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：
protected internal virtual IController GetControllerInstance(RequestContext requestContext, Type controllerType)
{
if (controllerType == null)
{
throw new HttpException(,
String.Format(
CultureInfo.CurrentCulture,
MvcResources.DefaultControllerFactory_NoControllerFound,
requestContext.HttpContext.Request.Path));
}
if (!typeof(IController).IsAssignableFrom(controllerType))
{
throw new ArgumentException(
String.Format(
CultureInfo.CurrentCulture,
MvcResources.DefaultControllerFactory_TypeDoesNotSubclassControllerBase,
controllerType),
"controllerType");
}
return ControllerActivator.Create(requestContext, controllerType);
}
重写后：
public class DefaultFactoryIOC:DefaultControllerFactory
{
private IKernel kernel;
public DefaultFactoryIOC()
{
kernel = new StandardKernel();
kernel.Bind<IRespo>().To<Respo>();
}
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<IRespo>().To<Respo>();
}
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<IDependencyResolver> _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<IRespo>().To<Respo>();
}
public object GetService(Type serviceType)
{
var obj = this.kernel.TryGet(serviceType);
return obj;
} public IEnumerable<object> GetServices(Type serviceType)
{
return this.kernel.GetAll(serviceType);
}
}
// 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);
}
}