How to use curl in php? (Usage introduction)

How to use curl in php? The following article will summarize the usage of curl in php. It has certain reference value. Friends in need can refer to it. I hope it will be helpful to everyone.

1. Introduction to curl

The explanation given by Baidu Encyclopedia is: data transmission artifact. So where is its artifact? After searching the information, I found that curl can use the URL syntax to simulate a browser to transmit data. Because it simulates a browser, it supports a variety of network protocols. Currently supports http, https, ftp, gopher, telnet, dict, file and ldap protocols. libcurl also supports HTTPS authentication, HTTP POST, HTTP PUT, FTP upload (this can also be completed through PHP's FTP extension), HTTP form-based upload, proxy, cookies and username and password authentication.

The most commonly used method in PHP is curl to simulate get and post requests.

2. Usage

(1) If you want to use curl, the first step is to open curl in php and find it in the php configuration file php.ini extension=php_curl.dll, remove the ';' in front. Restart the server. Use phpinfo() to print in the php code, and find that the curl description in the picture is successfully opened.

(2) Using curl to complete a simple request is mainly divided into four major steps:

Initialization, creating a new curl resource.

Set the url and corresponding options

Grab the url and pass it to the browser

Close the curl resource. Release resources.

eg：

<?php
// 创建一个新cURL资源
$ch = curl_init();

// 设置URL和相应的选项
$options = array(CURLOPT_URL => &#39;http://www.example.com/&#39;,
                 CURLOPT_HEADER => false
                );

curl_setopt_array($ch, $options);

// 抓取URL并把它传递给浏览器
curl_exec($ch);

// 关闭cURL资源，并且释放系统资源
curl_close($ch);
?>

3. curl function

• curl_close - close a cURL session

• curl_copy_handle — Copies a cURL handle and all its options

• curl_errno — Returns the last error number

• curl_error — Returns a string that protects the most recent error in the current session

• curl_escape — URL-encodes the given string

• curl_exec — Execute a cURL Session

• curl_file_create — Create a CURLFile object

• curl_getinfo — Get information about a cURL connection resource handle

• curl_init — Initialize a cURL session

• curl_multi_add_handle — Add individual curl handles to a curl batch session

• curl_multi_close — Close a cURL session Group cURL handle

• curl_multi_exec — Runs a sub-connection of the current cURL handle

• curl_multi_getcontent — If CURLOPT_RETURNTRANSFER is set, returns the text of the fetched output Stream

• curl_multi_info_read — Get relevant transport information for the currently parsed cURL

• curl_multi_init — Return a new cURL batch handle

• curl_multi_remove_handle — Remove a handle resource in the curl batch handle resource

• ##curl_multi_select — Wait for active connections in all cURL batches

• curl_multi_setopt — Set an option for cURL parallel processing

• curl_multi_strerror — Return string describing error code

• curl_pause — Pause and unpause a connection

• curl_reset — Resets all options for a libcurl session handle

• curl_setopt_array — Sets options in bulk for a cURL transfer session

• curl_setopt — Set a cURL transfer option

• curl_share_close — Close a cURL share handle

##curl_share_init — Initialize a cURL share handle
curl_share_setopt — Set an option for a cURL share handle.
curl_strerror — Return string describing the given error code
curl_unescape — Decode the given URL-encoded string
curl_version — Get cURL version information

4. Example

1. Use curl to get the data

<?php
$url = &#39;http://www.example.com&#39;;
//初始化一个 cURL 对象 
$ch  = curl_init();
//设置你需要抓取的URL
curl_setopt($ch, CURLOPT_URL, $url);
// 设置cURL 参数，要求结果保存到字符串中还是输出到屏幕上。
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
//是否获得跳转后的页面
curl_setopt($ch, CURLOPT_FOLLOWLOCATION, 1);
$data = curl_exec($ch);
curl_close($ch);
echo $data;
?>

2. Use curl to post to get the data

<?php
function curl_post($url, $arr_data){
   $post_data = http_build_query($url_data);
   $ch = curl_init();
    curl_setopt($ch, CURLOPT_URL, $url);
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
    curl_setopt($ch, CURLOPT_POST, 1);
    curl_setopt($ch,  CURLOPT_POSTFLELDS, $post_data);
    $data = curl_exec($ch);
    curl_close($ch);
    echo $data;
}
$arr_post = array(
    &#39;name&#39;=>&#39;test_name&#39;,
    &#39;age&#39;   => 1
);
curl_post("http://www.explame.com/", $arr_post);
?>

3. Use proxy to crawl the page

Why use proxy to crawl? Take Google as an example. If you capture Google's data very frequently in a short period of time, you won't be able to capture it. When Google restricts your IP address, you can change the proxy and crawl again.

<?php
$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, "http://google.com"); 
curl_setopt($ch, CURLOPT_HEADER, false);  
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
//是否通过http代理来传输
curl_setopt($ch, CURLOPT_HTTPPROXYTUNNEL, TRUE);
curl_setopt($ch, CURLOPT_PROXY, 125.21.23.6:8080);  
//url_setopt($ch, CURLOPT_PROXYUSERPWD, &#39;user:password&#39;);如果要密码的话，加上这个  
$result=curl_exec($ch); 
curl_close($ch);
?>

4. Continue to maintain the session call of this site

In the case of synchronous user login, the session needs to be shared. If you want to continue to maintain the session of this site, then the sessionid must be placed in http Requesting

<?php
$session_str = session_name().&#39;=&#39;.session_id().&#39;; path=/; domain=.explame.com&#39;;
session_write_close(); //将数据写入文件并且结束session
$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, $url);
curl_setopt($ch, CURLOPT_HEADER, false);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
curl_setopt($ch, CURLOPT_COOKIE, $session_str); 
$ret = curl_exec($ch);
curl_close($ch);
?>

end

This article is reproduced from: https://blog.csdn.net/longgeaisisi/article/details/89330576

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