字符串到密钥的转换/反之亦然

只需遵循以下步骤。

`SecretKey secretKey = KeyGenerator.getInstance("ALGO_SECRET_KEY_GENERATOR").generateKey();
// Crate base64 string 
String encodedKey = Base64.getEncoder().encodeToString(secretKey.getEncoded());`

从字符串到键

`// decode base64 string
byte[] decodedKey = Base64.getDecoder().decode(encodedKey);
// rebuild key using SecretKeySpec
SecretKey originalKey = new SecretKeySpec(decodedKey, 0, decodedKey.length, "ALGO_SECRET_KEY_GENERATOR"); `

可从api版本8获得

`SecretKey secretKey = null;
                try {
                    secretKey = KeyGenerator.getInstance("AES").generateKey();
                } catch (NoSuchAlgorithmException e) {
                    e.printStackTrace();
                }

                byte encoded[] = secretKey.getEncoded();
                String str = android.util.Base64.encodeToString(encoded , 0);

                byte decoded[] = android.util.Base64.decode(str , 0);

                SecretKey originalKey = new SecretKeySpec(decoded, 0, decoded.length, "AES");'