c# - 我怎样才能 catch 404？

Question

我有以下代码:

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

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

如何捕获特定的 404 错误？ WebExceptionStatus.ProtocolError 只能检测到有错误发生，并不能给出错误的具体代码。

例如:

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

只是不够有用...协议(protocol)异常可能是 401、503、403，任何东西。

Answer 1

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
    }
}