期中IUnityContainer起到傳遞section配置的作用，在Controller實例化時創建依賴的接口服務的實例對象，當Countroller執行結束後，接口服務的實例對象交由IUnityContainer維護

首先需要安裝Unity，引用以下兩個dll

接下來實現Unity的管理類，新建mvc5網站項目，並如下實現

public class UnityControllerFactory : DefaultControllerFactory
    {
        static object syncHelper = new object();
        static Dictionary<string, IUnityContainer> containers = new Dictionary<string, IUnityContainer>();
        
 
public IUnityContainer UnityContainer { get; private set; }
        public UnityControllerFactory(string containerName = "")
        {
            if (containers.ContainsKey(containerName))
            {
                this.UnityContainer = containers[containerName];
                return;
            }
            
 
lock (syncHelper)
            {
                if (containers.ContainsKey(containerName))
                {
                    this.UnityContainer = containers[containerName];
                    return;
                }
                IUnityContainer container = new UnityContainer();
                //配置UnityContainer
                UnityConfigurationSection configSection = ConfigurationManager.GetSection(UnityConfigurationSection.SectionName) as UnityConfigurationSection;
                if (null == configSection && !string.IsNullOrEmpty(containerName))
                {
                    throw new ConfigurationErrorsException("The <unity> configuration section does not exist.");
                }
                if (null != configSection)
                {
                    if (string.IsNullOrEmpty(containerName))
                    {
                        configSection.Configure(container);
                    }
                    else
                    {
                        configSection.Configure(container, containerName);
                    }
                }
                containers.Add(containerName, container);
                this.UnityContainer = containers[containerName];
            }
        }
        protected override IController GetControllerInstance(RequestContext requestContext, Type controllerType)
        {
            if (null == controllerType)
            {
                return null;
            }
            return (IController)this.UnityContainer.Resolve(controllerType);
        }
        public override void ReleaseController(IController controller)
        {
            this.UnityContainer.Teardown(controller);
        }
    }

假設有一個服務接口在一個獨立的C#類庫名為MyInterface

public interface IEmployeeRepository
    {
        IEnumerable<Employee> GetEmployees(string id = "");
    }

和服務接口的實現項在一個獨立的C#類庫名為MyService

public class EmployeeRepository: IEmployeeRepository
    {
        private static IList<Employee> employees;
        static EmployeeRepository()
        {
            employees = new List<Employee>();
            employees.Add(new Employee(Guid.NewGuid().ToString(), "張三", "男", new DateTime(1981, 8, 24), "銷售部"));
            employees.Add(new Employee(Guid.NewGuid().ToString(), "李四", "女", new DateTime(1982, 7, 10), "人事部"));
            employees.Add(new Employee(Guid.NewGuid().ToString(), "王五", "男", new DateTime(1981, 9, 21), "人事部"));
        }
        public IEnumerable<Employee> GetEmployees(string id = "")
        {
            return employees.Where(e => e.Id == id || string.IsNullOrEmpty(id) || id == "*");
        }
    }

在上面新建的mvc5網站項目中，引用MyInterface的C#類庫，在網站的global文件中Application_Start中添加如下這句，將我們創建的UnityControllerFactory註入給ControllerBuilder初始化

ControllerBuilder.Current.SetControllerFactory(new UnityControllerFactory());

在mvc5網站的web.config中添加section接口服務map信息，將接口與其服務實現類信息配置給Unity

<unity>
    <containers>
      <container>
        <register type="Mvc.IEmployeeRepository, Mvc.MvcApp" 
                  mapTo="Mvc.EmployeeRepository, Mvc.MvcApp"/>
      </container>
    </containers>
  </unity>

Unity與於Ninject的好處很明顯，接口與實現解藕，無需直接依賴實現項，達到靜態更新的效果，在應用程序運行時，只需將實現項的DLL(此處即為MyService.dll)下載替換，即可實現服務更新，要實現自動化靜態更新當然需要做些工作，比如MyService應該需要版本檢測及下載功能，有興趣的可以做做

Unity IoC Base On MVC