如何在Golang中实现HTTP请求重试机制

package main
<p>import (
"net/http"
"time"
"log"
)</p><p>type RetryingRoundTripper struct {
Transport http.RoundTripper
MaxRetries int
RetryDelay time.Duration
}</p><p>func (r <em>RetryingRoundTripper) RoundTrip(req </em>http.Request) (<em>http.Response, error) {
var resp </em>http.Response
var err error
transport := r.Transport
if transport == nil {
transport = http.DefaultTransport
}</p><pre class="brush:php;toolbar:false;"><pre class="brush:php;toolbar:false;">for i := 0; i <= r.MaxRetries; i++ {
    resp, err = transport.RoundTrip(req)
    if err == nil {
        break
    }

    // 可在此加入对特定错误的判断，如网络超时、连接拒绝等
    log.Printf("Request failed (attempt %d): %v", i+1, err)

    if i < r.MaxRetries {
        time.Sleep(r.RetryDelay)
    }
}

return resp, err

func main() {
    client := &http.Client{
        Transport: &RetryingRoundTripper{
            MaxRetries: 3,
            RetryDelay: time.Second * 2,
        },
    }
<pre class="brush:php;toolbar:false;"><pre class="brush:php;toolbar:false;">resp, err := client.Get("https://httpbin.org/status/500")
if err != nil {
    log.Fatal("All attempts failed:", err)
}
defer resp.Body.Close()

log.Println("Request succeeded with status:", resp.Status)

if resp != nil && resp.StatusCode >= 500 {
    resp.Body.Close() // 需关闭旧响应体
    continue
}