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

浏览数：22 / 时间：2015年06月09日

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

 1  public class MvcApplication : System.Web.HttpApplication
 2     {
 3         protected void Application_Start()
 4         {
 5             //依赖注入
 6             var builder = new ContainerBuilder();
 7             builder.RegisterModule(new ConfigurationSettingsReader("autofac"));
 8             builder.RegisterControllers(Assembly.GetExecutingAssembly());
 9 
10             var container = builder.Build();
11             DependencyResolver.SetResolver(new AutofacDependencyResolver(container));
12 
13             AreaRegistration.RegisterAllAreas();
14                 WebApiConfig.Register(GlobalConfiguration.Configuration);
15             FilterConfig.RegisterGlobalFilters(GlobalFilters.Filters);
16             RouteConfig.RegisterRoutes(RouteTable.Routes);
17         }
18     }

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);
       }
   }