Ninject equivalent to MEF AssemblyCatalog

本文关键字：AssemblyCatalog MEF to equivalent Ninject | 更新日期: 2023-09-27 18:34:50

在 MEF 中，AssemblyCatalog用于扫描程序集以查找所有导出的类型并配置容器。有与Ninject等价物吗？

var catalog = new AggregateCatalog();
catalog.Catalogs.Add(new AssemblyCatalog(Assembly.GetExecutingAssembly()));
var container = new CompositionContainer(catalog);

Ninject equivalent to MEF AssemblyCatalog

在 Ninject 中，使用类型和扫描程序集的属性来添加绑定的功能由名为 Ninject.Extensions.Convention 的扩展提供。

  1. 添加约定包，例如使用包管理器控制台：

    Install-Package Ninject.Extensions.Conventions

  2. 创建一些要在服务上使用的自定义属性。这将等效于 MEF 中的ExportAttribute：

    public enum ExportScope
{
    Singleton,
    Transient
}
[AttributeUsage(AttributeTargets.Class)]
public class ExportAttribute : Attribute
{
    public ExportAttribute(Type serviceInterface, ExportScope scope = ExportScope.Singleton)
    {
        this.ServiceInterface = serviceInterface;
        this.Scope = scope;
    }
    public Type ServiceInterface { get; set; }
    public ExportScope Scope { get; set; }
}

  3. 创建一个自定义 BindingGenerator，它使用我们的ExportAttribute将类型绑定到给定接口：

    public class ExportAttributeBindingGenerator : IBindingGenerator
{
    public IEnumerable<IBindingWhenInNamedWithOrOnSyntax<object>> CreateBindings(Type type, IBindingRoot bindingRoot)
    {
        var attribute = type.GetCustomAttribute<ExportAttribute>();
        var serviceType = attribute.ServiceInterface;
        if (!serviceType.IsAssignableFrom(type))
        {
            throw new Exception(string.Format("Error in ExportAttribute: Cannot bind type '{0}' to type '{1}'.", 
                serviceType, type));
        }
        var binding = bindingRoot.Bind(serviceType).To(type);
        switch (attribute.Scope)
        {
            case ExportScope.Singleton:
                yield return (IBindingWhenInNamedWithOrOnSyntax<object>) binding.InSingletonScope();
                break;
            case ExportScope.Transient:
                yield return (IBindingWhenInNamedWithOrOnSyntax<object>) binding.InTransientScope();
                break;
            default:
                throw new ArgumentOutOfRangeException();
        }
    }
}

  4. 创建要在内核上使用的扩展方法并添加约定：

    public static class NinjectBindingExtensions
{
    public static void BindExportsInAssembly(this IBindingRoot root, Assembly assembly)
    {
        root.Bind(c => c.From(assembly)
                          .IncludingNonePublicTypes()
                          .SelectAllClasses()
                          .WithAttribute<ExportAttribute>()
                          .BindWith<ExportAttributeBindingGenerator>());
    }
}

现在，对于如此常见的事情来说，这似乎需要做很多工作，但它非常灵活和可扩展。它做任何你想让它做的事情。把它放在实用程序类库中，并在任何你想要的地方使用它，就像这样：

[Export(typeof(IFoo))]
public class Foo : IFoo
{
}
[Export(typeof(IBar), ExportScope.Transient)]
public class Bar : IBar
{
}
[TestClass]
public class UnitTest1
{
    [TestMethod]
    public void TestNinjectConventions()
    {
        var kernel = new StandardKernel();
        kernel.BindExportsInAssembly(typeof(IFoo).Assembly);
        kernel.Get<IFoo>().Should().Be(kernel.Get<IFoo>());
        kernel.Get<IBar>().Should().NotBe(kernel.Get<IBar>());
    }
}
相关文章：