blocks|key|1624087|text|我想你会想，如果事情真的属于会话状态，你会想。这是我经常做的事情，对于整个事情来说，这是一种很好的强类型方法，但在将内容放在会话上下文中时应该小心。不是因为它属于某个用户，所有的东西都应该出现在那里。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1624088|在global.asax中挂钩OnSessionStart事件|1624089|void+OnSessionStart(...)
{
++++HttpContext.Current.Session.Add("__MySessionObject",+new+MySessionObject());
}|code-block|syntax|javascript|1624090|从代码中任何HttpContext.Current属性!=+null的地方，您都可以检索该对象。我用一个扩展方法来做这件事。|1624091|public+static+MySessionObject+GetMySessionObject(this+HttpContext+current)
{
++++return+current+!=+null+?+(MySessionObject)current.Session["__MySessionObject"]+:+null;
}|1624092|这样你就可以在代码中|1624093|void+OnLoad(...)
{
++++var+sessionObj+=+HttpContext.Current.GetMySessionObject();
++++//+do+something+with+'sessionObj'
}|1624094|entityMap^0|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|T|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|U|8|@]|9|@]|A|$G|H]]|$1|I|3|J|5|6|7|V|8|@]|9|@]|A|$]]|$1|K|3|L|5|F|7|W|8|@]|9|@]|A|$G|H]]|$1|M|3|N|5|6|7|X|8|@]|9|@]|A|$]]|$1|O|3|P|5|F|7|Y|8|@]|9|@]|A|$G|H]]|$1|Q|3|-4|5|6|7|Z|8|@]|9|@]|A|$]]]|R|$]]

I would think you'll want to think about if things really belong in a session state. This is something I find myself doing every now and then and it's a nice strongly typed approach to the whole thing but you should be careful when putting things in the session context. Not everything should be there just because it belongs to some user.

in global.asax hook the OnSessionStart event

<pre><code>void OnSessionStart(...)
{
 HttpContext.Current.Session.Add("__MySessionObject", new MySessionObject());
}
</code></pre>

From anywhere in code where the HttpContext.Current property != null you can retrive that object. I do this with an extension method.

<pre><code>public static MySessionObject GetMySessionObject(this HttpContext current)
{
 return current != null ? (MySessionObject)current.Session["__MySessionObject"] : null;
}
</code></pre>

This way you can in code

<pre><code>void OnLoad(...)
{
 var sessionObj = HttpContext.Current.GetMySessionObject();
 // do something with 'sessionObj'
}
</code></pre>

blocks|key|1409417|text|虽然我不了解asp.net+mvc，但这是我们在一个普通的.net网站上应该做的事情。它应该也适用于asp.net+mvc。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1409418|YourSessionClass+obj=Session["key"]+as+YourSessionClass;
if(obj==null){
obj=new+YourSessionClass();
Session["key"]=obj;
}|code-block|syntax|javascript|1409419|为了便于访问，您可以将其放入一个方法中。HTH|1409420|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|L|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|M|8|@]|9|@]|A|$]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

Although I don't know about asp.net mvc, but this is what we should do in a normal .net website. It should work for asp.net mvc also.

<pre><code>YourSessionClass obj=Session["key"] as YourSessionClass;
if(obj==null){
obj=new YourSessionClass();
Session["key"]=obj;
}
</code></pre>

You would put this inside a method for easy access.
HTH

blocks|key|1624197|text|如果您使用的是asp.net+mvc，这里有一个访问会话的简单方法。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1624198|从控制器：|1624199|{Controller}.ControllerContext.HttpContext.Session["{name}"]|code-block|syntax|javascript|1624200|从视图：|1624201|<%25=Session["{name}"]+%25>|1624202|这绝对不是访问会话变量的最佳方式，但它是一种直接的方法。所以要谨慎使用它(最好是在快速原型开发期间)，并在合适的时候使用包装器/容器和OnSessionStart。|1624203|HTH|1624204|entityMap^0|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|T|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|U|8|@]|9|@]|A|$G|H]]|$1|I|3|J|5|6|7|V|8|@]|9|@]|A|$]]|$1|K|3|L|5|F|7|W|8|@]|9|@]|A|$G|H]]|$1|M|3|N|5|6|7|X|8|@]|9|@]|A|$]]|$1|O|3|P|5|6|7|Y|8|@]|9|@]|A|$]]|$1|Q|3|-4|5|6|7|Z|8|@]|9|@]|A|$]]]|R|$]]

If you are using asp.net mvc, here is a simple way to access the session.

