golang 生成定单号

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年(2位)+一年中的第几天(3位)+指定位数随机数
风.foxwho

//生成单号
//06123xxxxx
//sum 最少10位,sum 表示全部单号位数
func MakeYearDaysRand(sum int) string {
    //年
    strs := time.Now().Format("06")
    //一年中的第几天
    days := strconv.Itoa(GetDaysInYearByThisYear())
    count := len(days)
    if count < 3 {
        //重复字符0
        days = strings.Repeat("0", 3-count) + days
    }
    //组合
    strs += days
    //剩余随机数
    sum = sum - 5
    if sum < 1 {
        sum = 5
    }
    //0~9999999的随机数
    ran := GetRand()
    pow := math.Pow(10, float64(sum)) - 1
    //fmt.Println("sum=>", sum)
    //fmt.Println("pow=>", pow)
    result := strconv.Itoa(ran.Intn(int(pow)))
    count = len(result)
    //fmt.Println("result=>", result)
    if count < sum {
        //重复字符0
        result = strings.Repeat("0", sum-count) + result
    }
    //组合
    strs += result
    return strs
}


//年中的第几天
func GetDaysInYearByThisYear() int {
    now := time.Now()
    total := 0
    arr := []int{31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31}
    y, month, d := now.Date()
    m := int(month)
    for i := 0; i < m-1; i++ {
        total = total + arr[i]
    }
    if (y%400 == 0 || (y%4 == 0 && y%100 != 0)) && m > 2 {
        total = total + d + 1

    } else {
        total = total + d
    }
    return total;
}