golang实现各种情况的get请求操作

var (
 requestGetURLNoParams string = "http://httpbin.org/get"
 requestGetURL   string = "http://httpbin.org/get"
 imageURL    string = "http://httpbin.org/image"
)

// 基本get请求
func basicGet() {
 resp, err := http.Get(requestGetURLNoParams)
 if err != nil {
 log.Println("err")
 }
 defer resp.Body.Close()
 b, err := ioutil.ReadAll(resp.Body)
 if err != nil {
 log.Println("err")
 }
 fmt.Println(string(b))
}

// get请求参数放到 "net/url"
func basicGetURLParams() {
 params := url.Values{}
 parseURL, err := url.Parse(requestGetURLNoParams)
 if err != nil {
 log.Println("err")
 }
 params.Set("aaa", "aaa")
 params.Set("age", "23")
 //如果参数中有中文参数,这个方法会进行URLEncode
 parseURL.RawQuery = params.Encode()
 urlPathWithParams := parseURL.String()
 resp, err := http.Get(urlPathWithParams)
 if err != nil {
 log.Println("err")
 }
 defer resp.Body.Close()
 b, err := ioutil.ReadAll(resp.Body)
 if err != nil {
 log.Println("err")
 }
 fmt.Println(string(b))
}

// 可以设置请求头 添加cookie
func basicGetHeader() {
 client := http.Client{}
 req, err := http.NewRequest(http.MethodGet, requestGetURLNoParams, nil)
 if err != nil {
 log.Println("err")
 }
 // 添加请求头
 req.Header.Add("Content-type", "application/json;charset=utf-8")
 req.Header.Add("header", "header")
 // 添加cookie
 cookie1 := &http.Cookie{
 Name: "aaa",
 Value: "aaa-value",
 }
 req.AddCookie(cookie1)
 // 发送请求
 resp, err := client.Do(req)
 if err != nil {
 log.Println("err")
 }
 defer resp.Body.Close()
 b, err := ioutil.ReadAll(resp.Body)
 if err != nil {
 log.Println("err")
 }
 fmt.Println(string(b))
}

// ioutil.ReadAll(resp.Body) 先将所有的响应读出来放到内存中。如果文件太大，那么就会消耗很多内存
func basicGetDownloadFile() {
 client := http.Client{}
 req, err := http.NewRequest(http.MethodGet, imageURL, nil) // strings.NewReader(data)
 if err != nil {
 log.Println("err")
 }
 resp, err := client.Do(req)
 if err != nil {
 log.Println("err")
 }
 defer resp.Body.Close()
 b, err := ioutil.ReadAll(resp.Body)
 if err != nil {
 log.Println("err")
 }
 ioutil.WriteFile("./images/img.jpg", b, 0644)
}

// io.Copy() 省去了先把内容读取到内存，然后将内存中的内容写到文件
func basicGetDownloadFileIoCopy() {
 client := http.Client{}
 req, err := http.NewRequest(http.MethodGet, imageURL, nil)
 if err != nil {
 log.Println("err")
 }
 resp, err := client.Do(req)
 if err != nil {
 log.Println("err")
 }
 defer resp.Body.Close()
 // 创建一个文件用于保存
 dest, err := os.Create("./images/img.jpg")
 if err != nil {
 log.Println("err")
 }
 defer dest.Close()
 // 然后将响应流和文件流对接起来
 _, err = io.Copy(dest, resp.Body)
 if err != nil {
 log.Println("err")
 }
}

//基本的GET请求
package main
 
import (
 "fmt"
 "io/ioutil"
 "net/http"
 "time"
)
// HTTP get请求
func httpget(ch chan int){
 resp, err := http.Get("http://localhost:8000/rest/api/user")
 if err != nil {
  fmt.Println(err)
  return
 }
 defer resp.Body.Close()
 body, err := ioutil.ReadAll(resp.Body)
 fmt.Println(string(body))
 fmt.Println(resp.StatusCode)
 if resp.StatusCode == 200 {
  fmt.Println("ok")
 }
 ch <- 1
}
// 主方法
func main() {
 start := time.Now()
 // 注意设置缓冲区大小要和开启协程的个人相等
 chs := make([]chan int, 2000)
 for i := 0; i < 2000; i++ {
  chs[i] = make(chan int)
  go httpget(chs[i])
 }
 for _, ch := range chs {
  <- ch
 }
 end := time.Now()
 consume := end.Sub(start).Seconds()
 fmt.Println("程序执行耗时(s)：", consume)
}