From a Controller:

<pre><code>{Controller}.ControllerContext.HttpContext.Session["{name}"]
</code></pre>

From a View:

<pre><code>&lt;%=Session["{name}"] %&gt;
</code></pre>

This is definitely not the best way to access your session variables, but it is a direct route. So use it with caution (preferably during rapid prototyping), and use a Wrapper/Container and OnSessionStart when it becomes appropriate.

HTH

blocks|key|1409588|text|这里的答案是正确的，但是我很难在ASP.NET+MVC3应用程序中实现它。我想要访问控制器中的会话对象，但无法弄清楚为什么我一直收到“实例未设置为对象错误的实例”的消息。我注意到的是，在控制器中，当我尝试通过执行以下操作来访问会话时，我一直收到该错误。这是因为this.HttpContext是控制器对象的一部分。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1409589|this.Session["blah"]
//+or
this.HttpContext.Session["blah"]|code-block|syntax|javascript|1409590|但是，我想要的是属于System.Web名称空间的HttpContext，因为上面的答案建议在Global.asax.cs中使用它。因此，我必须显式地执行以下操作：|1409591|System.Web.HttpContext.Current.Session["blah"]|1409592|这对我很有帮助，我不确定我在这里做了什么不是作案手法的事情，但我希望它能帮助一些人！|1409593|entityMap^0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|O|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|Q|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|R|8|@]|9|@]|A|$E|F]]|$1|K|3|L|5|6|7|S|8|@]|9|@]|A|$]]|$1|M|3|-4|5|6|7|T|8|@]|9|@]|A|$]]]|N|$]]

The answer here is correct, I however struggled to implement it in an ASP.NET MVC 3 app. I wanted to access a Session object in a controller and couldn't figure out why I kept on getting a "Instance not set to an instance of an Object error". What I noticed is that in a controller when I tried to access the session by doing the following, I kept on getting that error. This is due to the fact that this.HttpContext is part of the Controller object. 

<pre><code>this.Session["blah"]
// or
this.HttpContext.Session["blah"]
</code></pre>

However, what I wanted was the HttpContext that's part of the System.Web namespace because this is the one the Answer above suggests to use in Global.asax.cs. So I had to explicitly do the following:

<pre><code>System.Web.HttpContext.Current.Session["blah"]
</code></pre>

this helped me, not sure if I did anything that isn't M.O. around here, but I hope it helps someone!

blocks|key|1409734|text|这些家伙的回答很棒，但我要提醒你不要总是依赖会话。这是快速和容易做到的，当然可以工作，但不是在所有的情况下都很好。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1409735|例如，如果你遇到一个场景，你的主机不允许使用会话，或者如果你在一个网络场，或者在一个共享的SharePoint应用程序的例子中。|1409736|如果您想要一种不同的解决方案，您可以考虑使用Castle+Windsor之类的IOC+Container，创建一个提供程序类作为包装器，然后根据您的需求使用每个请求或会话生活方式保留类的一个实例。|offset|length|1409737|IOC将确保每次返回相同的实例。|1409738|更复杂的是的，如果你需要一个简单的解决方案，只需要使用会话。|1409739|出于兴趣，下面是一些实现示例。|1409740|使用此方法，您可以创建一个提供程序类，如下所示：|1409741|public+class+CustomClassProvider+:+ICustomClassProvider
{
++++public+CustomClassProvider(CustomClass+customClass)
++++{+
++++++++CustomClass+=+customClass;
++++}

