c# - ASP.NET 核心。配置DI为不同的接口(interface)获取相同的对象

Question

我有中间件，它可以完成一些工作并创建对象。我需要将此对象注入(inject)到 Controller 中。 到目前为止，我看到了具有额外层的解决方案，通过向 DI 添加一些工厂，该工厂通过从 context.Items['myobject_created_and_placed_here_in_middleware'] 中提取已创建的对象来创建此类对象。

我也在考虑另一种方式:

public interface IReader
{
    string Get();
}

public interface IWriter
{
    string Set(string value);
}

public class Object1 : IReader, IWriter
{
    public string s1 { get; set; }
    public string Get()
    {
        return this.s1;
    }

    public string Set(string value)
    {
        this.s1 = value;
        return s1;
    }
}

public class Middleware1
{
    RequestDelegate next;
    private readonly IReader _reader;


    public Middleware1(RequestDelegate next, IReader reader)
    {
        this.next = next;
        _reader = reader;
    }

    public async Task Invoke(HttpContext context)
    {
        var test1 = _reader.Get();
        await next.Invoke(context);
    }
}

public class Middleware2
{
    RequestDelegate next;
    private readonly IWriter _writer;


    public Middleware2(RequestDelegate next, IWriter writer)
    {
        this.next = next;
        _writer = writer;
    }

    public async Task Invoke(HttpContext context)
    {
        _writer.Set("13168AAE-C886-453E-B655-ECE5D14645D9");
        await next.Invoke(context);
    }
}

启动.cs:

    public void Configure(IApplicationBuilder app, IHostingEnvironment env, ILoggerFactory loggerFactory)
    {
        loggerFactory.AddConsole();

        app.UseMiddleware<Middleware2>();
        app.UseMiddleware<Middleware1>();

        app.Run(async (context) =>
        {
            await context.Response.WriteAsync("Hello World!");
        });
    }

到目前为止还不起作用。
这将返回不同的对象:

services.AddScoped<IReader,Object1>();
services.AddScoped<IWriter, Object1>();

这无法解析接口(interface):

services.AddScoped<Object1>();

问题是:如何在 DI 中注册它并为每个请求的不同接口(interface)获取相同的对象。

Answer 1

仅供引用:可以在 DI 注册之间共享单个对象，甚至在 Scoped 和 Transient 注册之间也是如此。如果可能的话尽量避免。

public interface IGodObject { } //empty marker interface
public interface IWriter { }
public interface IReader { }
public class GodObject : IGodObject, IReader, IWriter { }

services.AddScoped<IGodObject>(p =>
{
    return new GodObject();
});

services.AddScoped<IReader>(p =>
{
    return p.GetService<IGodObject>() as IReader;
});

services.AddScoped<IWriter>(p =>
{
    return p.GetService<IGodObject>() as IWriter;
});