.Net Web Api 2.2终结点中的依赖项注入不可用

Question

我有一个控制台应用程序，它的工作原理像网络api一样退出。我在Program.cs上注册

var collection = new ServiceCollection();
collection.AddScoped<IInfoBusinessComponent, InfoBusinessComponent>();

在添加InfoBusinessComponent之前，InfoBusinessComponent还需要进行依赖项注入。我也注册我的ILogger。

在我的InfoController上，我像这样使用di：

public InfoController(IInfoBusinessComponent businessComponent, ILogger<InfoController> logger)

当我现在呼叫该端点时，我立即收到500响应。当我从控制器中删除参数时，该过程将进入构造函数和控制器。但这不是我想要的。

    public InfoController()

为什么构造函数没有得到依赖注入或为什么没有调用构造函数？

public class Program
{
    #region fields and propetries
    public IConfiguration Configuration { get; }  
    //# if DEBUG
    //#endif
    public static IConnection Connection { get; set; }
    public static ITimeSeriesBusinessComponent TimeSeriesBusinessComponent { get; set; }
    public static IInfoBusinessComponent InfoBusinessComponent { get; set; }
    private static int counter;
    #endregion fields and propetries

    public static void Main(string[] args)
    {
        IConfiguration config = GetConfigurations();
        ILogger logger = GetLogger();
        ServiceProvider appServiceProvider = GetServiceProvider(config);

        Parallel.Invoke
        (
            () =>
            {
                BuildWebHost(args).Build().Run();
            }, 
            () =>
            {
                //...
            }
        );


    }

    private static IConfiguration GetConfigurations()
    {
        var builder = new ConfigurationBuilder()
                        .SetBasePath(Directory.GetCurrentDirectory())
                        .AddJsonFile("appsettings.json");

        IConfiguration config = new ConfigurationBuilder()
            .AddJsonFile("appsettings.json", true, true)
            .Build();
        return config;
    }

    private static ILogger GetLogger()
    {
        ILogger logger = new LoggerFactory().AddNLog().CreateLogger<Program>();
        return logger;
    }

    private static ServiceProvider GetServiceProvider(IConfiguration config)
    {
        var collection = new ServiceCollection();
        collection.AddLogging(configuration => configuration.AddNLog());
        //...
        collection.AddScoped<IInfoRepository>(serviceProvider =>
        {
            return new InfoRepository(
                config["ConnectionStrings:MainConnection"], 
                config["ConnectionStrings:MetaDataConnection"],
                config["InfoFunctionName"],
                config["UserName"],
                config["Password"],
                config["VirtualHost"],
                config["ConnectionHostName"]);
        });
        collection.AddScoped<IInfoBusinessComponent, InfoBusinessComponent>();
        var appServiceProvider = collection.BuildServiceProvider();
        return appServiceProvider;
    }

    public static IWebHostBuilder BuildWebHost(string[] args) =>
        WebHost.CreateDefaultBuilder(args)
            .UseStartup<Startup>()
            .UseApplicationInsights()
            .UseUrls("http://0.0.0.0:5003")
            .UseNLog();
}

这里是Startup.cs：

public class Startup
{
    public IConfiguration Configuration { get; }

    public Startup(IConfiguration configuration)
    {
        Configuration = configuration;
    }

    public void ConfigureServices(IServiceCollection services)
    {
        services.AddSwaggerGen(c =>
        {
            c.SwaggerDoc("v1", new Info
            {
                Title = "My CLI"
            });
        });
        services.AddMvc();
    }

    public void Configure(IApplicationBuilder app, IHostingEnvironment env)
    {
        app.UseSwagger();
        app.UseSwaggerUI(c =>
        {
            c.SwaggerEndpoint("/swagger/v1/swagger.json", "My CLI");
            c.DocExpansion(Swashbuckle.AspNetCore.SwaggerUI.DocExpansion.None);
            c.RoutePrefix = string.Empty;
        });

        app.UseMvc();
    }
}

Answer 1

问题是您创建的端点BuildWebHost使用自己的实例ServiceProvider。ServiceProvider您创建的实例不会进入管道。

原因： ServiceCollection不使用任何类型的单例注册表，因此仅通过的某个实例注册服务ServiceCollection并构建的某个实例还不够ServiceProvider。您必须使端点使用ServiceCollection/ 的特定实例ServiceProvider。或者，您可以将您的文件复制ServiceCollection到端点使用的文件中-这就是我要解决的方法。

因此，让我们使用a ServiceCollection来注册您的服务（现在为止）。然后，而不是做collection.BuildServiceProvider()，我们使用的是ServiceCollection在Startup向所有注册复制到由管道使用的服务集合。

首先，让我们公开您的ServiceCollection访问权限Startup：

class Program
{
    public static ServiceCollection AppServices { get; set; }

    public static void Main(string[] args)
    {
        // ...other stuff...

        AppServices = GetServiceCollection(config);

        // ...other stuff...
    }

    // renamed from GetServiceProvider
    private static ServiceCollection GetServiceCollection(IConfiguration config)
    {
        var collection = new ServiceCollection();

        // ... register services...

        return collection;
    }
}

然后在Startup类中，使用Program.AppServices中ConfigureServices()，如下所示：

编辑：注意usingStartup.cs中的s

// make sure these usings are present:
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.DependencyInjection.Extensions;

....

public class Startup
{
    // ... other members ...

    public void ConfigureServices(IServiceCollection services)
    {
        // ... the usual stuff like services.AddMvc()...

        // add this line:
        services.TryAdd(Program.AppServices);
    }

    // ... other members ...
}