++++public+string+CustomClass+{+get;+private+set;+}
}|code-block|syntax|javascript|1409742|并注册如下所示：|1409743|public+void+Install(IWindsorContainer+container,+IConfigurationStore+store)
{
++++container.Register(
++++++++++++Component.For<ICustomClassProvider>().UsingFactoryMethod(
++++++++++++++++()+=>+new+CustomClassProvider(new+CustomClass())).LifestylePerWebRequest());
++++}|1409744|entityMap|0|LINK|mutability|MUTABLE|url|http://docs.castleproject.org/Windsor.MainPage.ashx|1|http://en.wikipedia.org/wiki/Inversion_of_control^0|0|0|M|E|0|13|D|1|0|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|18|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|19|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|1A|8|@]|9|@$F|1B|G|1C|1|1D]|$F|1E|G|1F|1|1G]]|A|$]]|$1|H|3|I|5|6|7|1H|8|@]|9|@]|A|$]]|$1|J|3|K|5|6|7|1I|8|@]|9|@]|A|$]]|$1|L|3|M|5|6|7|1J|8|@]|9|@]|A|$]]|$1|N|3|O|5|6|7|1K|8|@]|9|@]|A|$]]|$1|P|3|Q|5|R|7|1L|8|@]|9|@]|A|$S|T]]|$1|U|3|V|5|6|7|1M|8|@]|9|@]|A|$]]|$1|W|3|X|5|R|7|1N|8|@]|9|@]|A|$S|T]]|$1|Y|3|-4|5|6|7|1O|8|@]|9|@]|A|$]]]|Z|$10|$5|11|12|13|A|$14|15]]|16|$5|11|12|13|A|$14|17]]]]

Great answers from the guys but I would caution you against always relying on the Session. It is quick and easy to do so, and of course would work but would not be great in all cicrumstances.

For example if you run into a scenario where your hosting doesn't allow session use, or if you are on a web farm, or in the example of a shared SharePoint application.

If you wanted a different solution you could look at using an <a href="http://en.wikipedia.org/wiki/Inversion_of_control" rel="noreferrer">IOC Container</a> such as <a href="http://docs.castleproject.org/Windsor.MainPage.ashx" rel="noreferrer">Castle Windsor</a>, creating a provider class as a wrapper and then keeping one instance of your class using the per request or session lifestyle depending on your requirements.

The IOC would ensure that the same instance is returned each time.

More complicated yes, if you need a simple solution just use the session. 

Here are some implementation examples below out of interest.

Using this method you could create a provider class along the lines of:

<pre><code>public class CustomClassProvider : ICustomClassProvider
{
 public CustomClassProvider(CustomClass customClass)
 { 
 CustomClass = customClass;
 }

 public string CustomClass { get; private set; }
}
</code></pre>

And register it something like:

<pre><code>public void Install(IWindsorContainer container, IConfigurationStore store)
{
 container.Register(
 Component.For&lt;ICustomClassProvider&gt;().UsingFactoryMethod(
 () =&gt; new CustomClassProvider(new CustomClass())).LifestylePerWebRequest());
 }
</code></pre>

blocks|key|1624505|text|因为我不喜欢看到关于这个地方的"HTTPContext.Current.Session“，所以我使用单例模式来访问会话变量，它为您提供了一个易于访问的强类型数据包。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1624506|[Serializable]
public+sealed+class+SessionSingleton
{
++++#region+Singleton

++++private+const+string+SESSION_SINGLETON_NAME+=+"Singleton_502E69E5-668B-E011-951F-00155DF26207";

++++private+SessionSingleton()
++++{

++++}

++++public+static+SessionSingleton+Current
++++{
++++++++get
++++++++{
++++++++++++if+(+HttpContext.Current.Session[SESSION_SINGLETON_NAME]+==+null+)
++++++++++++{
++++++++++++++++HttpContext.Current.Session[SESSION_SINGLETON_NAME]+=+new+SessionSingleton();
++++++++++++}

