golang 使用 http socks 代理

实例如下：

package main

import (
	"fmt"
	"io/IoUtil"
	"net/http"
	"net/url"
)

const (
	HttpProxy  = "http://127.0.0.1:6152"
	SocksProxy = "socks5://127.0.0.1:6153"
)

func main() {
	proxy := func(_ *http.Request) (*url.URL,error) {
		return url.Parse(HttpProxy)
	}

	httpTransport := &http.Transport{
		Proxy: proxy,}

	httpClient := &http.Client{
		Transport: httpTransport,}

	req,err := http.NewRequest("GET","https://api.ip.sb/ip",nil)
	if err != nil {
		// handle error
	}

	resp,err := httpClient.Do(req)
	defer resp.Body.Close()

	body,err := IoUtil.ReadAll(resp.Body)
	if err != nil {
		// handle error
	}

	fmt.Println(string(body))

	proxy = func(_ *http.Request) (*url.URL,error) {
		return url.Parse(SocksProxy)
	}

	httpTransport = &http.Transport{
		Proxy: proxy,}

	httpClient = &http.Client{
		Transport: httpTransport,err = http.NewRequest("GET",err = httpClient.Do(req)
	defer resp.Body.Close()

	body,err = IoUtil.ReadAll(resp.Body)
	if err != nil {
		// handle error
	}

	fmt.Println(string(body))
}

可以验证：打印的响应中确实为代理 IP。