How to implement HTTP GET request in Golang

With the rapid development of the Internet, the development of Web applications has attracted more and more attention. For data interaction in web applications, the HTTP protocol is a very common method. For the back-end development of web applications, we usually need to use some programming languages ​​​​to implement the HTTP protocol. Among them, Golang (Go for short) is one of the more popular programming languages. It is characterized by fast speed and strong concurrency capabilities. It is very suitable for back-end development of web applications. So, how to implement HTTP GET request in Golang? Next, let’s explore it together.

Implementing HTTP GET requests in Golang usually requires the use of the net/http package, which provides various functions for sending HTTP requests to the web server and processing HTTP responses. The following is a simple example to demonstrate how to implement HTTP GET request in Golang:

package main

import (
    "fmt"
    "net/http"
    "io/ioutil"
)

func main() {
    resp, err := http.Get("https://www.example.com")
    if err != nil {
        fmt.Println("Get request failed!")
    } else {
        defer resp.Body.Close()
        body, err := ioutil.ReadAll(resp.Body)
        if err != nil {
            fmt.Println("Read response failed!")
        } else {
            fmt.Println(string(body))
        }
    }
}

In this example, we first introduce the two packages net/http and io/ioutil, and then call http The .Get() method sends a GET request with the URL "https://www.example.com". If the request is successful, an object of type *http.Response and an empty error object will be returned. We use the defer statement to ensure that the response resources are released after the function ends, and then call the ioutil.ReadAll() method to read the Body part of the response and convert it into a string type for output.

It should be noted that during the actual development process, we usually need to set some parameters for the HTTP GET request, such as Headers, Cookies, query string parameters, etc. The following is a more complete example of a Golang HTTP GET request for readers' reference:

package main

import (
    "fmt"
    "net/http"
    "io/ioutil"
)

func main() {
    req, err := http.NewRequest("GET", "https://www.example.com", nil)
    if err != nil {
        fmt.Println("New request failed!")
    } else {
        // 添加Headers
        req.Header.Add("User-Agent", "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/58.0.3029.110 Safari/537.3")
        req.Header.Add("Referer", "https://www.example.com")

        // 添加Cookies
        cookie := http.Cookie{Name: "name", Value: "value"}
        req.AddCookie(&cookie)

        // 添加查询字符串参数
        query := req.URL.Query()
        query.Add("page", "1")
        query.Add("size", "10")
        req.URL.RawQuery = query.Encode()

        // 发送请求
        client := &http.Client{}
        resp, err := client.Do(req)
        if err != nil {
            fmt.Println("Get request failed!")
        } else {
            defer resp.Body.Close()
            body, err := ioutil.ReadAll(resp.Body)
            if err != nil {
                fmt.Println("Read response failed!")
            } else {
                fmt.Println(string(body))
            }
        }
    }
}

Through the above example, we see that before sending an HTTP GET request, we can set some request parameters, such as Headers and Cookies , query string parameters, etc. For example, in the above example, we added Headers to the request through the req.Header.Add() method, added Cookies to the request through the req.AddCookie() method, and added cookies to the request through the req.URL.Query().Add() method. Added query string parameters to requests. In this way, after sending the request, the server will process it according to the parameters we set and return the corresponding response content.

Of course, in actual development, there are many things that need to be paid attention to, such as how to handle HTTP request errors, how to parse the Body part of the response, how to handle the returned error code, etc. But generally speaking, implementing HTTP GET requests in Golang is not very complicated. As long as you master some basic knowledge and operating skills, you can easily implement various HTTP GET requests.

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