顺丰单号生成规则

顺丰的单号生成规则：顺丰单号目前12位，主要看倒数第二和第三位，我总结一下规律：如果倒数第二位为9是，看第三位进行相应的跳转（下面代码有注释），倒数第二位不为9，倒数第一位倒退一位。简单地做了个java版的递归

package com.qinsoft.test;

public class SFNext
{
    public static void main(String[] args)
    {
        SFNext sf = new SFNext();
        sf.MakeSFNextNo("594338721914");
    }
    private void MakeSFNextNo(String currentNo)
    {
        if (currentNo.length() == 12)
        {
            String newBehindFirstBit = null;
            String frontElevenBits = currentNo.substring(0, 11);
            String behindFirstBit = currentNo.substring(11, 12);
            String behindSecondBit = currentNo.substring(10, 11);
            String behindThirdBit = currentNo.substring(9, 10);
            if (behindSecondBit == "9")
            {
                switch (Integer.parseInt(behindThirdBit))
                {
                /* 倒数第三位0,1,2,4,5,7,8 跳转 4 */
                case 0:
                case 1:
                case 2:
                case 4:
                case 5:
                case 7:
                case 8:
                    newBehindFirstBit = MakeLastBit(behindFirstBit, 4);
                    break;
                /* 倒数第三位 3,6 跳转 5 */
                case 3:
                case 6:
                    newBehindFirstBit = MakeLastBit(behindFirstBit, 5);
                    break;
                /* 倒数第三位 9 跳转 7 */
                case 9:
                    newBehindFirstBit = MakeLastBit(behindFirstBit, 7);
                    break;
                }

            } else
            {
                newBehindFirstBit = MakeLastBit(behindFirstBit, 1);
            }
            int tempLength = frontElevenBits.length();
            long temp = Long.parseLong(frontElevenBits) + 1;
            String s =  ((temp+"".length() < tempLength) ? "0" + temp : temp) + newBehindFirstBit;
            System.out.println(s);
            MakeSFNextNo(s);
        } 
        else
        {
            System.out.println("没有单号了");
        }

    }

    private String MakeLastBit(String lastBit, int step)
    {
        int temp = Integer.parseInt(lastBit);
        if ((temp - step) >= 0)
        {
            return (temp - step)+"";
        } else
        {
            return (10 + (temp - step))+"";
        }
    }
}