AOP之PostSharp7-解决IOC 不能直接new问题，简化IOC开发和IOC对象LazyLoad

经过几节的postsharp基础和每节的一个应用实例，已经基本PostSharp应用的能力，PostSharp主要是简化我们的开发，让编译器时候给我注入重复疲劳代码。  

   在今天我们的demo是，关于ioc（控制反转）的问题，ioc框架我们都会从ioc容器中取得我们的ioc对象注入，所以我们不能直接new对象得到我们的实例，必须Resolve。我一直都是很懒得人，既然有了PostSharp就的好好利用起来。大部份ioc逻辑是从以前的一篇利用Attribute简化Unity框架IOC注入转过来的，注入支持自定义配置文件，我个人不喜欢把配置信息全部写在一个web.config/app.config中，也不喜欢el的写在一个外部配置文件中，我个人倾向于每个模块在一个不能的配置文件，并在模块中在区分container容易，所以特别写了每个单独配置文件的延时加载，缓存。代码也不多，先上菜品：

View Code

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using Microsoft.Practices.Unity;
using Microsoft.Practices.Unity.Configuration;
using Microsoft.Practices.Unity.InterceptionExtension;

namespace PostSharpDemo
{
    [Serializable]
    public class IocUnityResolverAttribute : PostSharp.Aspects.LocationInterceptionAspect
    {
        private Dictionary<string, Microsoft.Practices.Unity.Configuration.UnityConfigurationSection> sectionCache = new Dictionary<string, Microsoft.Practices.Unity.Configuration.UnityConfigurationSection>();
        private static object lockObj = new object();
        public IocUnityResolverAttribute(string Container)
        {
            this.Container = Container;
        }

        public string Container
        {
            get;
            set;
        }

        public string ConfigFile
        {
            get;
            set;
        }

        public string Name
        {
            get;
            set;
        }

        public Microsoft.Practices.Unity.Configuration.UnityConfigurationSection GetUnityConfigurationSection()
        {
            if (!string.IsNullOrEmpty(this.ConfigFile))
            {
                Microsoft.Practices.Unity.Configuration.UnityConfigurationSection section = null;
                if (!sectionCache.ContainsKey(this.ConfigFile))
                {
                    lock (lockObj)
                    {
                        if (!sectionCache.ContainsKey(this.ConfigFile))
                        {
                            var fileMap = new System.Configuration.ExeConfigurationFileMap { ExeConfigFilename = System.IO.Path.Combine(System.AppDomain.CurrentDomain.BaseDirectory, this.ConfigFile) };
                            System.Configuration.Configuration configuration = System.Configuration.ConfigurationManager.OpenMappedExeConfiguration(fileMap, System.Configuration.ConfigurationUserLevel.None);
                            if (configuration == null)
                            {
                                throw new Exception(string.Format("Unity配置{0}不正确;", this.ConfigFile));
                            }
                            section = configuration.GetSection(Microsoft.Practices.Unity.Configuration.UnityConfigurationSection.SectionName) as Microsoft.Practices.Unity.Configuration.UnityConfigurationSection;
                            sectionCache.Add(this.ConfigFile, section);
                        }
                    }
                }
                return sectionCache[this.ConfigFile];
            }

            return System.Configuration.ConfigurationManager.GetSection(Microsoft.Practices.Unity.Configuration.UnityConfigurationSection.SectionName) as Microsoft.Practices.Unity.Configuration.UnityConfigurationSection;
        }

        public override void OnGetValue(PostSharp.Aspects.LocationInterceptionArgs args)
        {
            var current = args.GetCurrentValue();
            if (current == null)
            {
                var unitySection = this.GetUnityConfigurationSection();
                if (unitySection != null)
                {
                    var container = new Microsoft.Practices.Unity.UnityContainer().LoadConfiguration(unitySection, string.IsNullOrEmpty(Container) ? unitySection.Containers.Default.Name : Container);
                    var obj = string.IsNullOrEmpty(Name) ? container.Resolve(args.Location.LocationType) : container.Resolve(args.Location.LocationType, Name);
                    if (obj != null)
                    {
                        //var piabAtttr = obj.GetType().GetCustomAttributes(typeof(ELPolicyinjectionAttribute), false) as ELPolicyinjectionAttribute[];
                        //if (piabAtttr.Length > 0)
                        //{
                        //    obj = Microsoft.Practices.EnterpriseLibrary.PolicyInjection.PolicyInjection.Wrap(type, obj);
                        //}
                        args.Value = obj;
                        args.ProceedSetValue();
                    }
                }
            }
            args.ProceedGetValue();
        }

        public override bool CompileTimeValidate(PostSharp.Reflection.LocationInfo locationInfo)
        {
            var p = locationInfo.PropertyInfo;
            if (p != null)
            {
                var attrs = p.GetCustomAttributes(typeof(Microsoft.Practices.Unity.DependencyAttribute), true) as Microsoft.Practices.Unity.DependencyAttribute[];
                if (attrs != null && attrs.Length > 0)
                {
                    return true;
                }
            }
            return false;
        }
    }
}
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测试:

View Code

[IocUnityResolver("IocUnityResolver", ConfigFile = "App1.config")]
   class Program
   {
       [Microsoft.Practices.Unity.Dependency()]
       public static IIocUnityResolverAttributeTest IocUnityResolverAttributeTest
       {
           get;
           private set;

       }
       public static IIocUnityResolverAttributeTest IocUnityResolverAttributeTest2
       {
           get;
           private set;

       }

       static void Main(string[] args)
       {

Program.IocUnityResolverAttributeTest.Test("test ioc unity!");

        Console.Read();
    }
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效果：

另外多加一句在AOP之PostSharp初见-OnExceptionAspect这节我们系列开篇我们看了Postsharp的多播（），所以我们可以很轻松的应用于我们的程序集，类上加Attribute实现，但是这里必须要区分Location的的注入决策，所以这里重写的基类方法的CompileTimeValidate，在有EL Unity 中Microsoft.Practices.Unity.DependencyAttribute标签的location我们才会去植入。有了这些我们就很轻松的在各个类，程序集，命名空间引用。

看看我们上边的实例反编译效果，IocUnityResolverAttributeTest带有Microsoft.Practices.Unity.DependencyAttribute标签所以会植入，而IocUnityResolverAttributeTest2没有标签所以不会植入；

 

附件下载：demo

• AOP之PostSharp初见-OnExceptionAspect
• AOP之PostSharp2-OnMethodBoundaryAspect
• AOP之PostSharp3-MethodInterceptionAspect
• AOP之PostSharp4-实现类INotifyPropertyChanged植入
• AOP之PostSharp5-LocationInterceptionAspect
• AOP之PostSharp6-EventInterceptionAspect
• AOP之PostSharp7-解决IOC 不能直接new问题，简化IOC开发和IOC对象LazyLoad
• http://www.cnblogs.com/whitewolf/category/312638.html