自用简单的加密与解密

	public static void main(String[] args) {
        String str1 = encrypt("123456789", 3, true);

        String str2 = encrypt(str1, 3, false);
    }

    public static String encrypt(String original, int shift, boolean left) {

        StringBuilder encrypted = new StringBuilder();

        for (int i = 0; i < original.length(); i++) {
            char c = original.charAt(i);

            if (left) {
                c = (char) (c - shift);
                if (c < 'a') {
                    c = (char) (c + 58);
                }
            } else {
                c = (char) (c + shift);
                if (c > 'A') {
                    c = (char) (c - 58);
                }
            }

            encrypted.append(c);
        }

        return encrypted.toString();
    }