Asp.net MVC 通過自定義ControllerFactory實現構造器注入

一、重寫ControllerFactory的GetControllerInstance

ControllerFactory是asp.net中用於在運行時構造Controller的工廠 ，默認使用的工廠在構造Controller時，默認調用Controller的無參構造函數，所以要實現構造器注入，需要重寫工廠中構造Controller的方法GetControllerInstance：

public class CustomControllerFactory : DefaultControllerFactory
    {
        protected override IController GetControllerInstance(System.Web.Routing.RequestContext requestContext,Type controllerType)
        {
            //獲取構造函數對象
            var constructor = controllerType.GetConstructors()[0];
            //獲取構造函數參數
            var param = constructor.GetParameters();
            //獲取構造函數所需的參數
            var paramNames = param.Select(a => {
                var serviceType = (ServiceAttribute)(a.ParameterType.GetCustomAttributes(typeof(ServiceAttribute), true)[0]);
                var t = Type.GetType(serviceType.ServiceName + ", " + serviceType.ServiceNameSpace, true);
                return Activator.CreateInstance(t);
                }).ToArray();
            IController controller = Activator.CreateInstance(controllerType, paramNames) as Controller;
            return controller;
        }
    }

 

在獲取構造函數參數的時候，需要讓發射機制尋找到服務的程序集，所以在這個地方我定義了一個名為Service的特性：

public class ServiceAttribute : Attribute
    {
        private string _serviceName;
        private string _serviceNamespace;
        public ServiceAttribute(string serviceName, string serviceNamespace)
        {
            _serviceName = serviceName;
            _serviceNamespace = serviceNamespace;
        }

        public string ServiceName
        {
            get { return _serviceName; }
        }

        public string ServiceNameSpace
        {
            get { return _serviceNamespace; }
        }
    }

 

二、定義服務接口：

[Service(serviceName: "InjectController.Service.Impl.AddService", serviceNamespace: "InjectController.Service.Impl")]
public interface IAddService
{
    int Add(int a, int b);
}

 

serviceName是服務的全稱，serviceNamespace是服務的命名空間。

三、繼承服務接口並實現：

    public class AddService:IAddService
    {
        public int Add(int a, int b)
        {
            return a + b;
        }
    }

 

四、在Controller中定義構造函數，引用服務接口

    public class HomeController : Controller
    {
        private ILoggerService _loggerService;
        private IAddService _addService;
        public HomeController(ILoggerService loggerService,IAddService addService)
        {
            _loggerService = loggerService;
            _addService = addService;
        }

        public ActionResult Index(int num1, int num2)
        {
            _loggerService.Logger(num1.ToString() + "+" + num2.ToString() + "=" + _addService.Add(num1,num2).ToString() + "    " + "\r\n");
            return View("Index", new LoggerDTO() { LoggerContent = _loggerService.GetLogger() });
        }
    }

 

ILoggerService沒有在文章中列出，其格式與IAddService相同。

五、在Global.asax中重新注冊控制器工廠，覆蓋默認的構造器工廠：

    public class MvcApplication : System.Web.HttpApplication
    {
        protected void Application_Start()
        {
            AreaRegistration.RegisterAllAreas();
            FilterConfig.RegisterGlobalFilters(GlobalFilters.Filters);
            RouteConfig.RegisterRoutes(RouteTable.Routes);
            BundleConfig.RegisterBundles(BundleTable.Bundles);

            RegisterCustomControllerFactory();
        }

        private void RegisterCustomControllerFactory()
        {
            IControllerFactory factory = new CustomControllerFactory();
            ControllerBuilder.Current.SetControllerFactory(factory);
        }
    }

 

運行：發現接口成功的在構造函數中被注入