c# - 如何将依赖项名称作为构造函数参数注入(inject)

Question

使用 Autofac，我可以注册一个类来解析使用属性注入(inject)的接口(interface)，使用以下代码:

builder.RegisterType<Log4NetAdapter>()
       .As<ILogger>()
       .PropertiesAutowired()
       .InstancePerDependency();

但是，我的 Log4NetAdapter 类有一个需要调用类名称的构造函数参数。这样，我可以根据调用类的名称记录事件。

public class Log4NetAdapter : ILogger
{
    private readonly ILog _logger;

    public Log4NetAdapter(string logName)
    {
        _logger = LogManager.GetLogger(logName);
    }

    ...
}

如何将依赖项的名称(即 typeof(dependency).Name)注入(inject)到属性注入(inject)类的构造函数中，因为每个依赖项都有自己的 Log4NetAdapter实例？

Answer 1

更新:建立在LogInjectionModule sample 和 how Autofac does property injection ，我扩展了模块以执行构造函数和属性注入(inject)。

注意:我已经修复了传递给 LogManager 的类型在OnComponentPreparing使用声明类型。这使得例如Resolve<Func<Service>>使用正确的日志类型。

    using System.Linq;
    using log4net;

    public class LogInjectionModule : Module
    {
        protected override void AttachToComponentRegistration(IComponentRegistry registry, IComponentRegistration registration)
        {
            registration.Preparing += OnComponentPreparing;
            registration.Activating += OnComponentActivating;
        }

        private static void OnComponentActivating(object sender, ActivatingEventArgs<object> e)
        {
            InjectLogProperties(e.Context, e.Instance, false);
        }

        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))
                });
        }

        private static void InjectLogProperties(IComponentContext context, object instance, bool overrideSetValues)
        {
            if (context == null) throw new ArgumentNullException("context");
            if (instance == null) throw new ArgumentNullException("instance");

            var instanceType = instance.GetType();
            var properties = instanceType
                .GetProperties(BindingFlags.Public | BindingFlags.Instance)
                .Where(pi => pi.CanWrite && pi.PropertyType == typeof(ILog));

            foreach (var property in properties)
            {
                if (property.GetIndexParameters().Length != 0)
                    continue;

                var accessors = property.GetAccessors(false);
                if (accessors.Length == 1 && accessors[0].ReturnType != typeof(void))
                    continue;

                if (!overrideSetValues &&
                    accessors.Length == 2 &&
                    (property.GetValue(instance, null) != null))
                    continue;

                ILog propertyValue = LogManager.GetLogger(instanceType);
                property.SetValue(instance, propertyValue, null);
            }
        }
    }

关于如何使用该模块，这里有一个示例:

public class Service
{
    public Service(ILog log) { ... }
}

var cb = new ContainerBuilder();
cb.RegisterModule<LogInjectionModule>();
cb.RegisterType<Service>();
var c = cb.Build();

var service = c.Resolve<Service>();