如何妥善处置一WebResponse的实例？ [英] How to properly dispose of a WebResponse instance?

问题描述

通常，一个写code像这样使用一个WebRequest的下载一些数据。

Normally, one writes code something like this to download some data using a WebRequest.

using(WebResponse resp = request.GetResponse())  // WebRequest request...
   using(Stream str = resp.GetResponseStream())  
      ; // do something with the stream str

现在，如果引发WebException，该WebException具有参考WebResponse对象，这可能会或可能不会有所谓的Dispose（不同的地方除了已经发生，或如何响应类实现） - 我不知道知道了。

Now if a WebException is thrown, the WebException has a reference to the WebResponse object, which may or may not have Dispose called (depending on where the exception has happened, or how the response class is implemented) - I don't know.

我的问题是如何一个应该解决这个问题。是应该被编码非常防守和处置在WebException对象的反应（这将是一个有点古怪，因为WebException不是IDisposable接口）的。或者是一款应该忽略这一点，可能会访问一个释放的对象或从未处理一个IDisposable的对象呢？ MSDN文档WebException.Response中给出的例子是完全不够的。

My question is how one is supposed to deal with this. Is one supposed to be coding very defensively, and dispose of the response in the WebException object (that would be a little weird, as WebException is not IDisposable). Or is one supposed to ignore this, potentially accessing a disposed object or never disposing an IDisposable object? The example given in the MSDN documentation for WebException.Response is wholly inadequate.

推荐答案

我有一个快速浏览与反射，而现在可以说：

I have had a quick peek with Reflector, and can now say:

• WebResponse类，是一个抽象类，委托其全部关闭/处置行为，它的派生类。
• HttpWebResponse ，是你几乎可以肯定，这里使用的派生类，在其关闭/处置方法，是只关注配置和实际响应流。之类的状态，其余的可以留到GC的慈悲。

• WebResponse, being an abstract class, delegates all its closing/disposing behaviour to its derived classes.
• HttpWebResponse, being the derived class you are almost certainly using here, in its close/dispose methods, is only concerned with disposing the actual response stream. The rest of the class state can be left to the GC's tender mercies.

由此可见，它可能是安全的，做任何你喜欢就异常处理，只要：

It follows that it's probably safe to do whatever you like with regard to exception handling, as long as:

• 当你读 WebResponse类在尝试块中的响应流，封装在一个使用块。
• 的如果的你读 WebException 在抓块中的响应流，封闭它在一个使用块为好。
• 在没有必要担心处理 WebException 本身。

• When you read the response stream from WebResponse in the try block, enclose it in a using block.
• If you read the response stream from WebException in the catch block, enclose it in a using block as well.
• There is no need to worry about disposing of WebException itself.

这篇关于如何妥善处置一WebResponse的实例？的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！