如何使用Go和http.Transport实现HTTP请求的日志记录？

package main

import (
    "log"
    "net/http"
    "net/http/httputil"
    "os"
    "time"
)

// LoggingTransport 实现了http.RoundTripper接口
type LoggingTransport struct {
    Transport http.RoundTripper
    Logger    *log.Logger
}

// RoundTrip 实现了http.RoundTripper接口的RoundTrip方法
func (t *LoggingTransport) RoundTrip(req *http.Request) (*http.Response, error) {
    startTime := time.Now()

    // 打印请求信息
    dump, err := httputil.DumpRequestOut(req, true)
    if err != nil {
        return nil, err
    }
    t.Logger.Println(string(dump))

    // 发送请求
    resp, err := t.Transport.RoundTrip(req)
    if err != nil {
        return nil, err
    }

    // 打印响应信息
    dump, err = httputil.DumpResponse(resp, true)
    if err != nil {
        return nil, err
    }
    t.Logger.Println(string(dump))

    // 计算请求耗时并打印
    duration := time.Since(startTime)
    t.Logger.Printf("Request took %s", duration)

    return resp, nil
}

func main() {
    // 创建自定义Transport
    transport := &LoggingTransport{
        Transport: http.DefaultTransport,
        Logger:    log.New(os.Stdout, "", log.LstdFlags),
    }

    // 创建自定义的http.Client
    client := &http.Client{
        Transport: transport,
    }

    // 创建自定义的http.Request
    req, err := http.NewRequest("GET", "http://www.example.com", nil)
    if err != nil {
        log.Fatal(err)
    }

    // 发送请求
    resp, err := client.Do(req)
    if err != nil {
        log.Fatal(err)
    }
    defer resp.Body.Close()

    // 处理响应
    // ...

}