解决Autofac MVC 自动注入在 Areas拆分到不同dll下的注入失败问题

由于项目业务复杂，创建了多个Areas 并把他们放在了不同的项目中，项目使用AutoFac做的IOC

配置代码为

  public class MvcApplication : System.Web.HttpApplication
     {
         protected void Application_Start()
         {
             //依赖注入
             var builder = new ContainerBuilder();
             builder.RegisterModule(new ConfigurationSettingsReader("autofac"));
             builder.RegisterControllers(Assembly.GetExecutingAssembly());

             var container = builder.Build();
             DependencyResolver.SetResolver(new AutofacDependencyResolver(container));

             AreaRegistration.RegisterAllAreas();
                 WebApiConfig.Register(GlobalConfiguration.Configuration);
             FilterConfig.RegisterGlobalFilters(GlobalFilters.Filters);
             RouteConfig.RegisterRoutes(RouteTable.Routes);
         }
     }

在 Controllers中 采用 构造函数来实现注入

namespace xxx.Web.Person.Controllers
{
    /// <summary>
    /// 定位模块
    /// </summary>
    public class LocationController : Controller
    {
        private ILocationService _location;
        public LocationController(ILocationService location)
        {
            _location = location;
        }
    }
}

启动后报错 错误信息：

[MissingMethodException: 没有为该对象定义无参数的构造函数。]
   System.RuntimeTypeHandle.CreateInstance(RuntimeType type, Boolean publicOnly, Boolean noCheck, Boolean& canBeCached, RuntimeMethodHandleInternal& ctor, Boolean& bNeedSecurityCheck) +0
   System.RuntimeType.CreateInstanceSlow(Boolean publicOnly, Boolean skipCheckThis, Boolean fillCache) +98
   System.RuntimeType.CreateInstanceDefaultCtor(Boolean publicOnly, Boolean skipVisibilityChecks, Boolean skipCheckThis, Boolean fillCache) +241
   System.Activator.CreateInstance(Type type, Boolean nonPublic) +69
   System.Web.Mvc.DefaultControllerActivator.Create(RequestContext requestContext, Type controllerType) +67

[InvalidOperationException: 尝试创建“xxx.Web.Person.Controllers.HomeController”类型的控制器时出错。请确保控制器具有无参数公共构造函数。]

通过错误信息得知 AutoFac 的RegisterControllers 只是 注入了xxx.Web的 Controllers 对于引用的 xxx.web.Person.dll 下的 Controller 没有注入。
解决方法如下：

 public class MvcApplication : System.Web.HttpApplication
    {
        protected void Application_Start()
        {
            //依赖注入
            var builder = new ContainerBuilder();
            builder.RegisterModule(new ConfigurationSettingsReader("autofac"));
            builder.RegisterControllers(Assembly.GetExecutingAssembly());

            //解决Areas在不同的Dll中注入问题
            var assemblies = new DirectoryInfo(
                      HttpContext.Current.Server.MapPath("~/bin/"))
                .GetFiles("*.dll")
                .Select(r => Assembly.LoadFrom(r.FullName)).ToArray();
            builder.RegisterAssemblyTypes(assemblies)
                .Where(r => r.BaseType == typeof(Controller))
                .InstancePerHttpRequest();

            var container = builder.Build();
            DependencyResolver.SetResolver(new AutofacDependencyResolver(container));

            AreaRegistration.RegisterAllAreas();
            WebApiConfig.Register(GlobalConfiguration.Configuration);
            FilterConfig.RegisterGlobalFilters(GlobalFilters.Filters);
            RouteConfig.RegisterRoutes(RouteTable.Routes);
        }
    }

　　重新编译  运行正常。