寫了個加密的方法，發現密鑰的長度有限制，有資料說必須是16的倍數，否則報錯，怎樣才能使密鑰的長度不受限制

public?static?String?jdkAES_Encrypt(String?source,?String?secretKey)?{
?
????????try?{
????????????byte[]?keyBytes?=?secretKey.getBytes();
????????????//?key轉換
????????????Key?key?=?new?SecretKeySpec(keyBytes,?"AES");
????????????Cipher?cipher?=?Cipher.getInstance("AES/ECB/PKCS5Padding");
????????????cipher.init(Cipher.ENCRYPT_MODE,?key);
????????????byte[]?result?=?cipher.doFinal(source.getBytes());
????????????System.out.println("密文Base64:"?+?Base64.encodeBase64String(result));
????????????return?Base64.encodeBase64String(result);
????????}?catch?(Exception?e)?{
????????????e.printStackTrace();
????????}
?
????????return?null;
????}