go語言學習-簡單實現一個web服務器

package main

import (
	"fmt"
	"log"
	"net/http"
	"sync"
)

var mu sync.Mutex
var count int

func main() {
	http.HandleFunc("/", handler) //收到請求 / 路由後交由handler函數處理
	http.HandleFunc("/count", handler_count)
	log.Fatal(http.ListenAndServe("localhost:8080", nil)) //啓動http 服務
}

func handler(w http.ResponseWriter, r *http.Request) {
	mu.Lock()
	count++
	fmt.Fprintf(w, "url.path== %q\n", r.URL.Path) //格式化返回內容
	mu.Unlock()
	
	fmt.Fprintf(w, "%s %s %s\n", r.Method, r.URL, r.Proto)
	for k, v:= range r.Header{
		fmt.Fprintf(w, "Header[%q] = %q\n", k,v)
	}

	fmt.Fprintf(w, "Remote addr %q\n", r.RemoteAddr)
	if err := r.ParseForm(); err != nil{
		log.Print(err)
	}
	for k, v:= range r.Form{
		fmt.Fprintf(w, "Form[%q] = %q\n", k, v)
	}
}

func handler_count(w http.ResponseWriter, r *http.Request) {
	fmt.Fprintf(w, "count == %d\n", count)

}

注意：count是用來訪問計數

遍歷map時的key隨機化問題， 如果希望保證訪問順序，需要另外結束一個集合,例如

keys := make([]string, 0)

for k, _ := range map{ 

    keys = append(keys , k) 
}

for k := range keys {
    fmt.Println(k, map[k])
}