题目：
使用goroutine和channel实现-一个计算int64随机数各位数和的程序。
  1.开启一个goroutine循环生成int64类型的随机数，发送到jobChan
  2.开启3个goroutine从jobChan中取出随机数计算各位数的和，将结果发送到resultChan
  3.主goroutine从resultChan取出结果并打印到终端输出

解答：
type job struct {
   number int64
}

type worker struct {
   job    *job
   res int64
   i int
}

var jobChan = make(chan *job,100)
var resultChan = make(chan *worker,100)
var wg sync.WaitGroup
var once sync.Once

//开启一个goroutine循环生成int64类型的随机数，发送到jobChan
func create(jobChan chan<- *job )  {
   defer wg.Done()
   for i:=0; i<10; i++ {
      num := rand.Int63()
      newJob := &job{
         num,
      }
      jobChan<- newJob
      time.Sleep(time.Millisecond*500)
   }
   close(jobChan)
}

//开启3个goroutine从jobChan中取出随机数计算各位数的和，将结果发送到resultChan
func count(jobChan <-chan *job,resultChan chan<- *worker,i int)  {
   defer wg.Done()
   job, ok := <-jobChan
   for ok{
      sum:=int64(0)
      n:=job.number
      for n>0{
         sum+=n%10
         n=n/10
      }
      newWork := &worker{
         job: job,
         res: sum,
         i:i,
      }
      resultChan<- newWork
      job,ok = <-jobChan
   }
   once.Do(func() {close(resultChan)})
}

//主goroutine从resultChan取出结果并打印到终端输出
func main()  {
   wg.Add(1)
   go create(jobChan)
   wg.Add(3)
   for i:=1; i<=3; i++ {
      go count(jobChan,resultChan,i)
   }
   for result:=range resultChan{
      fmt.Printf("随机数为：%v,随机数各位和为：%v,这是第%v个协程：\n",result.job.number,result.res,result.i)
   }
   wg.Wait()
}