三种添加Cookie的方式(有其他方式请留言告知)：

服务端代码：

服务端很简单,请求时有Cookie则返回cookie的结果,withcookie为ture,没有则设置cookie,withcookie为false

package main

import (
	"fmt"
	"github.com/gin-gonic/gin"
)

func main(){
	engine := gin.Default()
	engine.GET("/cookie_test", func(context *gin.Context) {
		data:=map[string]string{}
		value,err:= context.Cookie("ds")
		if err!=nil	{
			context.SetCookie("ds","xxxxxxxx",10,"/","localhost",false,true)
			data["withcookie"] = "false"
			data["value"] = "xxxxxxxxxx"
			context.JSON(200,data)
		} else {
			fmt.Println("Request with cookie,value is:",value)
			data["withcookie"] = "true"
			data["value"] = value
			context.JSON(200,data)
		}
	})
	engine.Run(":8082")
}

一、Header中添加Cookie：

package main

import (
	"fmt"
	"io/ioutil"
	"net/http"
)

func main() {

	client := &http.Client{}

	req, _ := http.NewRequest("GET", "http://localhost:8082/cookie_test",nil)
	req.Header.Add("Cookie","ds=req.Header.Add")

	resp, err := client.Do(req)
	if err != nil {
		panic(nil)
	}

	body, _ := ioutil.ReadAll(resp.Body)
	defer resp.Body.Close()

	fmt.Println(string(body))

}

二、通过req添加Cookie：

package main

import (
	"fmt"
	"io/ioutil"
	"net/http"
)

func main() {

	client := &http.Client{}

	req, _ := http.NewRequest("GET", "http://localhost:8082/cookie_test",nil)
	req.AddCookie(&http.Cookie{
		Name:       "ds",
		Value:      "req.AddCookie",
		Path:       "/",
		Domain:     "localhost",
	})
	resp, err := client.Do(req)
	if err != nil {
		panic(nil)
	}

	body, _ := ioutil.ReadAll(resp.Body)
	defer resp.Body.Close()

	fmt.Println(string(body))

}

三、通过cookiejar来管理Cookie：

package main

import (
	"fmt"
	"io/ioutil"
	"net/http"
	"net/http/cookiejar"
	"net/url"
)

func main() {

	jar, _ := cookiejar.New(nil)
	var cookies []*http.Cookie

	firstCookie := &http.Cookie{
		Name:   "ds",
		Value:  "CookieJar",
		Path:   "/",
		Domain: "localhost",
	}

	cookies = append(cookies, firstCookie)

	cookieURL, _ := url.Parse("https://localhost:8082/cookie_test")
	//fmt.Println("cookie url is:",cookieURL)
	jar.SetCookies(cookieURL, cookies)

	// 查看添加结果
	fmt.Println(jar.Cookies(cookieURL))

	client := &http.Client{
		Jar: jar,
	}

	req, _ := http.NewRequest("GET", "http://localhost:8082/cookie_test",nil)
	resp, err := client.Do(req)
	if err != nil {
		panic(nil)
	}

	body, _ := ioutil.ReadAll(resp.Body)
	defer resp.Body.Close()

	fmt.Println(string(body))

}

Cookie自动管理Cookie：

将代码稍做改动，去掉预先设置的Cookie，发送两次请求

package main

import (
	"fmt"
	"io/ioutil"
	"net/http"
	"net/http/cookiejar"
)

func main() {

	jar, _ := cookiejar.New(nil)
	client := &http.Client{
		Jar: jar,
	}

	req, _ := http.NewRequest("GET", "http://localhost:8082/cookie_test",nil)
	resp, err := client.Do(req)
	if err != nil {
		panic(nil)
	}

	body, _ := ioutil.ReadAll(resp.Body)
	defer resp.Body.Close()

	fmt.Println(string(body))


	fmt.Println("-------------------------------------------------------------------------------------------------")


	req, _ = http.NewRequest("GET", "http://localhost:8082/cookie_test",nil)
	resp, err = client.Do(req)
	if err != nil {
		panic(nil)
	}

	body, _ = ioutil.ReadAll(resp.Body)
	resp.Body.Close()

	fmt.Println(string(body))

}

CookieJar的坑：

package main

import (
	"fmt"
	"net/http"
	"net/http/cookiejar"
	"net/url"
)

func main() {

	jar, _ := cookiejar.New(nil)
	var cookies []*http.Cookie

	firstCookie := &http.Cookie{
		Name:   "ds",
		Value:  "CookieJar",
		Path:   "/",
		Domain: "localhost",
	}

	cookies = append(cookies, firstCookie)

	cookieURL, _ := url.Parse("https://localhost:8082/cookie_test")
	fmt.Println("cookie url is:",cookieURL)
	jar.SetCookies(cookieURL, cookies)

	fmt.Println("Cookie is:", jar.Cookies(cookieURL))
}

上面的结果是没有问题的，但是我们把localhost改成127.0.0.1试试：

package main

import (
	"fmt"
	"net/http"
	"net/http/cookiejar"
	"net/url"
)

func main() {

	jar, _ := cookiejar.New(nil)
	var cookies []*http.Cookie

	firstCookie := &http.Cookie{
		Name:   "ds",
		Value:  "CookieJar",
		Path:   "/",
		Domain: "127.0.0.1",
	}

	cookies = append(cookies, firstCookie)

	cookieURL, _ := url.Parse("https://127.0.0.1:8082/cookie_test")
	fmt.Println("cookie url is:",cookieURL)
	jar.SetCookies(cookieURL, cookies)

	fmt.Println("Cookie is:", jar.Cookies(cookieURL))

}

结果为空，发请求的时候也不会带上Cookie，所以大家测试的时候不要填IP