public static void getColumnAlphabet(StringBuffer result, int columnIndex) {
		// 取余数

		int mod = columnIndex % ALPHABET.length;
		// 取商
		int quotient = columnIndex / ALPHABET.length;

		if (result == null) {
			result = new StringBuffer(quotient);
		}
		result.insert(0, ALPHABET[mod]);

		// 递归
		if (quotient == 0) {
			return;
		} else {
			getColumnAlphabet(result, (quotient - 1));
		}
	}