java - 尝试使用 ImageIO 获取 StackOverflow 的 flair 图像时出现 403

Question

我在我的程序中写了下面的代码

url = new URL("http://stackoverflow.com/users/flair/3626698.png?theme=dark");
ImageIO.read(url);

出现以下错误

Exception in thread "main" javax.imageio.IIOException: Can't get input stream from URL!
    at javax.imageio.ImageIO.read(ImageIO.java:1395)
    at javaapplication1.JavaApplication1.main(JavaApplication1.java:25)
Caused by: java.io.IOException: Server returned HTTP response code: 403 for URL: https://stackoverflow.com/users/flair/3626698.png?theme=dark
....

我可以使用 wget 获取图像，通过在浏览器上写入 url 等...
我不明白为什么我在这里得到 403。

Answer 1

此 url 上的服务器可能会检查用户代理等属性，因此您会收到 403 错误，

note : in this case its working by just setting blank User-Agent property

试试这段代码

try {
  URL url = new URL("http://stackoverflow.com/users/flair/3626698.png?theme=dark");
  HttpURLConnection httpcon = (HttpURLConnection) url.openConnection(); 
  httpcon.addRequestProperty("User-Agent", ""); 
  BufferedImage image = ImageIO.read(httpcon.getInputStream());
  File outputfile = new File("image.jpg");
  ImageIO.write(image, "jpg", outputfile);   
 } 
 catch (Exception e) {
  e.printStackTrace();
 }