public static String generateRandomString(int aiLengh) {
        String lsRandomString = "";
        if (aiLengh > 0) {
            char[] larrRandomChar = new char[aiLengh];
            int c = 'A';
            int r1 = 0;
            for (int i = 0; i < aiLengh; i++) {
                r1 = (int) (Math.random() * 3);
                switch (r1) {
                    case 0:
                        c = '0' + (int) (Math.random() * 10);
                        break;
                    case 1:
                        c = 'a' + (int) (Math.random() * 26);
                        break;
                    case 2:
                        c = 'A' + (int) (Math.random() * 26);
                        break;
                }
                larrRandomChar[i] = (char) c;
            }
            lsRandomString = new String(larrRandomChar);
        }
        return lsRandomString;
    }