在Unity中，从Unity 取得的实例为 Transient。如果你希望使用多线程方式，就需要在组成时使用lifecycle参数，这时候取出的组件就不再是同一个了。在Unity IOC中，它支持我们对于组件的实例进行控制，也就是说我们可以透明的管理一个组件拥有多少个实例。Unity IOC容器提供了如下几种生命处理方式：

• Singleton：一个组件只有一个实例被创建，所有请求的客户使用程序得到的都是同一个实例。
• Transient：这种处理方式与我们平时使用new的效果是一样的，对于每次的请求得到的都是一个新的实例。
• Custom：自定义的生命处理方式。

我要增加一个Request的，一个Request请求一个实例，然后在Request结束的时候，回收资源。 增加一个Resquest级别的LifetimeManager，HttpContext.Items中数据是Request期间共享数据用的，所以HttpContext.Items中放一个字典，用类型为key，类型的实例为value。如果当前Context.Items中有类型的实例，就直接返回实例。 ObjectContext本身是有缓存的，整个Request内都是一个ObjectContext，ObjectContext一级缓存能力进一步利用。

用在Unity中，如何获取对象的实例及如何销毁对象都是由LifetimeManager完成的，其定义如下

public abstract class LifetimeManager : ILifetimePolicy, IBuilderPolicy
{protected LifetimeManager();public abstract object GetValue();public abstract void RemoveValue();public abstract void SetValue(object newValue);
}

