code: private static PublicKey commonGetPublickeyByText(String keyText)
              throws NoSuchAlgorithmException, InvalidKeySpecException {
          byte[] keyBytes = Base64.base64ToByteArray(keyText);
          X509EncodedKeySpec x509KeySpec = new X509EncodedKeySpec(keyBytes);
          KeyFactory keyFactory = KeyFactory.getInstance(RSA);
          return keyFactory.generatePublic(x509KeySpec);
      }
docs: (common)通过公钥文本获取公钥