Create a fast, efficient web crawler: PHP and Selenium example

With the continuous development of the Internet, data crawling has become an essential skill for many people. Web crawlers are one of the important tools for data crawling.

Web crawlers can automatically access websites, obtain content, analyze pages and extract required data. Among them, Selenium is an excellent network automation testing tool that can simulate real user operations and is very helpful for building web crawlers.

This article will introduce how to use PHP and Selenium to create a fast and efficient web crawler. Before doing this, we need to understand some basic knowledge.

1. Installation environment

Before starting, you need to install PHP and Selenium.

1. Install PHP

In Windows environment, you can download and install the XAMPP or WAMP software package, and Mac users can install the MAMP software package.

In Linux environment, you can install PHP through the command line. For example, on Ubuntu system, you can install it through the following command:

sudo apt-get install php7.0

It should be noted that when installing PHP, you need to confirm that some necessary extensions have been installed, such as: php-curl. You can confirm whether the extension has been installed by running the following command:

php -m | grep curl

If there is no curl extension, you need to install it manually.

2. