我在使用 Ninject 的 InSingletonScope 与 Web Api RC 绑定时遇到了一些困难。无论我如何创建绑定，看起来 Web Api 可能正在处理范围/生命周期而不是 Ninject。
我尝试了一些关于连接 Ninject 的变体。最常见的与此处的答案相同： ASP.NET Web API binding with ninject
我也试过这个版本： http ://www.peterprovost.org/blog/2012/06/19/adding-ninject-to-web-api/
在这两者中，我实际上是在创建一个开箱即用的 Web Api 项目，然后按照任一帖子中的描述添加 Ninject 包。最后，我添加了 Resolver 和 Scope 类，例如 StackOverflow 版本：
public class NinjectDependencyScope : IDependencyScope
{
private IResolutionRoot resolver;
internal NinjectDependencyScope(IResolutionRoot resolver)
{
Contract.Assert(resolver != null);
this.resolver = resolver;
}
public void Dispose()
{
IDisposable disposable = resolver as IDisposable;
if (disposable != null)
disposable.Dispose();
resolver = null;
}
public object GetService(Type serviceType)
{
if (resolver == null)
throw new ObjectDisposedException("this", "This scope has already been disposed");
return resolver.TryGet(serviceType);
}
public IEnumerable<object> GetServices(Type serviceType)
{
if (resolver == null)
throw new ObjectDisposedException("this", "This scope has already been disposed");
return resolver.GetAll(serviceType);
}
}
和：
public class NinjectDependencyResolver : NinjectDependencyScope, IDependencyResolver
{
private IKernel kernel;
public NinjectDependencyResolver(IKernel kernel)
: base(kernel)
{
this.kernel = kernel;
}
public IDependencyScope BeginScope()
{
return new NinjectDependencyScope(kernel.BeginBlock());
}
}
然后，NinjectWebCommon 看起来像这样：
using System.Web.Http;
using MvcApplication2.Controllers;
[assembly: WebActivator.PreApplicationStartMethod(typeof(MvcApplication2.App_Start.NinjectWebCommon), "Start")]
[assembly: WebActivator.ApplicationShutdownMethodAttribute(typeof(MvcApplication2.App_Start.NinjectWebCommon), "Stop")]
namespace MvcApplication2.App_Start
{
using System;
using System.Web;
using Microsoft.Web.Infrastructure.DynamicModuleHelper;
using Ninject;
using Ninject.Web.Common;
public static class NinjectWebCommon
{
private static readonly Bootstrapper bootstrapper = new Bootstrapper();
/// <summary>
/// Starts the application
/// </summary>
public static void Start()
{
DynamicModuleUtility.RegisterModule(typeof(OnePerRequestHttpModule));
DynamicModuleUtility.RegisterModule(typeof(NinjectHttpModule));
bootstrapper.Initialize(CreateKernel);
}
/// <summary>
/// Stops the application.
/// </summary>
public static void Stop()
{
bootstrapper.ShutDown();
}
/// <summary>
/// Creates the kernel that will manage your application.
/// </summary>
/// <returns>The created kernel.</returns>
private static IKernel CreateKernel()
{
var kernel = new StandardKernel();
kernel.Bind<Func<IKernel>>().ToMethod(ctx => () => new Bootstrapper().Kernel);
kernel.Bind<IHttpModule>().To<HttpApplicationInitializationHttpModule>();
// Register Dependencies
RegisterServices(kernel);
// Set Web API Resolver
GlobalConfiguration.Configuration.DependencyResolver = new NinjectDependencyResolver(kernel);
return kernel;
}
/// <summary>
/// Load your modules or register your services here!
/// </summary>
/// <param name="kernel">The kernel.</param>
private static void RegisterServices(IKernel kernel)
{
kernel.Bind<ILogger>().To<Logger>().InSingletonScope();
}
}
}
ILogger 和 Logger 对象不做任何事情，但可以说明问题。Logger 执行 Debug.Writeline 以便我可以看到它何时被实例化。页面的每次刷新都表明每次调用都会刷新它，而不是我希望的单例。这是一个使用 Logger 的控制器：
public class ValuesController : ApiController
{
private readonly ILogger _logger;
public ValuesController(ILogger logger)
{
_logger = logger;
_logger.Log("Logger created at " + System.DateTime.Now.ToLongTimeString());
}
// GET api/values
public IEnumerable<string> Get()
{
return new string[] { "value1", "value2" };
}
// GET api/values/5
public string Get(int id)
{
return "value";
}
// POST api/values
public void Post(string value)
{
}
// PUT api/values/5
public void Put(int id, string value)
{
}
// DELETE api/values/5
public void Delete(int id)
{
}
}
当我将跟踪信息放入内核的创建中时，似乎表明内核只创建了一次。所以……我没看到什么？为什么不坚持单例？