package main

import (
    "fmt"
    "io"
    "log"
    "net/http"
    "time"
)

// 發(fā)起一個(gè) GET 請(qǐng)求，并解析響應(yīng)
func fetchURL(url string) {
    // 創(chuàng)建自定義客戶端，設(shè)置超時(shí)
    client := http.Client{
        Timeout: 5 * time.Second,
    }

    // 創(chuàng)建請(qǐng)求
    req, err := http.NewRequest("GET", url, nil)
    if err != nil {
        log.Printf("創(chuàng)建請(qǐng)求失敗：%v\n", err)
        return
    }

    // 添加自定義頭部
    req.Header.Set("User-Agent", "Go-http-client/1.1")

    // 發(fā)起請(qǐng)求
    resp, err := client.Do(req)
    if err != nil {
        log.Printf("請(qǐng)求失?。?v\n", err)
        return
    }
    defer resp.Body.Close()

    // 輸出狀態(tài)碼和Header
    fmt.Printf("請(qǐng)求 URL: %s\n", url)
    fmt.Printf("響應(yīng)狀態(tài)碼: %d\n", resp.StatusCode)
    fmt.Println("響應(yīng)頭部:")
    for key, value := range resp.Header {
        fmt.Printf("  %s: %v\n", key, value)
    }

    // 讀取響應(yīng)體
    body, err := io.ReadAll(resp.Body)
    if err != nil {
        log.Printf("讀取響應(yīng)失?。?v\n", err)
        return
    }

    fmt.Println("響應(yīng)體內(nèi)容預(yù)覽（前500字）：")
    fmt.Println(string(body[:min(500, len(body))]))
    fmt.Println("--------------------------------------------------")
}

// 工具函數(shù)：取最小值
func min(a, b int) int {
    if a < b {
        return a
    }
    return b
}

func main() {
    urls := []string{
        "https://httpbin.org/get",
        "https://api.github.com",
        "https://example.com",
    }

    // 并發(fā)請(qǐng)求多個(gè)URL
    for _, url := range urls {
        go fetchURL(url)
    }

    // 防止主協(xié)程提前退出
    time.Sleep(6 * time.Second)
}

req.Header.Set("User-Agent", "Go-http-client/1.1")

client := http.Client{
    Timeout: 5 * time.Second,
}

請(qǐng)求 URL: https://httpbin.org/get
響應(yīng)狀態(tài)碼: 200
響應(yīng)頭部:
  Content-Type: [application/json]
  Server: [gunicorn/19.9.0]
響應(yīng)體內(nèi)容預(yù)覽（前500字）：
{
  "args": {}, 
  "headers": {
    "Accept-Encoding": "gzip", 
    "Host": "httpbin.org", 
    "User-Agent": "Go-http-client/1.1", 
    "X-Amzn-Trace-Id": "Root=1-xxxxxxxx"
  }, 
  "origin": "x.x.x.x", 
  "url": "https://httpbin.org/get"
}
--------------------------------------------------