为什么HttpWebRequest抛出异常而不返回HttpStatusCode.NotFound？

问题描述

我正在尝试使用HttpWebRequest验证网址的存在。我发现了一些基本上可以做到这一点的示例：

I'm trying to verify the existence of a Url using HttpWebRequest. I found a few examples that do basically this:

HttpWebRequest request = (HttpWebRequest)HttpWebRequest.Create(Url);
request.Method = "HEAD";
using (HttpWebResponse response = request.GetResponse() as HttpWebResponse)
{
    return response.StatusCode;
}

但是，如果URL确实损坏，则不会返回响应，而是

However, if the url is indeed broken, it's not returning a response, it's instead throwing an exception.

我将代码修改为：

try
{
    HttpWebRequest request = (HttpWebRequest)HttpWebRequest.Create(Url);
    request.Method = "HEAD";
    using (HttpWebResponse response = request.GetResponse() as HttpWebResponse)
    {
        return response.StatusCode;
    }
}
catch (System.Net.WebException ex)
{
    var response = ex.Response as HttpWebResponse;
    return response == null ? HttpStatusCode.InternalServerError : response.StatusCode;
}

这似乎终于可以满足我的要求。

which seems to finally do what I want.

但是我想知道，为什么请求抛出异常而不是返回带有NotFound状态码的响应？

But I would like to know, why is the request throwing an exception instead of returning the response with a NotFound status code?

推荐答案

是的，当网页大量使用状态代码并且并非全部都是错误时，这可能会很烦人。这会使身体加工变得很痛苦。我个人使用此扩展方法来获取响应。

Ya this can be quite annoying when web pages use status codes heavily and not all of them are errors. Which can make processing the body quite a pain. Personally I use this extension method for getting the response.

public static class HttpWebResponseExt
{
    public static HttpWebResponse GetResponseNoException(this HttpWebRequest req)
    {
        try
        {
            return (HttpWebResponse)req.GetResponse();
        }
        catch (WebException we)
        {
            var resp = we.Response as HttpWebResponse;
            if (resp == null)
                throw;
            return resp;
        }
    }
}

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