[Asp.net 5] DependencyInjection项目代码分析3-Ninject

Microsoft.Framework.DependencyInjection.Ninject

该工程内部共包含5个类文件，底层使用Ninject实现依赖注入，工程截图如下：

从文件命名可以看出，NinjectServiceProvider和NinjectServiceScopeFactory分别是接口IServiceProvider和IServiceScopeFactory的实现类。

（IServiceScope接口的实现类作为NinjectServiceScopeFactory内部类而存在，没有作为单独的文件。）

而工程的入口依旧是Registration为结尾的NinjectRegistration类。

 

NinjectRegistration

文件代码如下

 

 public static class NinjectRegistration
    {
        public static void Populate(this IKernel kernel, IEnumerable<ServiceDescriptor> descriptors)
        {
            kernel.Load(new ServiceProviderNinjectModule(descriptors));
        }

        public static IBindingNamedWithOrOnSyntax<T> InRequestScope<T>(
                this IBindingWhenInNamedWithOrOnSyntax<T> binding)
        {
            return binding.InScope(context => context.Parameters.GetScopeParameter());
        }

        internal static ScopeParameter GetScopeParameter(this IEnumerable<IParameter> parameters)
        {
            return (ScopeParameter)(parameters
                .Where(p => p.Name == typeof(ScopeParameter).FullName)
                .SingleOrDefault());
        }

        internal static IEnumerable<IParameter> AddOrReplaceScopeParameter(
                this IEnumerable<IParameter> parameters,
                ScopeParameter scopeParameter)
        {
            return parameters
                .Where(p => p.Name != typeof(ScopeParameter).FullName)
                .Concat(new[] { scopeParameter });
        }
    }

静态方法：

Populate：作用是将ServiceProviderNinjectModule注册到内核中。对于Ninject大多数时候都会将自定义继承自NinjectModule的类注册到内核中，并且使用该继承类管理依赖注入。

GetScopeParameter：获取所有“ScopeParameter”类型的参数

AddOrReplaceScopeParameter：获取所有“ScopeParameter”参数，并且将它替换成传入的“scopeParameter”。

InRequestScope：在“binding.InScope”中添加“ScopeParameter”。

总体说来，该文件都是些辅助方法，也是对外初始化的接口。

 

ServiceProviderNinjectModule

文件代码如下：

internal class ServiceProviderNinjectModule : NinjectModule
    {
        private readonly IEnumerable<ServiceDescriptor> _serviceDescriptors;

        public ServiceProviderNinjectModule(
                IEnumerable<ServiceDescriptor> serviceDescriptors)
        {
            _serviceDescriptors = serviceDescriptors;
        }

        public override void Load()
        {
            foreach (var descriptor in _serviceDescriptors)
            {
                IBindingWhenInNamedWithOrOnSyntax<object> binding;

                if (descriptor.ImplementationType != null)
                {
                    binding = Bind(descriptor.ServiceType).To(descriptor.ImplementationType);
                }
                else if (descriptor.ImplementationFactory != null)
                {
                    binding = Bind(descriptor.ServiceType).ToMethod(context =>
                    {
                        var serviceProvider = context.Kernel.Get<IServiceProvider>();
                        return descriptor.ImplementationFactory(serviceProvider);
                    });
                }
                else
                {
                    binding = Bind(descriptor.ServiceType).ToConstant(descriptor.ImplementationInstance);
                }

                switch (descriptor.Lifetime)
                {
                    case ServiceLifetime.Singleton:
                        binding.InSingletonScope();
                        break;
                    case ServiceLifetime.Scoped:
                        binding.InRequestScope();
                        break;
                    case ServiceLifetime.Transient:
                        binding.InTransientScope();
                        break;
                }
            }

            Bind<IServiceProvider>().ToMethod(context =>
            {
                var resolver = context.Kernel.Get<IResolutionRoot>();
                var inheritedParams = context.Parameters.Where(p => p.ShouldInherit);

                var scopeParam = new ScopeParameter();
                inheritedParams = inheritedParams.AddOrReplaceScopeParameter(scopeParam);

                return new NinjectServiceProvider(resolver, inheritedParams.ToArray());
            }).InRequestScope();

            Bind<IServiceScopeFactory>().ToMethod(context =>
            {
                return new NinjectServiceScopeFactory(context);
            }).InRequestScope();
        }
    }

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