How can I check if an Image exists at http://someu

问题:

How can I check if an Image exists at http://someurl/myimage.jpg in C#/ASP.NET It seems like there ought to be a method to check for this -- but I cannot find one.

I found this, but it doesn't really answer the question.

回答1:

This code should work:

private static bool UrlExists(string url)
{
    try
    {
        new System.Net.WebClient().DownloadData(url);
        return true;
    }
    catch (System.Net.WebException e)
    {
        if (((System.Net.HttpWebResponse)e.Response).StatusCode == System.Net.HttpStatusCode.NotFound)
            return false;
        else
            throw;
    }
}

回答2:

You could try using System.Net.WebRequest to send a 'HEAD" request to that to the url and check the response to see if the file exists - this should do the job without atually trying to download it.

回答3:

string fileextension = Path.GetExtension(filename);

if (fileextension.ToLower() == ".png" || fileextension.ToLower() == ".jpg" || fileextension.ToLower() == ".jpeg" || fileextension.ToLower() == ".gif" || fileextension.ToLower() == ".bmp"){}

回答4:

Maybe this or this might help. I don't think there's a direct command for images, but you could try using the FileExist method.

回答5:

You could use a System.Net.WebClient.DownloadFile function to try to load the image from the URL and see if you get an error. (Most likely a 404 Not Found error)

Its about the only way to do it from a URL. The System.IO namespace and all the functions in there are intended for files on a local machine or a network, so they would be useless to you in this situation.