IOC运用到MVC中-白红宇

IOC运用到MVC中

阅读量：5298 次

发布时间：2019-06-14

本文共 5796 字，大约阅读时间需要 19 分钟。

IOC可以摒弃掉类中类的紧耦合，让设计和重用更简单，将IOC加入到MVC中的实现非常简单，那么有哪几种方法？它们的实现又是什么原理呢？

IOC在MVC中的注入，主要是在获取Controller对象中实现，也就是在获取Controller对象的方法中增加注入的相关实现就可以了，这些入口均是在DefaultControllerFactory类中,目前获取Controller的有如下方法：

（1）重写DefaultControllerFactory中的GetControllerInstance方法

源码：

1   protected internal virtual IController GetControllerInstance(RequestContext requestContext, Type controllerType) 2         { 3             if (controllerType == null) 4             { 5                 throw new HttpException(404, 6                                         String.Format( 7                                             CultureInfo.CurrentCulture, 8                                             MvcResources.DefaultControllerFactory_NoControllerFound, 9                                             requestContext.HttpContext.Request.Path));10             }11             if (!typeof(IController).IsAssignableFrom(controllerType))12             {13                 throw new ArgumentException(14                     String.Format(15                         CultureInfo.CurrentCulture,16                         MvcResources.DefaultControllerFactory_TypeDoesNotSubclassControllerBase,17                         controllerType),18                     "controllerType");19             }20             return ControllerActivator.Create(requestContext, controllerType);21         }

重写后：

public class DefaultFactoryIOC:DefaultControllerFactory    {        private IKernel kernel;        public DefaultFactoryIOC()        {            kernel = new StandardKernel();            kernel.Bind
     
      ().To
      
       ();        }        protected override IController GetControllerInstance(System.Web.Routing.RequestContext requestContext, Type controllerType)        {            return (IController)kernel.TryGet(controllerType);        }    }Global中定义    ControllerBuilder.Current.SetControllerFactory(new IOCTest.DefaultFactoryIOC());

（2）对前面的方法再一次观察发现，实例化Controller最后是交给了ControllerActivator.Create(requestContext, controllerType)方法，也就是如果能够实现或者重写这个方法就能实现注入，那么ControllerActivator来自于

public DefaultControllerFactory(IControllerActivator controllerActivator)            : this(controllerActivator, null, null)        {        }

接下来实现IControllerActivator这个接口，完成第二种IOC方法

public class ControllerActivatorIOC:IControllerActivator    {        private IKernel kernel;        public ControllerActivatorIOC()        {            kernel = new StandardKernel();            kernel.Bind
     
      ().To
      
       ();        }        public IController Create(System.Web.Routing.RequestContext requestContext, Type controllerType)        {            return (IController)kernel.TryGet(controllerType);        }    }Global中  protected void Application_Start()        {            AreaRegistration.RegisterAllAreas();            /*DefaultFactoryController*/            //ControllerBuilder.Current.SetControllerFactory(new IOCTest.DefaultFactoryIOC());            IControllerActivator controlleract = new IOCTest.ControllerActivatorIOC();            DefaultControllerFactory defaultControllerFactory = new DefaultControllerFactory(controlleract);            ControllerBuilder.Current.SetControllerFactory(defaultControllerFactory);        }

（3）接着最后一个方法仍然是从IControllerActivator 中，再DefaultContollerFactory这个Controller激活类中，默认调用实现IControllerActivator的类是DefaultControllerActivator，

它实现了以上这个Create方法

private Func
     
       _resolverThunk; public IController Create(RequestContext requestContext, Type controllerType)            {                try                {                    return (IController)(_resolverThunk().GetService(controllerType) ?? Activator.CreateInstance(controllerType));                }                catch (Exception ex)                {                    throw new InvalidOperationException(                        String.Format(                            CultureInfo.CurrentCulture,                            MvcResources.DefaultControllerFactory_ErrorCreatingController,                            controllerType),                        ex);                }            }

从上可知，Create方法最后会采用那个默认的构造或者第三方实现_resolverThunk的类来实现，而这个_resolverThunk就是从IDependencyResolver接口而来，所以实现IDependencyResolver就可以达到DI的目的

public class DependencyResolverIOC:IDependencyResolver    {        private IKernel kernel;        public DependencyResolverIOC()        {            kernel = new StandardKernel();            kernel.Bind
     
      ().To
      
       ();        }        public object GetService(Type serviceType)        {            var obj = this.kernel.TryGet(serviceType);            return obj;        }        public IEnumerable

// Note: For instructions on enabling IIS6 or IIS7 classic mode,     // visit http://go.microsoft.com/?LinkId=9394801    public class MvcApplication : System.Web.HttpApplication    {        protected void Application_Start()        {            AreaRegistration.RegisterAllAreas();            /*DefaultFactoryController*/            //ControllerBuilder.Current.SetControllerFactory(new IOCTest.DefaultFactoryIOC());            //IControllerActivator controlleract = new IOCTest.ControllerActivatorIOC();            //DefaultControllerFactory defaultControllerFactory = new DefaultControllerFactory(controlleract);            //ControllerBuilder.Current.SetControllerFactory(defaultControllerFactory);            DependencyResolver.SetResolver(new IOCTest.DependencyResolverIOC());            WebApiConfig.Register(GlobalConfiguration.Configuration);            FilterConfig.RegisterGlobalFilters(GlobalFilters.Filters);            RouteConfig.RegisterRoutes(RouteTable.Routes);        }    }

转载于:https://www.cnblogs.com/xiaoweinet/p/3142263.html

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