其中GetValue方法获取对象实例，RemoveValue方法销毁对象，SetValue方法为对外引用的保存提供新的实例

有了这3个方法，就可以通过自定义LifetimeManager来实现从HttpContext中取值。

下面我们来实现Unity集成ADO.NET Entity Framework的工作：

1、利用Unity的依赖注入，ObjectContext会给我们生成3个构造函数，类似于下面的代码：

// Original file name:
// Generation date: 2008/8/24 10:05:33
namespace RequestLifeTimeManagerTest
{using Microsoft.Practices.Unity;/// <summary>/// There are no comments for AdventureWorksLTEntities in the schema./// </summary>public partial class AdventureWorksLTEntities : global::System.Data.Objects.ObjectContext{/// <summary>/// Initializes a new AdventureWorksLTEntities object using the connection string found in the 'AdventureWorksLTEntities' section of the application configuration file./// </summary>public AdventureWorksLTEntities() : base("name=AdventureWorksLTEntities", "AdventureWorksLTEntities"){this.OnContextCreated();}/// <summary>/// Initialize a new AdventureWorksLTEntities object./// </summary>public AdventureWorksLTEntities(string connectionString) : base(connectionString, "AdventureWorksLTEntities"){this.OnContextCreated();}/// <summary>/// Initialize a new AdventureWorksLTEntities object./// </summary>public AdventureWorksLTEntities(global::System.Data.EntityClient.EntityConnection connection) : base(connection, "AdventureWorksLTEntities"){this.OnContextCreated();}partial void OnContextCreated();……}构造函数注入包含了二种情况，一种是类仅有一个构造函数时，Unity 可以进行自动注入；另一种情况是，类包含多个构造函数时，必须使用 Attribute 或者配置文件指定注入时使用的构造函数。ObjectContext有多个构造函数，而且ObjectContext的构造函数代码是Visual Studio 代码生成的，最好的选择是使用配置文件或者使用配置API指定注入时使用的构造函数。下面是使用配置API：namespace RequestLifeTimeManagerTest
{public class EFContainerExtension : UnityContainerExtension   {protected override void Initialize(){this.Container.RegisterType<AdventureWorksLTEntities, AdventureWorksLTEntities>(new RequestControlledLifetimeManager(typeof(AdventureWorksLTEntities))).Configure<InjectedMembers>().ConfigureInjectionFor<AdventureWorksLTEntities>(new InjectionConstructor());}}
}我们定义了一个Unity扩展，在扩展类EFContainerExtension 我们选择了第一个构造函数以及ObjectContext使用RequestControlledLifetimeManager实现ObjectContext的生命周期管理。
2、实现RequestControlledLifetimeManager，完成对整个Request内都是一个ObjectContext的对象的生命周期管理：using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using Microsoft.Practices.Unity;
namespace RequestLifeTimeManagerTest
{public class RequestControlledLifetimeManager : LifetimeManager{private Type objectType;/// <summary>   ///    /// </summary>   /// <param name="t"></param>   public RequestControlledLifetimeManager(Type t){this.objectType = t;}private IDictionary<Type, object> GetObjectTable(){IDictionary<Type, object> objects = HttpContext.Current.Items[RequestLifeTimeManagerTest.UnityHttpModule.UNITYOBJECTS]as IDictionary<Type, object>;if (objects == null){lock (this){if (HttpContext.Current.Items[RequestLifeTimeManagerTest.UnityHttpModule.UNITYOBJECTS] == null){objects = new Dictionary<Type, object>();HttpContext.Current.Items[RequestLifeTimeManagerTest.UnityHttpModule.UNITYOBJECTS] = objects;}else{return HttpContext.Current.Items[RequestLifeTimeManagerTest.UnityHttpModule.UNITYOBJECTS]as IDictionary<Type, object>;}}}return objects;}public override object GetValue(){IDictionary<Type, object> objects = this.GetObjectTable();object obj = null;if (objects.TryGetValue(this.objectType, out obj)){return obj;}return null;}public override void RemoveValue(){IDictionary<Type, object> objects = this.GetObjectTable();object obj = null;if (objects.TryGetValue(this.objectType, out obj)){((IDisposable)obj).Dispose();objects.Remove(this.objectType);}}public override void SetValue(object newValue){IDictionary<Type, object> objects = this.GetObjectTable();objects.Add(this.objectType, newValue);}}
}写一个HttpMoudle,在Request结束的时候回收资源。using System;
using System.Web;
using System.Collections.Generic;namespace RequestLifeTimeManagerTest
{public class UnityHttpModule : IHttpModule{internal const string UNITYOBJECTS = "UNITYOBJECTS";#region IHttpModule Memberspublic void Dispose(){//clean-up code here.}public void Init(HttpApplication context){context.EndRequest += new EventHandler(context_EndRequest);}#endregionprivate void context_EndRequest(object sender, EventArgs e){IDictionary<Type, object> objects = HttpContext.Current.Items[UNITYOBJECTS]as IDictionary<Type, object>;if (objects != null){foreach (Type key in objects.Keys){if (objects[key] is IDisposable){((IDisposable)objects[key]).Dispose();}}HttpContext.Current.Items.Remove(UNITYOBJECTS);}}}
}3、web.config中的配置文件内容如下，注意看红色部分：<?xml version="1.0"?>
<configuration><configSections><sectionGroup name="system.web.extensions" type="System.Web.Configuration.SystemWebExtensionsSectionGroup, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"><sectionGroup name="scripting" type="System.Web.Configuration.ScriptingSectionGroup, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"><section name="scriptResourceHandler" type="System.Web.Configuration.ScriptingScriptResourceHandlerSection, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" requirePermission="false" allowDefinition="MachineToApplication" /><sectionGroup name="webServices" type="System.Web.Configuration.ScriptingWebServicesSectionGroup, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"><section name="jsonSerialization" type="System.Web.Configuration.ScriptingJsonSerializationSection, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" requirePermission="false" allowDefinition="Everywhere" /><section name="profileService" type="System.Web.Configuration.ScriptingProfileServiceSection, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" requirePermission="false" allowDefinition="MachineToApplication" /><section name="authenticationService" type="System.Web.Configuration.ScriptingAuthenticationServiceSection, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" requirePermission="false" allowDefinition="MachineToApplication" /><section name="roleService" type="System.Web.Configuration.ScriptingRoleServiceSection, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" requirePermission="false" allowDefinition="MachineToApplication" /></sectionGroup></sectionGroup></sectionGroup><section