How to recover a RSA public key from a byte[] array?
PublicKey publicKey =
KeyFactory.getInstance("RSA").generatePublic(new X509EncodedKeySpec(bytes));
For more info see this tutorial
For others who want to get private key instead of public key from byte array:
PrivateKey privateKey = KeyFactory.getInstance("RSA").generatePrivate(new PKCS8EncodedKeySpec(privateKeyBytes));