golang set host

Golang is a fast, simple, and easy-to-use programming language. Its efficiency and development experience are widely welcomed by developers. During Golang development, we often encounter situations where we need to set up a host, such as deploying code locally for testing, or sending API requests to a designated server for production environment testing.

This article will introduce how to set host in Golang to help developers quickly solve this problem.

What is host

In network communications, host is the host name or IP address that is used to identify a computer on the network. In Golang, setting host means specifying the host name or IP address of the target host when initiating a network request so that the request can be sent to the target server correctly.

Golang's method of setting host

1. Use http.NewRequest

In Golang, use the http.NewRequest method to create a new HTTP request. This method requires three parameters:

• Request method (GET, POST, PUT, etc.)
• Request URL
• Optional request body (e.g. for POST form or JSON data)

In this method, you can use the url.URL.Parse method to parse the URL and set host to the target host name or IP address. The sample code is as follows:

import (
    "net/http"
    "net/url"
)

func main() {
    req, _ := http.NewRequest("GET", "http://example.com", nil)
    req.URL, _ = url.Parse("http://127.0.0.1:8080")
    client := &http.Client{}
    resp, _ := client.Do(req)
    defer resp.Body.Close()
    // 处理 HTTP 响应
}

In this sample code, we create a GET request, the request URL is "http://example.com", and then use the url.URL.Parse method to set the host to " 127.0.0.1:8080", and finally use http.Client to initiate a request and get the response.

2. Use http.DefaultTransport

In Golang, http.DefaultTransport is the default transport implementation of an HTTP client. By default, it uses the TCP protocol to transmit data, but you can also customize the client's transmission behavior using its Dial function. We can use this feature to set the host.

The sample code is as follows:

import (
    "net/http"
    "net"
)

func main() {
    transport := &http.Transport{
        Dial: func(network, address string) (net.Conn, error) {
            addr := "127.0.0.1:8080"
            return net.Dial(network, addr)
        },
    }
    client := &http.Client{Transport: transport}
    resp, _ := client.Get("http://example.com")
    defer resp.Body.Close()
    // 处理 HTTP 响应
}

In this sample code, we create an http.Transport instance and rewrite its Dial function to establish a connection using the specified IP address and port number . Then we create an http.Client instance and use the above transport as its Transport value. Finally, we use the Get method of http.Client to initiate a GET request and get the response.

Summary

This article shows two methods of setting host in Golang. Using these methods, developers can easily use different host names or IP addresses in development and testing, and can set different hosts for different requests. Through these techniques, the development efficiency of Golang programs will be greatly improved, making the code more readable and maintainable.

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