远程下载图片

转自：http://stackoverflow.com/questions/3615800/download-image-from-the-site-in-net-c

方法1：

string localFilename = @"c:\localpath\tofile.jpg";

using(WebClient client = new WebClient())

{

    client.DownloadFile("http://www.example.com/image.jpg", localFilename);

}

方法2：

private static void DownloadRemoteImageFile(string uri, string fileName)

{

    HttpWebRequest request = (HttpWebRequest)WebRequest.Create(uri);

    HttpWebResponse response = (HttpWebResponse)request.GetResponse();



    // Check that the remote file was found. The ContentType

    // check is performed since a request for a non-existent

    // image file might be redirected to a 404-page, which would

    // yield the StatusCode "OK", even though the image was not

    // found.

    if ((response.StatusCode == HttpStatusCode.OK || 

        response.StatusCode == HttpStatusCode.Moved || 

        response.StatusCode == HttpStatusCode.Redirect) &&

        response.ContentType.StartsWith("image",StringComparison.OrdinalIgnoreCase))

    {



        // if the remote file was found, download oit

        using (Stream inputStream = response.GetResponseStream())

        using (Stream outputStream = File.OpenWrite(fileName))

        {

            byte[] buffer = new byte[4096];

            int bytesRead;

            do

            {

                bytesRead = inputStream.Read(buffer, 0, buffer.Length);

                outputStream.Write(buffer, 0, bytesRead);

            } while (bytesRead != 0);

        }

    }

}