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 Fieldsprivate readonly IUnityContainer container;#endregion#region Private Static Fieldsprivate 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 Methodsprivate 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}
}

4.接下来是错误和缓存处理的类。我们这边只是简单的在控制台输出一句话，证明代码有执行。

ExceptionLoggingBehavior.cs

public class ExceptionLoggingBehavior : IInterceptionBehavior{public IEnumerable<Type> GetRequiredInterfaces(){return Type.EmptyTypes;}public IMethodReturn Invoke(IMethodInvocation input, GetNextInterceptionBehaviorDelegate getNext){Console.WriteLine("ExceptionLoggingBehavior");return getNext().Invoke(input, getNext);}public bool WillExecute{get { return true; }}}

CachingBehavior.cs

  public class CachingBehavior : IInterceptionBehavior{public IEnumerable<Type> GetRequiredInterfaces(){return Type.EmptyTypes;}public IMethodReturn Invoke(IMethodInvocation input, GetNextInterceptionBehaviorDelegate getNext){Console.WriteLine("CachingBehavior");return getNext().Invoke(input, getNext);}public bool WillExecute{get { return true; }}}

5.配置App.Config文件

<configuration><configSections><section name="unity" type="Microsoft.Practices.Unity.Configuration.UnityConfigurationSection, Microsoft.Practices.Unity.Configuration"/></configSections><startup> <supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.5" /></startup><!--BEGIN: Unity--><unity xmlns="http://schemas.microsoft.com/practices/2010/unity"><sectionExtension type="Microsoft.Practices.Unity.InterceptionExtension.Configuration.InterceptionConfigurationExtension, Microsoft.Practices.Unity.Interception.Configuration"/><container><extension type="Interception"/><!--Cache Provider--><register type="AopDemo.ITalk, AopDemo" mapTo="AopDemo.Talk, AopDemo"><interceptor type="InterfaceInterceptor"/><interceptionBehavior type="AopDemo.InterceptionBehaviors.CachingBehavior, AopDemo"/><interceptionBehavior type="AopDemo.InterceptionBehaviors.ExceptionLoggingBehavior, AopDemo"/></register></container></unity><!--END: Unity-->
</configuration>

6.调用

    static void Main(string[] args){ITalk talk = ServiceLocator.Instance.GetService<ITalk>();talk.Speak("Hello");}

7.结果

可以看到在打印出Hello前，代码先执行到了缓存与错误处理的方法。

PS：如果IOC的时候报类似错误

Exception is: InvalidOperationException - The type OAManageClient has multiple constructors of length 2. Unable to disambiguate.则配置文件应该增加<constructor></constructor>

 <register type="AopDemo.ITalk, AopDemo" mapTo="AopDemo.Talk, AopDemo"><interceptor type="InterfaceInterceptor"/><interceptionBehavior type="AopDemo.InterceptionBehaviors.CachingBehavior, AopDemo"/><interceptionBehavior type="AopDemo.InterceptionBehaviors.ExceptionLoggingBehavior, AopDemo"/>
        <constructor></constructor></register>