Starting from scratch: How to build a web data crawler using PHP and Selenium

With the development of the Internet, network data crawling has increasingly become the focus of attention. Web data crawlers can collect a large amount of useful data from the Internet to support enterprises, academic research, and personal analysis. This article will introduce the methods and steps for building a web data crawler using PHP and Selenium.

1. What is a web data crawler?

Web data crawlers refer to automated programs that collect data from designated websites on the Internet. Web data crawlers are implemented using different technologies and tools, the most common of which are the use of programming languages ​​and automated testing tools. Web data crawlers can store the collected data in local or remote databases for further processing and analysis.

2. Introduction to Selenium

Selenium is an automated testing tool that can simulate user operations on the browser and collect data from web applications. Because it simulates user operations, JavaScript and AJAX can be executed in the browser to obtain complete dynamic web page data. Selenium provides a variety of programming language interfaces, including PHP, which can easily write web crawler programs.

3. Install PHP and Selenium

Before we start using PHP and Selenium to build a web data crawler, we need to install PHP and Selenium first. The latest version of PHP can be downloaded from the official website (https://www.php.net/downloads.php), and the Selenium PHP client can be downloaded from the official website (https://php-webdriver.github.io/php-webdriver/latest/ ) or download from Github.

The installation process is very simple: download the PHP installation package corresponding to the operating system from the official website, and then install it according to the corresponding installation tutorial. After downloading the Selenium PHP client, unzip it locally and use Composer or manually install the extension into PHP.

4. Use Selenium to build a web data crawler

Before introducing how to use Selenium to build a web data crawler, you need to understand some concepts first.

4.1 Browser driver

Selenium needs to interact with the browser to achieve automation. In order to use Selenium, we need to download and install the driver corresponding to the target browser. For example, if you want to use the Chrome browser, you need to install the Chrome driver so that Selenium intercepts and interprets user actions and sends them to the browser.

4.2 Element positioning

The most basic operation of collecting data is to find the location of the target data. Selenium provides a variety of element positioning methods, including tag name, ID, class name, link text, CSS selector and XPath selector, etc.

Next we will introduce how to use Selenium-based PHP client to build a web data crawler.

4.3 Code Implementation

Next, we will show how to build a web data crawler using PHP and Selenium. In this example, we will visit https://www.baidu.com, search for "PHP and selenium" and output the search results to the terminal.

<?php
require_once('vendor/autoload.php');

use FacebookWebDriverRemoteRemoteWebDriver;
use FacebookWebDriverWebDriverBy;

// 设置驱动路径和浏览器驱动
$driverPath = 'path/to/chromedriver';
$chromeOptions = array('--no-sandbox');
$driver = RemoteWebDriver::create($driverPath, array('chromeOptions' => $chromeOptions));

// 打开https://www.baidu.com/
$driver->get('https://www.baidu.com/');

// 在搜索框中输入“PHP and selenium”
$searchBar = $driver->findElement(WebDriverBy::id('kw'));
$searchBar->sendKeys('PHP and selenium');

// 点击搜索按钮
$searchButton = $driver->findElement(WebDriverBy::id('su'));
$searchButton->click();

// 等待页面加载
sleep(3);

// 获取搜索结果并输出到终端
$searchResult = $driver->findElements(WebDriverBy::className('c-container'));
foreach ($searchResult as $result) {
    echo $result->getText() . "
";
}

// 关闭浏览器窗口
$driver->close();
?>

Before executing the code, the driver path needs to be set to the correct Chrome driver path. Then execute the above code.

Summary

This article briefly introduces how to use PHP and Selenium to build a web data crawler. By using Selenium, we can access and obtain dynamic web page data, which provides more opportunities for data mining. Of course, the use of web crawlers requires attention to legality and ethical issues, and relevant laws, regulations and ethical principles must be observed when using them.

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