捕获和识别 HttpRequestException "The remote name could not be resolved: 'www.example.com'" 的正确方法是什么？

Question

我希望能够捕获并识别属于此特定类型的异常，然后 return 一条合适的错误消息。在 catch 块中执行此操作的正确方法是什么？

Answer 1

首先，在 catch 块中捕获 HttpRequestException

catch (HttpRequestException ex){}

然后如果您需要仔细识别消息，请使用 ex.Message

if (ex.Message.StartsWith("The remote name could not be resolved:"))
{
     //do the rest
{

Answer 2

您需要捕获的异常是 HttpRequestException 特别是 具有 InnerException 的 WebException 和 Status 属性值为 WebExceptionStatus.NameResolutionFailure.

幸运的是，使用 C# 6.0 exception filters，现在很容易只捕获满足这些特定条件的异常：

var hc=new HttpClient();
try
{
    (await hc.GetStringAsync("https://www.googggle.com"));

}
catch(HttpRequestException ex) 
  when ((ex.InnerException as WebException)?.Status ==
           WebExceptionStatus.NameResolutionFailure)
{
    //yay. localization-proof
    Console.WriteLine("dns failed");
}

捕获和识别 HttpRequestException "The remote name could not be resolved: 'www.example.com'" 的正确方法是什么？

What is the proper way to catch and identify the HttpRequestException "The remote name could not be resolved: 'www.example.com'"?

c#

asp.net

exception-handling