code: public PublicKey getPublicKey_X509Encoded(byte[] keyBytes){  
         try {
             X509EncodedKeySpec spec = new X509EncodedKeySpec(keyBytes);  
             KeyFactory keyFactory = KeyFactory.getInstance(algorithm);  
             return keyFactory.generatePublic(spec);  
  		} catch (Exception e) {
  			log.error(e.getMessage(),e);
  		}
         return null;
      }
docs: 根据公钥字符串获取公钥
  Only RSAPublicKeySpec and X509EncodedKeySpec supported for RSA public keys
  @param publicKey
  @return