在Global.asax中注入依赖项

Question

我正在使用MVC3和Ninject启动Web应用程序.在Global.asax文件中还需要一个依赖项,它需要是一个单例.

我认为应该是这样的:

public class MvcApplication : NinjectHttpApplication
{
    IUserAuthentication _auth;

    public MvcApplication()
    {
        base.AuthenticateRequest += new EventHandler(MvcApplication_AuthenticateRequest);
    }

    protected override IKernel CreateKernel()
    {
        var _kernel = new StandardKernel(new SecurityModule());
        _auth = _kernel.Get<IUserAuthentication>();

        return _kernel;
    }

    void MvcApplication_AuthenticateRequest(object sender, EventArgs e)
    {
        _auth.ToString();
    }

但后来我看到它被调用_auth时MvcApplication_AuthenticateRequest为null .

然后我试着这样:

public class MvcApplication : NinjectHttpApplication
{
    ItUserAuthentication _auth;
    IKernel _kernel;

    public MvcApplication()
    {
        _kernel = new StandardKernel(new SecurityModule());
        _auth = _kernel.Get<IUserAuthentication>();
        base.AuthenticateRequest += new EventHandler(MvcApplication_AuthenticateRequest);
    }

    protected override IKernel CreateKernel()
    {
        return _kernel;
    }

    void MvcApplication_AuthenticateRequest(object sender, EventArgs e)
    {
        _auth.ToString();
    }

但现在我可以看到构造函数被多次调用,因此我将有几个IKernel,我想单例实例在我的应用程序范围内不会是单例.

我该怎么办？使用静态变量？

Answer 1

我们就是这样做的,我做了一些测试,我的AuthService似乎只进入他的控制器一次:

public class MvcApplication : NinjectHttpApplication
    {

        public static void RegisterRoutes(RouteCollection routes)
        {
            routes.IgnoreRoute("{resource}.axd/{*pathInfo}");

            routes.MapRoute(
                "Default", // Route name
                "{controller}/{action}/{id}", // URL with parameters
                new { controller = "Home", action = "Index", id = UrlParameter.Optional } // Parameter defaults
            );

        }

        protected override IKernel CreateKernel()
        {
            var kernel = new StandardKernel();
            kernel.Load(Assembly.GetExecutingAssembly());

            kernel.Bind<ISession>().To<MongoSession>().InRequestScope();
            kernel.Bind<IAuthenticationService>().To<AuthenticationService>().InSingletonScope();
            kernel.Bind<IMailer>().To<Mailer>().InRequestScope();
            kernel.Bind<IFileProvider>().To<MongoFileProvider>().InRequestScope();

            return kernel;
        }

        protected override void OnApplicationStarted()
        {
            base.OnApplicationStarted();

            AreaRegistration.RegisterAllAreas();
            RegisterRoutes(RouteTable.Routes);
        }

        protected void Application_AuthenticateRequest(Object sender, EventArgs e)
        {
            if (HttpContext.Current.User != null)
            {
                if (HttpContext.Current.User.Identity.IsAuthenticated)
                {
                    if (HttpContext.Current.User.Identity is FormsIdentity)
                    {
                        var id = (FormsIdentity) HttpContext.Current.User.Identity;
                        var ticket = id.Ticket;
                        var authToken = ticket.UserData;
                        var authService = (IAuthenticationService)DependencyResolver.Current.GetService(typeof(IAuthenticationService));
                        var user = authService.GetUserForAuthToken(authToken);
                        if (user != null)
                        {
                            user.SetIdentity(HttpContext.Current.User.Identity);
                            HttpContext.Current.User = (IPrincipal) user;
                        }
                    }
                }
            }
        }
}

希望能帮助到你!

Answer 2

MVC扩展默认注入HttpApplication.但只能使用属性注入!所以只需添加一个用Inject属性修饰的属性.