java 生成任意位数随机数

/**
	 * 生成任意位数随机数
	 * @param code_len(位数)
	 * @return
	 */
	public static String validateCode(int code_len) {
		int count = 0;
		char str[] = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9' };
		StringBuffer pwd = new StringBuffer("");
		Random r = new Random();
		while (count < code_len) {
			int i = Math.abs(r.nextInt(10));
			if (i >= 0 && i < str.length) {
				pwd.append(str[i]);
				count++;
			}
		}
		return pwd.toString();
	}