golang http request forwarding

In the development model where the front and back ends are separated, it is often necessary to send HTTP requests on the front end and respond on the back end. However, due to some reasons, sometimes the front end needs to communicate directly with the external system, so it is necessary to do so on the back end. The client forwards HTTP requests. This article will introduce how to use Golang to implement HTTP request forwarding.

First, we need to install the Golang environment and install the corresponding dependency packages. Next, we can start writing code.

package main

import (
    "log"
    "net/http"
)

func main() {
    http.HandleFunc("/", handleRequestAndRedirect)
    log.Fatal(http.ListenAndServe(":8080", nil))
}

func handleRequestAndRedirect(w http.ResponseWriter, r *http.Request) {
    url := "http://example.com" + r.URL.Path
    log.Printf("Redirecting to %s", url)

    req, err := http.NewRequest(r.Method, url, r.Body)
    if err != nil {
        http.Error(w, err.Error(), http.StatusInternalServerError)
        return
    }

    // 设置请求头
    for name, values := range r.Header {
        for _, value := range values {
            req.Header.Add(name, value)
        }
    }

    client := http.Client{}
    resp, err := client.Do(req)
    if err != nil {
        http.Error(w, err.Error(), http.StatusBadGateway)
        return
    }
    defer resp.Body.Close()

    // 将响应转发到客户端
    for name, values := range resp.Header {
        for _, value := range values {
            w.Header().Add(name, value)
        }
    }
    w.WriteHeader(resp.StatusCode)
    if _, err := io.Copy(w, resp.Body); err != nil {
        log.Printf("Error copying to client: %v", err)
    }
}

The above code implements a basic function of HTTP request forwarding. The handleRequestAndRedirect function in the code receives the request from the client and requests the specified external system according to the request path. The code reads the header of the HTTP request, adds relevant information to the request header, and sends the HTTP request using the http package in Go's standard library. Subsequently, the response from the external system is received and forwarded to the client. It is worth noting that this code also handles error conditions and returns error information to the client.

If we need to implement more functions, such as request retry, request logging, etc., we can modify the above code appropriately. In terms of request retry, we can add the logic to resend the request after the request fails; in terms of request logging, we can add code to record the request log.

In summary, this article implements an example of HTTP request forwarding based on Golang. This allows the front-end to communicate directly with external systems without the need for back-end forwarding, improving the accessibility of the front-end interface. Of course, in practical applications, we need to add more functions according to specific needs to adapt to complex business scenarios.

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