Autofac 的点滴

泛型类型的注册和使用

public interface IRepository<T> where T:class
{
}

public interface ISchoolDetailRepository : IRepository<SchoolDetail>
{
}

public abstract class RepositoryBase<T> where T : class
{
private LearningCompactPilotContext _dataContext;
private readonly IDbSet<T> _dbset;
protected RepositoryBase(IDatabaseFactory databaseFactory)
{
    DatabaseFactory = databaseFactory;
    _dbset = DataContext.Set<T>();
}

protected IDatabaseFactory DatabaseFactory
{
    get; private set;
}

protected LearningCompactPilotContext DataContext
{
    get { return _dataContext ?? (_dataContext = DatabaseFactory.Get()); }
}

//... more code
}

//如何注册

builder.RegisterGeneric(typeof(RepositoryBase<>))
   .As(typeof(IRepository<>));

//如何使用
public class SomeService
{
    private readonly IRepository<SomeEntity> _repository;

    public SchoolService(IRepository<SomeEntity> repository)
    {
        this._repository= repository;
    }
}

如何注入泛型的Nloggger<T>  AS ILogger(动态类型注入)

public class LoggingModule : Autofac.Module
{
  private static void InjectLoggerProperties(object instance)
  {
    var instanceType = instance.GetType();

    // Get all the injectable properties to set.
    // If you wanted to ensure the properties were only UNSET properties,
    // here's where you'd do it.
    var properties = instanceType
      .GetProperties(BindingFlags.Public | BindingFlags.Instance)
      .Where(p => p.PropertyType == typeof(ILog) && p.CanWrite && p.GetIndexParameters().Length == 0);

    // Set the properties located.
    foreach (var propToSet in properties)
    {
      propToSet.SetValue(instance, LogManager.GetLogger(instanceType), null);
    }
  }

  private static void OnComponentPreparing(object sender, PreparingEventArgs e)
  {
    e.Parameters = e.Parameters.Union(
      new[]
      {
        new ResolvedParameter(
            (p, i) => p.ParameterType == typeof(ILog),
            (p, i) => LogManager.GetLogger(p.Member.DeclaringType)
        ),
      });
  }

  protected override void AttachToComponentRegistration(IComponentRegistry componentRegistry, IComponentRegistration registration)
  {
    // Handle constructor parameters.
    registration.Preparing += OnComponentPreparing;

    // Handle properties.
    registration.Activated += (sender, e) => InjectLoggerProperties(e.Instance);
  }
}

相同接口不同实现的如何注册使用

适配模式和装饰模式注册

适配模式

var builder = new ContainerBuilder();

// Register the services to be adapted
builder.RegisterType<SaveCommand>()
       .As<ICommand>()
       .WithMetadata("Name", "Save File");
builder.RegisterType<OpenCommand>()
       .As<ICommand>()
       .WithMetadata("Name", "Open File");

// Then register the adapter. In this case, the ICommand
// registrations are using some metadata, so we're
// adapting Meta<ICommand> instead of plain ICommand.
builder.RegisterAdapter<Meta<ICommand>, ToolbarButton>(
   cmd => new ToolbarButton(cmd.Value, (string)cmd.Metadata["Name"]));

var container = builder.Build();

// The resolved set of buttons will have two buttons
// in it - one button adapted for each of the registered
// ICommand instances.
var buttons = container.Resolve<IEnumerable<ToolbarButton>>();

装饰模式

var builder = new ContainerBuilder();

// Register the services to be decorated. You have to
// name them rather than register them As<ICommandHandler>()
// so the *decorator* can be the As<ICommandHandler>() registration.
builder.RegisterType<SaveCommandHandler>()
       .Named<ICommandHandler>("handler");
builder.RegisterType<OpenCommandHandler>()
       .Named<ICommandHandler>("handler");

// Then register the decorator. The decorator uses the
// named registrations to get the items to wrap.
builder.RegisterDecorator<ICommandHandler>(
    (c, inner) => new CommandHandlerDecorator(inner),
    fromKey: "handler");

var container = builder.Build();

// The resolved set of commands will have two items
// in it, both of which will be wrapped in a CommandHandlerDecorator.
var handlers = container.Resolve<IEnumerable<ICommandHandler>>();

还是使用泛型

var builder = new ContainerBuilder();

// Register the open generic with a name so the
// decorator can use it.
builder.RegisterGeneric(typeof(CommandHandler<>))
       .Named("handler", typeof(ICommandHandler<>));

// Register the generic decorator so it can wrap
// the resolved named generics.
builder.RegisterGenericDecorator(
        typeof(CommandHandlerDecorator<>),
        typeof(ICommandHandler<>),
        fromKey: "handler");

var container = builder.Build();

// You can then resolve closed generics and they'll be
// wrapped with your decorator.
var mailHandlers = container.Resolve<IEnumerable<ICommandHandler<EmailCommand>>>();

参考

MVC 4 Autofac and Generic Repository pattern

log4net Integration Module

Adapters and Decorators

How do I pick a service implementation by context?

Selectively resolving services at runtime with Autofac