duande2379
duande2379
2017-10-19 15:00

为什么我的随机数不更新?

已采纳

I am doing the following in Golang (hosted on Appengine)

Whenever I initiate the app by running dev_appserver command and I access the page at localhost:8080, I get a page with a new random number between 1 and 19. But on refreshing the page in the browser, this number does not change. If I kill the server and re-initiate by running dev_appserver, I get a new random number. How do I get the random number to update on page refresh.

Code follows:

package testpage

import (
    "fmt"
    "net/http"
    "math/rand"
    "time"
    "strconv"
)

func init() {
    http.HandleFunc("/", handler)
}

func handler(w http.ResponseWriter, r *http.Request) {
    fmt.Fprint(w, varHtml)
}
func random(min, max int) int {
    rand.Seed(time.Now().Unix())
    return rand.Intn(max - min) + min
}

var myrand = strconv.Itoa(random(1, 19))
var varHtml = `

Random number is ` + myrand 
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1条回答

  • dongye3917 dongye3917 4年前

    The varHtml is a package level variable and is calculated just once.

    You should move it to the handler as:

    func handler(w http.ResponseWriter, r *http.Request) {
        var varHtml = `Random number is ` + strconv.Itoa(random(1, 19))
        fmt.Fprint(w, varHtml)
    }
    

    Also there is no need to seed rand every time.

    It's better to do it at package init():

    func init() {
        rand.Seed(time.Now().Unix())
    }
    
    func random(min, max int) int {
        return rand.Intn(max - min) + min
    }
    
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