SVG从链接下载到文件失败，因为无效的base64？

Question

So I'm trying to download an SVG image it looks like base64 but fails. The URL is a lot longer than this but I shortened it for veiwers sake.

data:image/svg+xml;utf8,%3C%3Fxml%20version%3D%221.0%22%20encoding%3D%22UTF-8%22%20standalone%3D%22no%22%3F%3E%0A%3Csvg%20xmlns%3Axlink%3D%22http%3A%2F%2Fwww.w3.org%2F1999%2Fxlink%22%20height%3D%2232%22%20version%3D%221.1%22%20viewBox%3D%220%200%20320%20320%22%20wid3A%20%20%3Crect%20height%3D%22320%22%20id%3D%22rect%22%20rx%3D%2251.2%22%20width%3D%22320%22%20x%3D%220%22%20y%3D%220%22%2F%3E%0A%20%20%20%20%3CclipPath%20id%3D%22clip%22%3E%0A%20%20%20%20%20%20%3Cuse%20xlink%3Ahref%3D%22%23rect%22%2F%3E%0A%20%20%20%20%3C%2FclipPath%3E%0A%20%20%3C%2Fdefs%3E%0A%20%20%3Cuse%20fill%3D%22%23FFFC00%22%20stroke%3D%22black%22%20stroke-

Code:

foreach (var username in File.ReadAllLines("/Users/admin/Desktop/snap-scraper/snap-scraper/snapchats.txt"))
{
    Console.WriteLine($"Attempting to grab QR for {username}");

    driver.Navigate().GoToUrl($"https://snapchat.com/add/{username}");

    Thread.Sleep(1000);

    var htmlDocument = new HtmlDocument();
    htmlDocument.LoadHtml(driver.PageSource);

    var image = htmlDocument.DocumentNode.SelectSingleNode("//img");

    if (image == null || !image.Attributes.Contains("src"))
    {
        Console.WriteLine($"Something went wrong for {username}");
        continue;
    }

    Console.WriteLine($"Got the QR for {username} yay");

    var src = image.Attributes.Where(x => x.Name == "src").First().Value;

    string filePath = $"/Users/admin/Desktop/snap-scraper/snap-scraper/images/{username}.jpg";
    File.WriteAllBytes(filePath, Convert.FromBase64String(src.Replace("-", "")));
}

Answer 1

It's not Base64 . It's URL Encoding . You can see this in a URL Decoder Tool if you paste in the encoded URL.

Since SVG's are made up of an XML format they do not require encoding.

You can use WebUtility.UrlDecode(String) to decode the string and then convert it to bytes using Encoding.GetBytes(String) write the bytes to disk.

Example:

foreach (var username in File.ReadAllLines("/Users/admin/Desktop/snap-scraper/snap-scraper/snapchats.txt"))
{
    Console.WriteLine($"Attempting to grab QR for {username}");

    driver.Navigate().GoToUrl($"https://snapchat.com/add/{username}");

    Thread.Sleep(1000);

    var htmlDocument = new HtmlDocument();
    htmlDocument.LoadHtml(driver.PageSource);

    var image = htmlDocument.DocumentNode.SelectSingleNode("//img");

    if (image == null || !image.Attributes.Contains("src"))
    {
        Console.WriteLine($"Something went wrong for {username}");
        continue;
    }

    Console.WriteLine($"Got the QR for {username} yay");

    var src = image.Attributes.Where(x => x.Name == "src").First().Value;

    string filePath = $"/Users/admin/Desktop/snap-scraper/snap-scraper/images/{username}.svg"; // This was .jpg

    // URL Decode Image - Remember to strip the start of the data url e.g. data:image/svg xml;utf8,
    string svg = WebUtility.UrlDecode(src).replace("data:image/svg xml;utf8,", "");

    // Convert SVG to byte array
    byte[] svgBytes = Encoding.UTF8.GetBytes(decodedUrl);

    // Write to byte array to disk
    File.WriteAllBytes(filePath, svg);
}