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in Technique[技术] by (71.8m points)

c# - How can I catch a 404?

I have the following code:

HttpWebRequest request = (HttpWebRequest)WebRequest.Create(url);
request.Method = "HEAD";
request.Credentials = MyCredentialCache;

try
{
    request.GetResponse();
}
catch
{
}

How can I catch a specific 404 error? The WebExceptionStatus.ProtocolError can only detect that an error occurred, but not give the exact code of the error.

For example:

catch (WebException ex)
{
    if (ex.Status != WebExceptionStatus.ProtocolError)
    {
        throw ex;
    }
}

Is just not useful enough... the protocol exception could be 401, 503, 403, anything really.

See Question&Answers more detail:os

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by (71.8m points)
try
{
    var request = WebRequest.Create(uri);
    using (var response = request.GetResponse())
    {
        using (var responseStream = response.GetResponseStream())
        {
            // Process the stream
        }
    }
}
catch (WebException ex)
{
    if (ex.Status == WebExceptionStatus.ProtocolError &&
        ex.Response != null)
    {
        var resp = (HttpWebResponse) ex.Response;
        if (resp.StatusCode == HttpStatusCode.NotFound)
        {
            // Do something
        }
        else
        {
            // Do something else
        }
    }
    else
    {
        // Do something else
    }
}

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