How to use Transport to customize HTTP requests in Golang?

In Go, you can use the Transport interface to customize HTTP requests. The specific steps are as follows: implement the RoundTrip method and specify custom behavior (add headers, connection restrictions, etc.); create a custom transport and implement the RoundTrip method; create an HTTP client using the custom transport; send a request and process the response.

Use Transport in Golang to customize HTTP requests

Introduction

In Go,# The ##net/http package provides a standard set of HTTP client and server types. However, sometimes you may need more granular control over HTTP requests. At this time, you can use the Transport interface to build a custom HTTP transport mechanism.

Transport interface

Transport The interface defines the methods required to perform and transmit HTTP requests:

type Transport interface {
    RoundTrip(*Request) (*Response, error)
}

where :

• RoundTrip method is responsible for executing the HTTP request and returning the response to the caller.

Custom Transport

To create a custom Transport, you need to implement the

RoundTrip method. In this method, you can specify custom behavior for the request, for example:

Add custom headers
• Set connection restrictions
• Use a proxy server
• Implementing the authentication mechanism

Practical case: Adding a custom header

Let us use a practical case to illustrate how to use Transport to add Custom header:

Code

import (
    "context"
    "fmt"
    "net/http"
    "net/http/httputil"
)

type CustomTransport struct {
    http.RoundTripper
}

func (t *CustomTransport) RoundTrip(req *http.Request) (*http.Response, error) {
    // 添加自定义标头
    req.Header.Add("X-Custom-Header", "custom-value")

    // 执行请求
    resp, err := t.RoundTripper.RoundTrip(req)
    if err != nil {
        return nil, err
    }

    // 打印带标头的请求内容
    dump, _ := httputil.DumpRequest(req, true)
    fmt.Println(string(dump))

    return resp, nil
}

func main() {
    // 创建自定义传输
    transport := &CustomTransport{http.DefaultTransport}

    // 创建具有自定义传输的 HTTP 客户端
    client := &http.Client{
        Transport: transport,
    }

    // 发送请求
    resp, err := client.Get("https://example.com")
    if err != nil {
        panic(err)
    }
    _ = resp.Body.Close()  // 关闭响应体
}

Output

When you run this code you will get in the console See the content of the HTTP request with custom headers.

GET https://example.com/ HTTP/1.1
Host: example.com
User-Agent: Go-http-client/1.1
X-Custom-Header: custom-value
...

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