服务定位器模式和登录用户

Question

I'm adjusting my web application layers in a way to make the code more testable.

Currently the UI talks to a service locator passing in an interface, this returns the appropriate object based on that type:

ServiceLocator.Get<ISomeService>().ListStuff(arg1, arg2);

Internally, services are instantiated with an instance of IServiceContext and cached.

private static Lazy<IDictionary<Type, object>> _services = new Lazy<IDictionary<Type, object>>(GetServices);

public interface IServiceContext
{
    IConfiguration Configuration { get; }

    IUser CurrentUser { get; internal set; }

    ILogProvider Log { get; }

    ICacheProvider Cache { get; }

    IProfilerProvider Profiler { get; }
}

public LogService(IServiceContext serviceContext)
  : base(serviceContext) { }

I'm happy with the concept and it appears to be rugged enough, my only issue is I want to make the current logged in user available in the ServiceContext but unsure the best way to achieve it.

My thoughts travel along these potential options:

1. Keep a simple method in the ServiceLocator that handles getting the users session and injects it into the services as requests for them come in.
2. Move getting the current user out of the IServiceContext and into the ServiceBase base class of each service.
3. Stop doing this and make each service that needs a user dependent on it.

I appreciate any suggestions, I understand this question my not be in the true spirit of the site. I have managed 4 days of trial and error to get to this point, just need the last piece of this puzzle.

Answer 1

There's probably many solutions, and I'm not fully sure I understand your question but I'll try to help anyway.

Whenever I need the current user I make a call to static utility class right in the context of the code that uses it. This way I eliminate the possibility of stale information.

You could make a class that implements IUser like

class User : IUser {
  private System.Security.Principal.WindowsIdentity identity;

  public User() {
    this.identity = identity = System.Security.Principal.WindowsIdentity.GetCurrent();
  }

  public string UserName { get { return this.identity.Name; } }
}

And then maybe:

public class ServiceContext : IServiceContext
{
    IUser CurrentUser { get { return new User(); } }
}