自定义Unity对象生命周期管理集成ADO.NET Entity Framework
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 Members
public void Dispose()
{
//clean-up code here.
}
public void Init(HttpApplication context)
{
context.EndRequest += new EventHandler(context_EndRequest);
}
#endregion
private 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="Data Source=GEFF-PC;Initial Catalog=AdventureWorksLT;Integrated Security=True;MultipleActiveResultSets=True"" 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 Internet
Information 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>
&nbs
<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>
