public String getCaptchaString(Integer stringCount) {
		String excludeChars = "Ii0o";
		if (stringCount <= 0) {
			throw new IllegalArgumentException("Character length must be > 0");
		}
		Integer endAscii = new Integer(122)+ 1;
		StringBuffer buf = new StringBuffer();
		char randomChar;
		while (stringCount-- != 0) {
			randomChar = (char) random.nextInt(endAscii);
			if (Character.isLetterOrDigit(randomChar)
					&& excludeChars.indexOf((int) randomChar) < 0) {
				buf.append(randomChar);
			} else {
				stringCount++;
			}
		}
		return buf.toString();
	}