What built-in PHP functions are useful for web scraping? What are some good resources (web or print) for getting up to speed on web scraping with PHP?
Scraping generally encompasses 3 steps:
To accomplish steps 1 and 2, below is a simple php class which uses Curl to fetch webpages using either GET or POST. After you get the HTML back, you just use Regular Expressions to accomplish step 3 by parsing out the text you'd like to scrape.
For regular expressions, my favorite tutorial site is the following: Regular Expressions Tutorial
My Favorite program for working with RegExs is Regex Buddy. I would advise you to try the demo of that product even if you have no intention of buying it. It is an invaluable tool and will even generate code for your regexs you make in your language of choice (including php).
Usage:
$curl = new Curl(); $html = $curl->get("http://www.google.com");
// now, do your regex work against $html
PHP Class:
<?php
class Curl
{
public $cookieJar = "";
public function __construct($cookieJarFile = 'cookies.txt') {
$this->cookieJar = $cookieJarFile;
}
function setup()
{
$header = array();
$header[0] = "Accept: text/xml,application/xml,application/xhtml+xml,";
$header[0] .= "text/html;q=0.9,text/plain;q=0.8,image/png,*/*;q=0.5";
$header[] = "Cache-Control: max-age=0";
$header[] = "Connection: keep-alive";
$header[] = "Keep-Alive: 300";
$header[] = "Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.7";
$header[] = "Accept-Language: en-us,en;q=0.5";
$header[] = "Pragma: "; // browsers keep this blank.
curl_setopt($this->curl, CURLOPT_USERAGENT, 'Mozilla/5.0 (Windows; U; Windows NT 5.2; en-US; rv:1.8.1.7) Gecko/20070914 Firefox/2.0.0.7');
curl_setopt($this->curl, CURLOPT_HTTPHEADER, $header);
curl_setopt($this->curl,CURLOPT_COOKIEJAR, $this->cookieJar);
curl_setopt($this->curl,CURLOPT_COOKIEFILE, $this->cookieJar);
curl_setopt($this->curl,CURLOPT_AUTOREFERER, true);
curl_setopt($this->curl,CURLOPT_FOLLOWLOCATION, true);
curl_setopt($this->curl,CURLOPT_RETURNTRANSFER, true);
}
function get($url)
{
$this->curl = curl_init($url);
$this->setup();
return $this->request();
}
function getAll($reg,$str)
{
preg_match_all($reg,$str,$matches);
return $matches[1];
}
function postForm($url, $fields, $referer='')
{
$this->curl = curl_init($url);
$this->setup();
curl_setopt($this->curl, CURLOPT_URL, $url);
curl_setopt($this->curl, CURLOPT_POST, 1);
curl_setopt($this->curl, CURLOPT_REFERER, $referer);
curl_setopt($this->curl, CURLOPT_POSTFIELDS, $fields);
return $this->request();
}
function getInfo($info)
{
$info = ($info == 'lasturl') ? curl_getinfo($this->curl, CURLINFO_EFFECTIVE_URL) : curl_getinfo($this->curl, $info);
return $info;
}
function request()
{
return curl_exec($this->curl);
}
}
?>