name="unity" type="Microsoft.Practices.Unity.Configuration.UnityConfigurationSection, Microsoft.Practices.Unity.Configuration" /></configSections><unity><typeAliases><typeAlias alias="string" type="System.String, mscorlib" /><typeAlias alias="singleton" type="Microsoft.Practices.Unity.ContainerControlledLifetimeManager, Microsoft.Practices.Unity" /><typeAlias alias="transient" type="Microsoft.Practices.Unity.TransientLifetimeManager, Microsoft.Practices.Unity" /></typeAliases><containers>   <container><types><type type="RequestLifeTimeManagerTest.Gateways.IProductGateway,RequestLifeTimeManagerTest" mapTo="RequestLifeTimeManagerTest.Gateways.ProductGateway, RequestLifeTimeManagerTest"></type></types><extensions><add type="RequestLifeTimeManagerTest.EFContainerExtension, RequestLifeTimeManagerTest" /></extensions></container></containers></unity><appSettings /><connectionStrings><add name="AdventureWorksLTEntities" connectionString="metadata=res://*/AdventureWorksModel.csdl|res://*/AdventureWorksModel.ssdl|res://*/AdventureWorksModel.msl;provider=System.Data.SqlClient;provider connection string=&quot;Data Source=GEFF-PC;Initial Catalog=AdventureWorksLT;Integrated Security=True;MultipleActiveResultSets=True&quot;" providerName="System.Data.EntityClient" /></connectionStrings><system.web><!-- Set compilation debug="true" to insert debugging symbols into the compiled page. Because this affects performance, set this value to true only during development.--><compilation debug="true"><assemblies><add assembly="System.Core, Version=3.5.0.0, Culture=neutral, PublicKeyToken=B77A5C561934E089" /><add assembly="System.Data.DataSetExtensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=B77A5C561934E089" /><add assembly="System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" /><add assembly="System.Xml.Linq, Version=3.5.0.0, Culture=neutral, PublicKeyToken=B77A5C561934E089" /><add assembly="System.Data.Entity, Version=3.5.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" /></assemblies></compilation><!--The <authentication> section enables configuration of the security authentication mode used by ASP.NET to identify an incoming user. --><authentication mode="Windows" /><!--The <customErrors> section enables configuration of what to do if/when an unhandled error occurs during the execution of a request. Specifically, it enables developers to configure html error pages to be displayed in place of a error stack trace.<customErrors mode="RemoteOnly" defaultRedirect="GenericErrorPage.htm"><error statusCode="403" redirect="NoAccess.htm" /><error statusCode="404" redirect="FileNotFound.htm" /></customErrors>--><pages><controls><add tagPrefix="asp" namespace="System.Web.UI" assembly="System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" /><add tagPrefix="asp" namespace="System.Web.UI.WebControls" assembly="System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" /></controls></pages><httpHandlers><!--<remove verb="*" path="*.aspx"/><add verb="*" path="*.aspx" type="RequestLifeTimeManagerTest.UnityHttpHandlerFactory, RequestLifeTimeManagerTest"/>--><remove verb="*" path="*.asmx" /><add verb="*" path="*.asmx" validate="false" type="System.Web.Script.Services.ScriptHandlerFactory, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" /><add verb="*" path="*_AppService.axd" validate="false" type="System.Web.Script.Services.ScriptHandlerFactory, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" /><add verb="GET,HEAD" path="ScriptResource.axd" type="System.Web.Handlers.ScriptResourceHandler, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" validate="false" /></httpHandlers><httpModules><add name="ScriptModule" type="System.Web.Handlers.ScriptModule, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" /><add name="UnityModule" type="RequestLifeTimeManagerTest.UnityHttpModule,RequestLifeTimeManagerTest"/>            </httpModules></system.web><system.codedom><compilers><compiler language="c#;cs;csharp" extension=".cs" warningLevel="4" type="Microsoft.CSharp.CSharpCodeProvider, System, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089"><providerOption name="CompilerVersion" value="v3.5" /><providerOption name="WarnAsError" value="false" /></compiler></compilers></system.codedom><!-- The system.webServer section is required for running ASP.NET AJAX under InternetInformation Services 7.0.  It is not necessary for previous version of IIS.--><system.webServer><validation validateIntegratedModeConfiguration="false" /><modules><remove name="ScriptModule" /><add name="ScriptModule" preCondition="managedHandler" type="System.Web.Handlers.ScriptModule, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" /></modules><handlers><remove name="WebServiceHandlerFactory-Integrated" /><remove name="ScriptHandlerFactory" /><remove name="ScriptHandlerFactoryAppServices" /><remove name="ScriptResource" /><add name="ScriptHandlerFactory" verb="*" path="*.asmx" preCondition="integratedMode" type="System.Web.Script.Services.ScriptHandlerFactory, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" /><add name="ScriptHandlerFactoryAppServices" verb="*" path="*_AppService.axd" preCondition="integratedMode" type="System.Web.Script.Services.ScriptHandlerFactory, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" /><add name="ScriptResource" preCondition="integratedMode" verb="GET,HEAD" path="ScriptResource.axd" type="System.Web.Handlers.ScriptResourceHandler, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" /></handlers></system.webServer><runtime><assemblyBinding xmlns="urn:schemas-microsoft-com:asm.v1"><dependentAssembly><assemblyIdentity name="System.Web.Extensions" publicKeyToken="31bf3856ad364e35" /><bindingRedirect oldVersion="1.0.0.0-1.1.0.0" newVersion="3.5.0.0" /></dependentAssembly><dependentAssembly><assemblyIdentity name="System.Web.Extensions.Design" publicKeyToken="31bf3856ad364e35" /><bindingRedirect oldVersion="1.0.0.0-1.1.0.0" newVersion="3.5.0.0" /></dependentAssembly></assemblyBinding></runtime>
</configuration>

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