How to use curl in php? Detailed explanation of curl extension course

CURL is a very powerful open source library that supports many protocols, including HTTP, FTP, TELNET, etc. We use it to send HTTP requests. The benefit it brings us is that we can set different HTTP protocol parameters through flexible options and supports HTTPS. CURL can automatically choose whether to encrypt the sent content based on whether the URL prefix is ​​"HTTP" or "HTTPS". Next, our php Chinese website will introduce friends to CURL.

Friends who are new to PHP can first read the website-related courses: php introductory tutorial one. Learn PHP in one week

# #You can watch related video tutorials about php Chinese website:

Dugu Jiujian (4)_PHP video tutorial

# #Basic process of sending a request using CURL

Using the PHP extension of CURL to complete sending an HTTP request generally has the following steps:

Initialize the connection handle;

Set CURL options;

Execute and get the results;

Release the VURL connection handle.

The following program fragment is a typical process of using CURL to send HTTP

// 1. 初始化
 $ch = curl_init();
 // 2. 设置选项，包括URL
 curl_setopt($ch,CURLOPT_URL,"http://www.php.cn");
 curl_setopt($ch,CURLOPT_RETURNTRANSFER,1);
 curl_setopt($ch,CURLOPT_HEADER,0);
 // 3. 执行并获取HTML文档内容
 $output = curl_exec($ch);
 if($output === FALSE ){
 echo "CURL Error:".curl_error($ch);
 }
 // 4. 释放curl句柄
 curl_close($ch);

Four functions are used in the above code

curl_init() and curl_close() are to initialize CURL respectively Connecting and closing CURL connections is relatively simple.

curl_exec() executes a CURL request. If no error occurs, the function returns the data returned by the corresponding URL, indicating satisfaction with a

string

; if an error occurs, the function returns FALSE. It should be noted that the equal sign is used to determine whether the output is FALSE. This is to distinguish between returning an empty string and an error. The most important function in the CURL function library is curl_setopt(), which can customize HTTP requests by setting options defined by the CURL function library. Three important options are used in the above code snippet:

CURLOPT_URL specifies the requested URL;
CURLOPT_RETURNTRANSFER is set to 1 to execute later. The return of the curl_exec function is the return string of the URL, instead of directing the return string to the standard output and returning TRUE;
CURLLOPT_HEADER is set to 0 to indicate that no HTTP header information is returned.
CURL has many options. You can check the php manual for a list of all options supported by CURL.

Get the output information of the CURL request

After the curl_exec() function is executed, you can use the curl_getinfo() function to obtain the relevant information output of the CURL request. The sample code is as follows:

curl_exec($ch);
$info = curl_getinfo($sh);
echo ' 获取 '.$info['url'].'耗时'.$info['total_time'].'秒';

In the above code, curl_getinfo returns an associative array, containing the following data:

url: network address.
content_type: Content encoding.
http_code:
• HTTP status code

  .

header_size: The size of the header.
request_size: The size of the request.
filetime: The time when the file was created.
ssl_verify_result: SSL verification result.
redirect_count: Jump count.
total_time: Total time taken.
namelookup_time: DNS query takes time.
connect_time: Time spent waiting for connection.
pretransfer_time: Pretransfer preparation time.
size_uplpad: The size of the uploaded data.
size_download: The size of the downloaded data.
speed_download: Download speed.
speed_upload: Upload speed.
download_content_length: The length of the download content.
upload_content_length: The length of the uploaded content.
starttransfer_time: Timetable to start transfer.
redirect_time: redirection takes time.
curl_getinfo() function also has an optional parameter $opt, through which you can set some constants, corresponding to the field above. If the second parameter is set, then return Only the specified information. For example, if $opt is set to CURLINFO_TOTAL_TIME, the curl_getinfo() function will only return total_time, which is the time consumed by the total transmission. When you only need to pay attention to certain transmission information, setting the $opt parameter is meaningful.

使用CURL发送GET请求

如何使用CURL来发送GET请求，发送GET请求的关键是拼装格式正确的URL。请求地址和GET数据由一个“?”分割,然后GET变量的名称和值用“=”分隔，各个GET名称和值由“&”连接。PHP为我们提供了一个函数专门用来拼装GET请求和数据部分——http_build_query,该函数接受一个关联数组，返回由该关联数据描述的GET请求字符串。使用这个函数，结合CURL发送HTTP请求的一般流程，我们封闭了一个发送GET请求的函数——doCurlGetRequest,具体代码如下：

**
 *@desc 封闭curl的调用接口，get的请求方式。
*/
function doCurlGetRequest($url,$data,$timeout = 5){
 if($curl == "" || $timeout <= 0){
 return false;
 }
 $url = $url.&#39;?&#39;.http_bulid_query($data);
 $con = curl_init((string)$url);
 curl_setopt($con, CURLOPT_HEADER, false);
 curl_setopt($con, CURLOPT_RETURNTRANSFER,true);
 curl_setopt($con, CURLOPT_TIMEOUT, (int)$timeout);
 
 return curl_exec($con);
}

这个函数把使用http_build_query 拼装好的带GET参数的URL传给curl_init函数，然后使用CURL发送HTTP请求。

使用CURL发送POST请求

可以使用CURL提供的选项CURLOPT_POSTFIELDS，设置该选项为POST字符串数据就可以把请求放在正文中。同样我们实现了一个发送POST请求的函数——doCurlPostRequest，代码如下：

/**
** @desc 封装 curl 的调用接口，post的请求方式
**/
function doCurlPostRequest($url,$requestString,$timeout = 5){
 if($url == &#39;&#39; || $requestString == &#39;&#39; || $timeout <=0){
 return false;
 }
 $con = curl_init((string)$url);
 curl_setopt($con, CURLOPT_HEADER, false);
 curl_setopt($con, CURLOPT_POSTFIELDS, $requestString);
 curl_setopt($con, CURLOPT_POST,true);
 curl_setopt($con, CURLOPT_RETURNTRANSFER,true);
 curl_setopt($con, CURLOPT_TIMEOUT,(int)$timeout);
 return curl_exec($con); 
}

上面代码中除了设置CURLOPT_POSTFIELDS外，我们还设置了CURL_POST为true,标识这个请求是一个POST请求。在POST请求中也是可以传输GET数据的，只需要在URL中拼装GET请求数据即可秀。

curl实现的扩展功能：

1、实现远程获取和采集内容

2、实现PHP 网页版的FTP上传下载

3、实现模拟登陆：去一个邮件系统，curl可以模拟cookies

4、实现接口对接（API），数据传输等：通过一个平台发送短信啊，抓取和传递所传输的信息。

5、实现模拟Cookie等：登陆的状态下才可以操作一些属性。

如何使用CURL功能：

默认情况加PHP是不支持CURL的，需要在php.ini中开启该功能

;extension=php_curl.dll前面的分号去掉

1 整个操作过程中第一步是用cur_init()函数进行初始化

$curl = curl_init(‘www.php.cn')

2.用curl_setopt（）函数进行设置选项。

3.设置后，进行执行事务 curl_exec($curl);

4 最后关闭curl_close();

使用PHP CURL实现传输和获取功能（post传输方式）：获取远程网页数据

$user = "admin";
$pass = "admin";
$curlPost = "user=$user&pass=$pass";
$ch = curl_init(); //初始化一个CURL对象
curl_setopt($ch, CURLOPT_URL, "http://localhost/edu/login.php");
//设置你所需要抓取的URL
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 0);
//设置curl参数，要求结果是否输出到屏幕上，为true的时候是不返回到网页中
假设上面的0换成1的话，那么接下来的$data就需要echo一下。
curl_setopt($ch, CURLOPT_POST, 1);
//post提交
curl_setopt($ch, CURLOPT_POSTFIELDS, $curlPost);
$data = curl_exec($ch);
//运行curl,请求网页。
curl_close($ch);
[/code]

实现远程模拟登陆最基础部分。

curl也还是需要配置用户名和密码的，只不过是被浏览器隐藏了。

============================================================================

curl模拟登陆

模拟登陆：就是不登陆到php的论坛，也能查看到相应的信息。

分析登陆字段--->登陆后保留cookie状-->读取cookie并跳转到相关页-->抓取数

1、模拟登陆后创建一个文件保存cookie内容

2、通过读取生成的cookie内容模拟用户登陆状态

3、到相关页面获取所需内容

tempname创建一个临时文件

tempnam() 函数创建一个具有唯一文件名的临时文件。 若成功，则该函数返回新的临时文件名。若失败，则返回 false。

tempnam(dir,prefix)

参数 描述

dir 必需。规定创建临时文件的目录。

prefix 必需。规定文件名的开头。

相当于，fopen  fwirte  fclose

它可以返回一个布尔值。使用第三方来登陆你的QQ、msn是很危险的，因为它可以记录你的登录状态，抓取你的用户名和密码。

使用CURL模拟登陆到PHP论坛

1、分析登陆所需input框字段名和所需字段数量

2、保存cookie 模拟登陆后获取会员金币数量

代码：

//初始化一个 cURL 对象
$curl = curl_init();
//设置你需要抓取的URL
curl_setopt($curl, CURLOPT_URL, " http://www.php.cn");
//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($curl, CURLOPT_RETURNTRANSFER, 0);
//运行cURL，请求网页
$data = curl_exec($curl);
//关闭URL请求
curl_close($curl);
$user = "admin";
$pass = "admin100";
$curlPost = "user=$user&pass=$pass";
$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, " http://localhost/curl/login.php ");
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 0);
curl_setopt($ch, CURLOPT_POST, 1);
curl_setopt($ch, CURLOPT_POSTFIELDS, $curlPost);
$data = curl_exec($ch);
curl_close($ch);
?>
if($_POST['user']=="admin"){
 echo "";
}else{
 echo "";
}
//print_r($_POST);
?>

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