Question

我正在使用MVC4 Web API构建一个Web API，其中包含一个IoC容器（在这种情况下为Simple Injector，但我不认为这个问题与该容器有关）应该暴露各种CRUD和查询操作。在我的案例中使用IOC的原因是我们是一个开发商店，我需要能够让客户构建他们自己的Web API控制器，以暴露他们需要从我们的系统公开需要的数据。因此，我希望设计我的解决方案的方式允许我通过IOC将所有控制器（包括我们的和客户的，外部的和可加载的）控制自己的产品。

该网站没有任何对该库的引用，但该库包含我想在网站中使用的控制器。类型在容器中注册，DependencyResolver设置为自定义依赖项解析程序。我有代码找到DLL插件并加载控制器类型，但当我尝试导航到它将代表它的路线说它找不到它。

即。如果我尝试导航到/ api / Test1Api，我应该看到文本“hello world”

我的问题是，虽然我已经加载了我的控制器类型，但我无法将其转换为网站所说的路线。

我收到错误

未找到与请求URI匹配的HTTP资源

未找到与名为“Test1Api”的控制器匹配的类型。

以下是我如何注册容器

public static class SimpleInjectorInitializer
{
    /// <summary>Initialize the container and register it as MVC3 Dependency Resolver.</summary>
    public static void Initialize()
    {
        //// Did you know the container can diagnose your configuration? Go to: http://bit.ly/YE8OJj.

        // Create the IOC container.
        var container = new Container();

        InitializeContainer(container);

        container.RegisterMvcAttributeFilterProvider();
        // Verify the container configuration
        container.Verify();

        // Register the dependency resolver.
        GlobalConfiguration.Configuration.DependencyResolver =
                    new SimpleInjectorWebApiDependencyResolver(container);
    }

    private static void InitializeContainer(Container container)
    {
        var appPath = AppDomain.CurrentDomain.BaseDirectory;

        string[] files = Directory.GetFiles(appPath + "\\bin\\Plugins", "*.dll",
            SearchOption.AllDirectories);
        var assemblies = files.Select(Assembly.LoadFile);

        // register Web API controllers
        var apiControllerTypes =
            from assembly in assemblies
            where !assembly.IsDynamic
            from type in assembly.GetExportedTypes()
            where typeof(IHttpController).IsAssignableFrom(type)
            where !type.IsAbstract
            where !type.IsGenericTypeDefinition
            where type.Name.EndsWith("Controller", StringComparison.Ordinal)
            select type;

        // register MVC controllers
        var mvcControllerTypes =
            from assembly in assemblies
            where !assembly.IsDynamic
            from type in assembly.GetExportedTypes()
            where typeof(IController).IsAssignableFrom(type)
            where !type.IsAbstract
            where !type.IsGenericTypeDefinition
            where type.Name.EndsWith("Controller", StringComparison.Ordinal)
            select type;

        foreach (var controllerType in apiControllerTypes)
        {
            container.Register(controllerType);
        }

        foreach (var controllerType in mvcControllerTypes)
        {
            container.Register(controllerType);
        }
    }
}

感谢任何帮助。

Answer 1

关于您的解决方案的一个重要警告。将控制器注册到容器中也是非常重要的（这个建议适用于所有DI框架，尽管默认情况下某些框架会强制您注册具体类型）。否则你肯定会被this developer had的同样问题所困扰。

由于IHttpControllerTypeResolver使用IAssembliesResolver，最简单（也是最安全）的解决方案是简单地要求IHttpControllerTypeResolver注册所有控件。在这种情况下，您的SimpleInjectorInitializer将如下所示：

public static class SimpleInjectorInitializer
{
    public static void Initialize()
    {
        // Create the IOC container.
        var container = new Container();

        InitializeContainer(container);

        container.RegisterMvcAttributeFilterProvider();

        // Verify the container configuration
        container.Verify();

        // Register the dependency resolver.
        GlobalConfiguration.Configuration.DependencyResolver =
            new SimpleInjectorWebApiDependencyResolver(container);
    }

    private static void InitializeContainer(Container container)
    {
        GlobalConfiguration.Configuration.Services
            .Replace(typeof(IAssembliesResolver),
                new CustomAssembliesResolver());

        var services = GlobalConfiguration.Configuration.Services;
        var controllerTypes = services.GetHttpControllerTypeResolver()
            .GetControllerTypes(services.GetAssembliesResolver());

        // register Web API controllers (important!)
        foreach (var controllerType in controllerTypes)
        {
            container.Register(controllerType);
        }        
    }
}

另请注意，您的CustomAssembliesResolver可以变得相当容易：

public class CustomAssembliesResolver
    : DefaultAssembliesResolver
{
    private Assembly[] plugins = (
        from file in Directory.GetFiles(
            appPath + "\\bin\\Plugins", "*.dll",
            SearchOption.AllDirectories)
        let assembly = Assembly.LoadFile(file)
        select assembly)
        .ToArray();

    public override ICollection<Assembly> GetAssemblies()
    {
        var appPath =
            AppDomain.CurrentDomain.BaseDirectory;

        return base.GetAssemblies()
            .Union(this.plugins).ToArray();        
    }
}

Answer 2

我明白了！

所以我在Web Api调用CustomAssembliesResolver中创建了一个新类，它继承自DefaultAssembliesResolver。基本上我将我的程序集添加到查找控制器时解析的程序集列表中。我仍然有使用Simple Injector的代码用于解决方案的DI部分。

public class CustomAssembliesResolver : DefaultAssembliesResolver
{
    public override ICollection<Assembly> GetAssemblies()
    {
        var appPath = AppDomain.CurrentDomain.BaseDirectory;
        var baseAssemblies = base.GetAssemblies();
        var assemblies = new List<Assembly>(baseAssemblies);
        var files = Directory.GetFiles(appPath + "\\bin\\Plugins", "*.dll",
                        SearchOption.AllDirectories);
        var customAssemblies = files.Select(Assembly.LoadFile);

        // register Web API controllers
        var apiControllerAssemblies =
            from assembly in customAssemblies
            where !assembly.IsDynamic
            from type in assembly.GetExportedTypes()
            where typeof(IHttpController).IsAssignableFrom(type)
            where !type.IsAbstract
            where !type.IsGenericTypeDefinition
            where type.Name.EndsWith("Controller", StringComparison.Ordinal)
            select assembly;

        foreach (var assembly in apiControllerAssemblies)
        {
            baseAssemblies.Add(assembly);
        }

        return assemblies;
    }
}

我还在Global.asax.cs中将以下行添加到App_Start的开头

GlobalConfiguration.Configuration.Services.Replace(typeof(IAssembliesResolver), new CustomAssembliesResolver());

希望这有助于某人！

非常感谢Steven对他的帮助和见解！我真的很感激!!

无法解析从外部DLL加载的控制器

2 个答案: