asp.net - Asp.net HttpWebResponse - 我怎么能不依赖 WebException 进行流量控制？

Question

我需要检查请求是否会返回 500 服务器内部错误（因此会出现错误）。我正在这样做：

HttpWebRequest request = WebRequest.Create(url) as HttpWebRequest; 
request.Method = "GET";  
HttpWebResponse response = request.GetResponse() as HttpWebResponse; 

if (response.StatusCode == HttpStatusCode.OK)
     return true;
else 
    return false;

但是当我收到 500 Internal Server Error 时，会抛出一个 WebException，我不想依赖它来控制应用程序流 - 这怎么办？

Answer 1

我认为这篇 MSDN 文章会对您有所帮助：http:
//msdn.microsoft.com/en-us/library/system.net.webexception.status.aspx

Answer 2

事实上，鉴于 msdn 的示例，没有办法不依赖于控制流的异常。这是他们给出的例子：

try {
   // Create a web request for an invalid site. Substitute the "invalid site" strong in the Create call with a invalid name.
     HttpWebRequest myHttpWebRequest = (HttpWebRequest) WebRequest.Create("invalid site");

    // Get the associated response for the above request.
     HttpWebResponse myHttpWebResponse = (HttpWebResponse) myHttpWebRequest.GetResponse();
    myHttpWebResponse.Close();
}
catch(WebException e) {
    Console.WriteLine("This program is expected to throw WebException on successful run."+
                        "\n\nException Message :" + e.Message);
    if(e.Status == WebExceptionStatus.ProtocolError) {
        Console.WriteLine("Status Code : {0}", ((HttpWebResponse)e.Response).StatusCode);
        Console.WriteLine("Status Description : {0}", ((HttpWebResponse)e.Response).StatusDescription);
    }
}
catch(Exception e) {
    Console.WriteLine(e.Message);
}

显然，有时你确实必须走那条路。呃，好吧。