Android AES加密 - 构造函数Base64（）不可见

Question

我找到了2个AES加密/解密功能，我想在我的应用中使用它们，但是我收到了错误。

功能是：

private static final String password = "test";
private static String salt;
private static int pswdIterations = 65536  ;
private static int keySize = 256;
private byte[] ivBytes;

////////////////
//encrypt AES///
////////////////
public String encrypt(String plainText) throws Exception {  

    //get salt
    salt = generateSalt();     
    byte[] saltBytes = salt.getBytes("UTF-8");

    // Derive the key
    SecretKeyFactory factory = SecretKeyFactory.getInstance("PBKDF2WithHmacSHA1");
    PBEKeySpec spec = new PBEKeySpec(
            password.toCharArray(),
            saltBytes,
            pswdIterations,
            keySize
            );

    SecretKey secretKey = factory.generateSecret(spec);
    SecretKeySpec secret = new SecretKeySpec(secretKey.getEncoded(), "AES");

    //encrypt the message
    Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
    cipher.init(Cipher.ENCRYPT_MODE, secret);
    AlgorithmParameters params = cipher.getParameters();
    ivBytes = params.getParameterSpec(IvParameterSpec.class).getIV();
    byte[] encryptedTextBytes = cipher.doFinal(plainText.getBytes("UTF-8"));
    return new Base64().encodeAsString(encryptedTextBytes);
}


@SuppressWarnings("static-access")
public String decrypt(String encryptedText) throws Exception {

    byte[] saltBytes = salt.getBytes("UTF-8");
    byte[] encryptedTextBytes = new Base64().decodeBase64(encryptedText);

    // Derive the key
    SecretKeyFactory factory = SecretKeyFactory.getInstance("PBKDF2WithHmacSHA1");
    PBEKeySpec spec = new PBEKeySpec(
            password.toCharArray(),
            saltBytes,
            pswdIterations,
            keySize
            );

    SecretKey secretKey = factory.generateSecret(spec);
    SecretKeySpec secret = new SecretKeySpec(secretKey.getEncoded(), "AES");

    // Decrypt the message
    Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
    cipher.init(Cipher.DECRYPT_MODE, secret, new IvParameterSpec(ivBytes));


    byte[] decryptedTextBytes = null;
    try {
        decryptedTextBytes = cipher.doFinal(encryptedTextBytes);
    } catch (IllegalBlockSizeException e) {
        e.printStackTrace();
    } catch (BadPaddingException e) {
        e.printStackTrace();
    }

    return new String(decryptedTextBytes);
}



public String generateSalt() {
    SecureRandom random = new SecureRandom();
    byte bytes[] = new byte[20];
    random.nextBytes(bytes);
    String s = new String(bytes);
    return s;
}    

我的错误在线：

return new Base64().encodeAsString(encryptedTextBytes);  

和

byte[] encryptedTextBytes = new Base64().decodeBase64(encryptedText);

错误消息是：构造函数Base64()不可见

知道为什么会这样吗？