对比的Application_Start与OnInit的构造 [英] Application_Start versus OnInit versus constructor

问题描述

我已经发这个自从我开始年前编程传统的ASP 12（左右），我从来没有发现一个很好的解决方案，因为ASP和ASP.NET的架构一直是陋习沼泽，魔术共享单身，等我最大的问题是与<一个href=\"http://msdn.microsoft.com/en-us/library/system.web.httpapplication.aspx\"><$c$c>HttpApplication与非事件的事件对象（的Application_Start ， Application_End ，等等）。

I've gone rounds with this ever since I started programming classic ASP 12 (or so) years ago and I've never found a great solution because the architecture of ASP and ASP.NET has always been a swamp of bad practices, magic shared singletons, etc. My biggest issue is with the HttpApplication object with its non-event events (Application_Start, Application_End, etc.).

如果你想为HTTP应用程序的整个生命周期做的东西一次，的Application_Start 是明显的地方去做。对？不完全是。首先，这不是一个事件本身，这是一个神奇的命名约定，其次当，则此方法将每个由IIS创建的AppDomain调用一次。

If you want to do stuff once for the entire lifespan of an HTTP application, Application_Start is the obvious place to do it. Right? Not exactly. Firstly, this is not an event per se, it's a magic naming convention that, when followed, causes the method to be called once per AppDomain created by IIS.

除了神奇的命名规则是一个可怕的做法，我开始认为这可能是存在没有这样的东西在<$ C一开始事件原因$ C>的HttpApplication 对象。所以我尝试了确实存在的事件，如初始化。那么，这是不是一个真正的事件要么，这是一个重写的方法，这是未来最好的事情。

Besides magic naming conventions being a horrible practice, I've started to think it might be a reason there exist no such thing as a Start event on the HttpApplication object. So I've experimented with events that do exist, such as Init. Well, this isn't really an event either, it's an overridable method, which is the next best thing.

看来，的init（）方法被调用为的HttpApplication 对象的每个实例，这恰好一很多比每个AppDomain一次。这意味着，我干脆把我的启动逻辑中的的HttpApplication 对象的构造函数。

It seems that the Init() method is called for every instantiation of an HttpApplication object, which happens a lot more than once per AppDomain. This means that I might as well just put my startup logic inside the HttpApplication object's constructor.

现在我的问题是，为什么我不应该把我的启动逻辑中的构造？为什么连的init（）存在，我需要关心的Application_Start ？如果我这样做，任何人都可以解释为什么在的HttpApplication 对象这个伪事件没有适当的事件或重写的方法？

Now my question is, why shouldn't I put my startup logic in the constructor? Why does even Init() exist and do I need to care about Application_Start? If I do, can anyone explain why there is no proper event or overridable method for this pseudo-event in the HttpApplication object?

和任何人都可以向我解释为什么在一个典型的ASP.NET应用程序的8个实例我的的HttpApplication 创建（这会使构造和初始化跑就像很多次，当然，这可以通过锁定得到缓解，并称为共享静态布尔初始化）时，我的应用程序只有一个AppDomain中？

And can anyone explain to me why in a typical ASP.NET application, 8 instances of my HttpApplication are created (which causes the constructor and Init to run just as many times, of course; this can be mitigated with locking and a shared static boolean called initialized) when my application only has a single AppDomain?

推荐答案

调用的Application_Start第一次创建的HttpApplication实例，但不能在后续实例似乎有点一个黑客攻击。或许微软不想解释静态构造函数的人谁不真正想知道的概念。

Calling Application_Start the first time an instance of HttpApplication is created, but not on subsequent instances seems a bit of a hack. Perhaps Microsoft didn't want to explain the concept of a static constructor to people who didn't really want to know.

Application_End（），但是，似乎是必要的，因为没有C＃等效静态析/终结的。由于黑客去，这是没有那么糟糕。它只是闻起来有点滑稽。

Application_End(), however, seems to be a necessity, as there is no C# equivalent of a static destructor/finalizer. As hacks go, this isn't that bad. It just smells a little funny.

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