package mainimport (    "fmt"    "math/rand")func main() {    ch := make(chan int)    done := make(chan bool)    f := make(chan bool)    go func() {        for {            select {            case ch <- rand.Intn(5):{                fmt.Println("随机生成数字")            }            case <-f:                {                    fmt.Println(111)                    return                }            default:            }        }    }()    go func() {        for i := 0; i < 5; i++ {            fmt.Println("Rand Number = ", <-ch) // Print number received on standard output        }        f <- true        done <- true // Send Terminate Signal and return        return    }()    <-done // Exit Main when Terminate Signal received}