How to use PHP and Selenium to get through the last mile of web crawler development

A web crawler is an automated program that helps users quickly collect data by accessing web pages on the Internet and extracting the required information. For the needs and analysis of large amounts of data, crawlers have become one of the key means to meet these needs. However, efficient implementation of crawlers is not easy. Especially when encountering difficulties such as anti-crawler mechanisms, JavaScript, and dynamic rendering, you need to use some tools to achieve it.

Among them, Selenium is a commonly used tool that can simulate user operations in the browser to operate web pages and extract data. PHP is a classic development language with the advantages of strong scalability, easy maintenance and low start-up cost. This article will introduce in detail how to use PHP and Selenium to get through the "last mile" of web crawler development.

Preparation work

Before using PHP and Selenium to develop web crawlers, you need to do some preparation work.

1. Install PHP and Selenium

Ensure that PHP and Selenium have been installed in the system and can run correctly. If it is not installed yet, you can install it in the following ways.

• Install PHP: You can download the latest PHP version from the official website (https://www.php.net/downloads.php) and install it according to the installation program prompts.
• Install Selenium: You can download the latest version of Selenium WebDriver from the official website (https://www.selenium.dev/downloads/).

2. Installing and configuring browser drivers

Selenium WebDriver can control a variety of browsers, but the corresponding browser driver needs to be installed. Therefore, when using Selenium, you need to install and configure the browser driver. This article uses the Chrome browser as an example. The installation methods for other browsers are similar.

• Download Chrome driver: You can download the corresponding Chrome driver version from the official website (https://sites.google.com/a/chromium.org/chromedriver/downloads).
• Configure the Chrome driver path: Unzip the downloaded Chrome driver into a folder, and add the full path to the chromedriver executable file in the folder to the system environment variable.

After installing the above environmental dependencies, you can start using PHP and Selenium to develop web crawlers.

Use PHP and Selenium for web crawler development

1. Create a PHP file

First, create a PHP file named test.php, and Import Selenium's PHP library file, that is, selenium-php library:

require_once('vendor/autoload.php');

2. Start a webdriver instance

WebDriver is an important part of Selenium. It is used to drive the browser and simulate user behavior. Therefore, before using Selenium to crawl the website, you need to start a WebDriver instance in the PHP file and specify the browser type and driver path. This article takes the Chrome browser as an example:

use FacebookWebDriverRemoteDesiredCapabilities;
use FacebookWebDriverRemoteRemoteWebDriver;

$host = 'http://localhost:9515/';
$capabilities = DesiredCapabilities ::chrome();
$webdriver = RemoteWebDriver::create($host, $capabilities);

3. Access the target web page and obtain data

At startup After creating a WebDriver instance, you can use it to control the browser and access the target web page. This article takes accessing the Baidu search page as an example:

$webdriver->get("http://www.baidu.com");

After accessing the web page, it can be provided through Selenium API to obtain web page data. For example, get the title in the web page:

$title = $webdriver->getTitle();

4. Perform simulated user operation

Selenium An important function is to simulate user operations in the browser, including clicks, inputs, scrolling and other operations. Below, take entering a keyword in the search box and triggering the search button as an example:

use FacebookWebDriverWebDriverBy;
use FacebookWebDriverWebDriverKeys;

$input = $webdriver->findElement(WebDriverBy: :name('wd'));
$input->sendKeys('selenium');
$input->sendKeys(WebDriverKeys::ENTER);

5. Close WebDriver instance

After completing the website crawling task, you need to close the WebDriver instance and release resources.

$webdriver->quit();

Use PHP and Selenium together for web crawler development, which can easily control the browser and simulate user behavior. Especially when encountering complex anti-crawler mechanisms and dynamic rendering, using the combination of PHP and Selenium can greatly improve development efficiency. However, there are also some safety and legal issues that need to be paid attention to to avoid violating relevant regulations.

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