如何作为一个构造函数参数注入的依赖名称 [英] How to inject dependency name as a constructor parameter

问题描述

使用Autofac，我注册类使用属性注入，使用下面的code，以解决对接口：

Using Autofac, I can register a class to resolve against an interface using property injection, using the following code:

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

不过，我的 Log4NetAdapter 类有需要调用类的名称的构造函数的参数。这样一来，我可以根据调用类的名称，记录事件。

However, my Log4NetAdapter class has a constructor parameter that requires the name of the calling class. This way, I can log events based upon the name of the calling class.

public class Log4NetAdapter : ILogger
{
    private readonly ILog _logger;

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

    ...
}

我怎么能注入的名称（即的typeof（依赖），请将.Name ）的依赖成性注入类的构造函数因为每个依赖都会有自己的 Log4NetAdapter 实例？

How can I inject the name (i.e. typeof(dependency).Name) of the dependency into the property-injected class' constructor given that each dependency will have its own Log4NetAdapter instance?

推荐答案

更新：建筑上的 LogInjectionModule 样品和<一href="http://$c$c.google.com/p/autofac/source/browse/Core/Source/Autofac/Core/Activators/Reflection/AutowiringPropertyInjector.cs"相对=nofollow> Autofac如何做物业注入，我已经扩展模块，以做到既构造和财产注入。

Update: Building on the LogInjectionModule sample and how Autofac does property injection, I have extended the module to do both constructor and property injection.

注：我在 OnComponent preparing 固定传递给日志管理类型使用声明类型。这使得如解析＆LT;函数功能：LT;服务＆GT;＆GT; 使用正确的日志类型。

Note: I've fixed the type passed to LogManager in OnComponentPreparing to use the declaring type. This makes e.g. Resolve<Func<Service>> use the correct log type.

    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);
            }
        }
    }

在如何使用该模块，这里有一个例子：

On how to use the module, here's a sample:

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>();

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