++++++++++++return+HttpContext.Current.Session[SESSION_SINGLETON_NAME]+as+SessionSingleton;
++++++++}
++++}

++++#endregion

++++public+string+SessionVariable+{+get;+set;+}
++++public+string+SessionVariable2+{+get;+set;+}

++++//+...|code-block|syntax|javascript|1624507|然后，您可以从任何位置访问您的数据：|1624508|SessionSingleton.Current.SessionVariable+=+"Hello,+World!";|1624509|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|N|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|O|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|K|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|L|$]]

Because I dislike seeing "HTTPContext.Current.Session" about the place, I use a singleton pattern to access session variables, it gives you an easy to access strongly typed bag of data.

<pre><code>[Serializable]
public sealed class SessionSingleton
{
 #region Singleton

 private const string SESSION_SINGLETON_NAME = "Singleton_502E69E5-668B-E011-951F-00155DF26207";

 private SessionSingleton()
 {

 }

 public static SessionSingleton Current
 {
 get
 {
 if ( HttpContext.Current.Session[SESSION_SINGLETON_NAME] == null )
 {
 HttpContext.Current.Session[SESSION_SINGLETON_NAME] = new SessionSingleton();
 }

 return HttpContext.Current.Session[SESSION_SINGLETON_NAME] as SessionSingleton;
 }
 }

 #endregion

 public string SessionVariable { get; set; }
 public string SessionVariable2 { get; set; }

 // ...
</code></pre>

then you can access your data from anywhere:

<pre><code>SessionSingleton.Current.SessionVariable = "Hello, World!";
</code></pre>

blocks|key|1409869|text|您可以使用ViewModelBase作为所有模型的基类，这个类将负责从会话中提取数据|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1409870|class+ViewModelBase+
{
++public+User+CurrentUser+
++{
+++++get+{+return+System.Web.HttpContext.Current.Session["user"]+as+User+};
+++++set+
+++++{
++++++++System.Web.HttpContext.Current.Session["user"]=value;+
+++++}
++}
}|code-block|syntax|javascript|1409871|您可以在HttpContextBase上编写一个扩展方法来处理会话数据|1409872|T+FromSession<T>(this+HttpContextBase+context+,string+key,Action<T>+getFromSource=null)+
{
++++if(context.Session[key]!=null)+
++++{
++++++++return+(T)+context.Session[key];
++++}
++else+if(getFromSource!=null)+
++{
++++var+value+=+getFromSource();
+++context.Session[key]=value;+
+++return+value;+
+++}
++else+
++return+null;
}|1409873|在控制器中使用如下所示|1409874|User+userData+=+HttpContext.FromSession<User>("userdata",()=>+{+return+user+object+from+service/db++});+|1409875|第二个参数是可选的，当会话中没有值时，它将用于填充该键的会话数据。|1409876|entityMap^0|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|T|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|U|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|V|8|@]|9|@]|A|$E|F]]|$1|K|3|L|5|6|7|W|8|@]|9|@]|A|$]]|$1|M|3|N|5|D|7|X|8|@]|9|@]|A|$E|F]]|$1|O|3|P|5|6|7|Y|8|@]|9|@]|A|$]]|$1|Q|3|-4|5|6|7|Z|8|@]|9|@]|A|$]]]|R|$]]

You can use ViewModelBase as base class for all models , this class will take care of pulling data from session 

<pre><code>class ViewModelBase 
{
 public User CurrentUser 
 {
 get { return System.Web.HttpContext.Current.Session["user"] as User };
 set 
 {
 System.Web.HttpContext.Current.Session["user"]=value; 
 }
 }
}
</code></pre>

You can write a extention method on HttpContextBase to deal with session data 

<pre><code>T FromSession&lt;T&gt;(this HttpContextBase context ,string key,Action&lt;T&gt; getFromSource=null) 
{
 if(context.Session[key]!=null) 
 {
 return (T) context.Session[key];
 }
 else if(getFromSource!=null) 
 {
 var value = getFromSource();
 context.Session[key]=value; 
 return value; 
 }
 else 
 return null;
}
</code></pre>

