利用Unity实现AOP

.NET程序中，可以利用Unity来实现AOP，用来进行日志、缓存或权限的处理。这里我们来写一个简单的程序，让其实现简单的AOP功能。

1.使用NuGet，在项目中获取Microsoft.Practices.Unity。

2.新建一个ITalk类及其实现

    public interface ITalk
    {
        string Speak(string msg);
    }


    public class Talk : ITalk
    {
        public string Speak(string msg)
        {
            Console.WriteLine(msg);
            return msg;
        }
    }

3.再进一个ServiceLocator类，用来实现接口的依赖反转

using Microsoft.Practices.Unity;
using Microsoft.Practices.Unity.Configuration;
using System;
using System.Collections.Generic;
using System.Configuration;
using System.Linq;
using System.Reflection;

namespace AopDemo
{
    /// <summary>
    /// Represents the Service Locator.
    /// </summary>
    public sealed class ServiceLocator : IServiceProvider
    {
        #region Private Fields
        private readonly IUnityContainer container;
        #endregion

        #region Private Static Fields
        private static readonly ServiceLocator instance = new ServiceLocator();
        #endregion

        #region Ctor
        /// <summary>
        /// Initializes a new instance of <c>ServiceLocator</c> class.
        /// </summary>
        private ServiceLocator()
        {
            UnityConfigurationSection section = (UnityConfigurationSection)ConfigurationManager.GetSection("unity");
            container = new UnityContainer();
            section.Configure(container);
        }
        #endregion

        #region Public Static Properties
        /// <summary>
        /// Gets the singleton instance of the <c>ServiceLocator</c> class.
        /// </summary>
        public static ServiceLocator Instance
        {
            get { return instance; }
        }
        #endregion

        #region Private Methods
        private IEnumerable<ParameterOverride> GetParameterOverrides(object overridedArguments)
        {
            List<ParameterOverride> overrides = new List<ParameterOverride>();
            Type argumentsType = overridedArguments.GetType();
            argumentsType.GetProperties(BindingFlags.Public | BindingFlags.Instance)
                .ToList()
                .ForEach(property =>
                {
                    var propertyValue = property.GetValue(overridedArguments, null);
                    var propertyName = property.Name;
                    overrides.Add(new ParameterOverride(propertyName, propertyValue));
                });
            return overrides;
        }
        #endregion

        #region Public Methods
        /// <summary>
        /// Gets the service instance with the given type.
        /// </summary>
        /// <typeparam name="T">The type of the service.</typeparam>
        /// <returns>The service instance.</returns>
        public T GetService<T>()
        {
            return container.Resolve<T>();
        }
        /// <summary>
        /// Gets the service instance with the given type by using the overrided arguments.
        /// </summary>
        /// <typeparam name="T">The type of the service.</typeparam>
        /// <param name="overridedArguments">The overrided arguments.</param>
        /// <returns>The service instance.</returns>
        public T GetService<T>(object overridedArguments)
        {
            var overrides = GetParameterOverrides(overridedArguments);
            return container.Resolve<T>(overrides.ToArray());
        }
        /// <summary>
        /// Gets the service instance with the given type by using the overrided arguments.
        /// </summary>
        /// <param name="serviceType">The type of the service.</param>
        /// <param name="overridedArguments">The overrided arguments.</param>
        /// <returns>The service instance.</returns>
        public object GetService(Type serviceType, object overridedArguments)
        {
            var overrides = GetParameterOverrides(overridedArguments);
            return container.Resolve(serviceType, overrides.ToArray());
        }
        #endregion

        #region IServiceProvider Members
        /// <summary>
        /// Gets the service instance with the given type.
        /// </summary>
        /// <param name="serviceType">The type of the service.</param>
        /// <returns>The service instance.</returns>
        public object GetService(Type serviceType)
        {
            return container.Resolve(serviceType);
        }

        #endregion
    }
}

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