生成订单号

	public static BigInteger generateRandom(int length) {
	    Random random = new Random();
	    char[] digits = new char[length];
	    digits[0] = (char) (random.nextInt(9) + '1');
	    for (int i = 1; i < length; i++) {
	        digits[i] = (char) (random.nextInt(10) + '0');
	    }
	    return new BigInteger(new String(digits));
	}

 

 

    private static String get6AnyString(){
        String str = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
        Random random = new Random();
        StringBuffer sb = new StringBuffer();

        for (int i = 0; i < 6; ++i) {
            int number = random.nextInt(62);// [0,62)
            sb.append(str.charAt(number));
        }
        return sb.toString();
    }