How to properly catch a 404 error in .NET

Question

I would like to know the proper way to catch a 404 error with c# asp.net here is the code I'm using

HttpWebRequest request = (HttpWebRequest) WebRequest.Create(String.Format("http://www.gravatar.com/avatar/{0}?d=404", hashe));

// execute the request
try
{
    //TODO: test for good connectivity first
    //So it will not update the whole database with bad avatars
    HttpWebResponse response = (HttpWebResponse)request.GetResponse();
    Response.Write("has avatar");
}
catch (Exception ex)
{
    if (ex.ToString().Contains("404"))
    {
         Response.Write("No avatar");
    }
}

This code works but I just would like to know if this is the most efficient.

Answer 1

StatusCode property is what I think, you are looking for.

Answer 2

See at MSDN about status of the response:

...
catch(WebException e) {
  Console.WriteLine("The following error occured : {0}",e.Status);  
}
...

Answer 3

I haven't tested this, but it should work

try
{
    // TODO: Make request.
}
catch (WebException ex)
{
    if (ex.Status == WebExceptionStatus.ProtocolError) {
        HttpWebResponse resp = ex.Response as HttpWebResponse;
        if (resp != null && resp.StatusCode == HttpStatusCode.NotFound)
        {
            // TODO: Handle 404 error.
        }
        else
            throw;
    }
    else
        throw;
}

Answer 4

Catch the proper exception type WebException:

try
{
    var request = (HttpWebRequest) WebRequest.Create(String.Format("http://www.gravatar.com/avatar/{0}?d=404", hashe));

    using(var response = (HttpWebResponse)request.GetResponse())
        Response.Write("has avatar");
}
catch(WebException e) 
{
  if(e.Response.StatusCode == 404) 
    Response.Write("No avatar");
}

Answer 5

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
    }
}