Golang网络请求错误处理与重试机制

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func doWithRetry(client *http.Client, req *http.Request, maxRetries int) (*http.Response, error) {
    var resp *http.Response
    var err error
<pre class='brush:php;toolbar:false;'>for i := 0; i <= maxRetries; i++ {
    resp, err = client.Do(req)

    // 请求本身出错（如网络不通）
    if err != nil {
        if i == maxRetries {
            return nil, err
        }
        time.Sleep(100 * time.Millisecond * time.Duration(i)) // 指数退避
        continue
    }

    // 响应状态码为5xx，认为可重试
    if resp.StatusCode >= 500 {
        resp.Body.Close()
        if i < maxRetries {
            time.Sleep(100 * time.Millisecond * time.Duration(i))
            continue
        }
    }

    // 429 Too Many Requests 也适合重试
    if resp.StatusCode == 429 {
        resp.Body.Close()
        retryAfter := resp.Header.Get("Retry-After")
        delay := 1
        if retryAfter != "" {
            if sec, parseErr := strconv.Atoi(retryAfter); parseErr == nil {
                delay = sec
            }
        }
        time.Sleep(time.Duration(delay) * time.Second)
        continue
    }

    // 其他情况直接返回（包括4xx）
    break
}

return resp, err

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type RetryingRoundTripper struct {
    Transport http.RoundTripper
    MaxRetries int
}
<p>func (rt <em>RetryingRoundTripper) RoundTrip(req </em>http.Request) (<em>http.Response, error) {
var resp </em>http.Response
var err error
transport := rt.Transport
if transport == nil {
transport = http.DefaultTransport
}</p><pre class='brush:php;toolbar:false;'>for i := 0; i <= rt.MaxRetries; i++ {
    resp, err = transport.RoundTrip(req)
    if err == nil && resp.StatusCode < 500 && resp.StatusCode != 429 {
        return resp, nil
    }

    if i < rt.MaxRetries {
        time.Sleep(100 * time.Millisecond * time.Duration(i+1))
    } else {
        break
    }
}

return resp, err

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client := &http.Client{
    Transport: &RetryingRoundTripper{
        MaxRetries: 3,
    },
}
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