java查看到网站https的证书信息

public void () {
  try {
       URL url = new URL("https://www.baidu.com");
     HttpsURLConnection conn = (HttpsURLConnection) url.openConnection();
     conn.connect();
      Certificate[] certs = conn.getServerCertificates(); 
     X509Certificate cert = (X509Certificate) certs[0]; // cert[0]是证书链的最下层
       System.out.println("序号：" + cert.getSerialNumber());
      System.out.println("颁发给：" + cert.getSubjectDN().getName());
      System.out.println("颁发者：" + cert.getIssuerDN().getName());
       System.out.println("起始：" + cert.getNotBefore());
     System.out.println("过期：" + cert.getNotAfter());
      System.out.println("算法：" + cert.getSigAlgName());
        System.out.println("指纹：" + getThumbPrint(cert));
     conn.disconnect();
   } catch (Exception e) {
     // TODO Auto-generated catch block
      e.printStackTrace();
 }

}