如果收到 HTTP 错误 403，如何在 JavaFx 中从 URL 加载图像

I was trying to help someone out with what I thought was a duplicate and a simple question, but it turned out to be slightly more complicated and I couldn't give a definite answer. Here is the original question.

I tried the code with different images on sites using the https protocol and none worked. I then took some images and added them to sites that use http protocol and they worked.

So, the questions is how do you load an image in a ImageView if the site hosting the image is using https protocol?

解决方案

It’s not an https issue. It seems cdn.discordapp.com requires a User-Agent header in the HTTP request. Furthermore, the site appears to only accept certain formats for User-Agent. It turns out the User-Agent supplied by wget is accepted:

Image createImage(String url)
throws IOException {
    URLConnection conn = new URL(url).openConnection();
    conn.setRequestProperty("User-Agent", "Wget/1.13.4 (linux-gnu)");

    try (InputStream stream = conn.getInputStream()) {
        return new Image(stream);
    }
}

Without a User-Agent header in the request, the site gives an HTTP 403 Forbidden response.