Use this like below in controller 

<pre><code>User userData = HttpContext.FromSession&lt;User&gt;("userdata",()=&gt; { return user object from service/db }); 
</code></pre>

The second argument is optional it will be used fill session data for that key when value is not present in session.

blocks|key|1624595|text|我访问会话的方式是编写一个helper类，它封装了各种字段名称及其类型。我希望这个例子能有所帮助：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1624596|using+System;
using+System.Collections.Generic;
using+System.Web;
using+System.Web.SessionState;

namespace+dmkp
{
++++///+<summary>
++++///+Encapsulates+the+session+state
++++///+</summary>
++++public+sealed+class+LoginInfo
++++{
++++++++private+HttpSessionState+_session;
++++++++public+LoginInfo(HttpSessionState+session)
++++++++{
++++++++++++this._session+=+session;
++++++++}

++++++++public+string+Username
++++++++{
++++++++++++get+{+return+(this._session["Username"]+??+string.Empty).ToString();+}
++++++++++++set+{+this._session["Username"]+=+value;+}
++++++++}

++++++++public+string+FullName
++++++++{
++++++++++++get+{+return+(this._session["FullName"]+??+string.Empty).ToString();+}
++++++++++++set+{+this._session["FullName"]+=+value;+}
++++++++}
++++++++public+int+ID
++++++++{
++++++++++++get+{+return+Convert.ToInt32((this._session["UID"]+??+-1));+}
++++++++++++set+{+this._session["UID"]+=+value;+}
++++++++}

++++++++public+UserAccess+AccessLevel
++++++++{
++++++++++++get+{+return+(UserAccess)(this._session["AccessLevel"]);+}
++++++++++++set+{+this._session["AccessLevel"]+=+value;+}
++++++++}

++++}
}|code-block|syntax|javascript|1624597|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

My way of accessing sessions is to write a helper class which encapsulates the various field names and their types. I hope this example helps:

<pre><code>using System;
using System.Collections.Generic;
using System.Web;
using System.Web.SessionState;

namespace dmkp
{
 /// &lt;summary&gt;
 /// Encapsulates the session state
 /// &lt;/summary&gt;
 public sealed class LoginInfo
 {
 private HttpSessionState _session;
 public LoginInfo(HttpSessionState session)
 {
 this._session = session;
 }

 public string Username
 {
 get { return (this._session["Username"] ?? string.Empty).ToString(); }
 set { this._session["Username"] = value; }
 }

 public string FullName
 {
 get { return (this._session["FullName"] ?? string.Empty).ToString(); }
 set { this._session["FullName"] = value; }
 }
 public int ID
 {
 get { return Convert.ToInt32((this._session["UID"] ?? -1)); }
 set { this._session["UID"] = value; }
 }

 public UserAccess AccessLevel
 {
 get { return (UserAccess)(this._session["AccessLevel"]); }
 set { this._session["AccessLevel"] = value; }
 }

 }
}
</code></pre>

I am writing a web application that will allow a user to browse to multiple web pages within the website making certain requests. All information that the user inputs will be stored in an object that I created. The problem is that I need this object to be accessed from any part of the website and I don't really know the best way to accomplish this. I know that one solution is to use session variables but I don't know how to use them in asp .net MVC. And where would I declare a session variable? Is there any other way?

Session variables in ASP.NET MVC

我正在编写一个网络应用程序，将允许用户浏览到网站内的多个网页，使某些请求。用户输入的所有信息都将存储在我创建的对象中。问题是，我需要从网站的任何部分访问这个对象，而我真的不知道实现这一点的最好方法。我知道一个解决方案是使用会话变量，但我不知道如何在asp .net MVC中使用它们。我该在哪里声明会话变量呢？还有别的办...

问ASP.NET MVC中的会话变量
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