feat(cookie): 实现cookie计数器功能

- 添加了获取和设置cookie的处理函数
- 实现了counter cookie的递增逻辑
- 在每次请求时显示所有cookie信息
- 注册了/cookies路径的HTTP处理函数
- 处理cookie不存在时的初始化情况

24-httpserver/httpserver/cookies.go

@@ -0,0 +1,33 @@
+package main
+
+import (
+	"fmt"
+	"net/http"
+	"strconv"
+)
+
+func GetAndSetCookies(writer http.ResponseWriter, request *http.Request) {
+	counterVal := 1
+
+	counterCookie, err := request.Cookie("counter")
+	if err == nil {
+		counterVal, _ = strconv.Atoi(counterCookie.Value)
+		counterVal++
+	}
+	http.SetCookie(writer, &http.Cookie{
+		Name:  "counter",
+		Value: strconv.Itoa(counterVal),
+	})
+	if len(request.Cookies()) == 0 {
+		fmt.Fprintln(writer, "Request contains no cookies")
+	} else {
+		for _, cookie := range request.Cookies() {
+			fmt.Fprintf(writer, "Cookie Name: %s , Value: %s \n", cookie.Name, cookie.Value)
+		}
+	}
+	fmt.Fprintf(writer, "Total number of cookies: %d  counter Value: %v", len(request.Cookies()), counterVal)
+}
+
+func init() {
+	http.HandleFunc("/cookies", GetAndSetCookies)
+}