golang implements curl

In network programming, curl (Client for URLs, full name client URL) is an important command line tool used to obtain and send data, supporting various protocols and methods, such as HTTP, FTP, SMTP, etc. Curl's simplicity, ease of use and powerful functions make it widely used in web development, system management, crawlers and other fields.

In Golang programming, curl can be used to call the C language libcurl library to implement network requests. However, the curl function can also be implemented through the Go language native library. This article will introduce how to implement curl functions in Golang.

1. Implement HTTP GET request

HTTP GET request is the simplest and most common network request method. In Golang, HTTP GET requests can be implemented very conveniently using the net/http library. The following is a sample code:

package main

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

func main() {
    url := "http://www.example.com"
    resp, err := http.Get(url)
    if err != nil {
        fmt.Println("请求失败：", err)
        return
    }
    defer resp.Body.Close()

    body, err := ioutil.ReadAll(resp.Body)
    if err != nil {
        fmt.Println("读取响应失败：", err)
        return
    }

    fmt.Println("响应代码：", resp.StatusCode)
    fmt.Println("响应内容：", string(body))
}

In the above example, first use the http.Get function to send a GET request and determine whether the request has an error. Then, read the response Body through the ioutil.ReadAll function, and output the response code and response content at the end.

2. Implement HTTP POST request

HTTP POST request is often used to submit form data to the server, upload files, etc. In Golang, similar to HTTP GET requests, HTTP POST requests can be implemented using the Post function of the net/http library. The following is a sample code:

package main

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

func main() {
    url := "http://www.example.com"
    contentType := "application/x-www-form-urlencoded"
    body := url.Values{
        "username": {"admin"},
        "password": {"123456"},
    }.Encode()

    resp, err := http.Post(url, contentType, strings.NewReader(body))
    if err != nil {
        fmt.Println("请求失败：", err)
        return
    }
    defer resp.Body.Close()

    response, err := ioutil.ReadAll(resp.Body)
    if err != nil {
        fmt.Println("读取响应失败：", err)
        return
    }

    fmt.Println("响应代码：", resp.StatusCode)
    fmt.Println("响应内容：", string(response))
}

In the above example, the requested URL, Content-Type and request body are first defined (the map type Body is encoded into a string type through the url.Values.Encode function ). Then, use the http.Post function to send a POST request and parse the response.

3. Implement HTTP PUT request

HTTP PUT request is used in scenarios such as uploading files and updating resources. In Golang, similar to HTTP GET and POST requests, HTTP PUT requests can be implemented using the Do function of the net/http library. The following is a sample code:

package main

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

func main() {
    url := "http://www.example.com"
    contentType := "text/plain"
    body := "this is a put request"

    client := &http.Client{}
    req, err := http.NewRequest(http.MethodPut, url, bytes.NewBuffer([]byte(body)))
    if err != nil {
        fmt.Println("请求失败：", err)
        return
    }
    req.Header.Set("Content-Type", contentType)

    resp, err := client.Do(req)
    if err != nil {
        fmt.Println("请求失败：", err)
        return
    }
    defer resp.Body.Close()

    response, err := ioutil.ReadAll(resp.Body)
    if err != nil {
        fmt.Println("读取响应失败：", err)
        return
    }

    fmt.Println("响应代码：", resp.StatusCode)
    fmt.Println("响应内容：", string(response))
}

In the above example, the requested URL, Content-Type and request body are first defined. Then, use the http.NewRequest function to create an HTTP request object and set the request method, request headers, and request body. Finally, use the Do function of http.Client to send the HTTP request and parse the response.

To sum up, through the Golang native library, the curl function can be easily realized. The above example codes are just some simple examples. In actual applications, various exceptions, encoding and decoding, connection pooling and other issues need to be dealt with to improve the robustness and concurrency performance of the program.

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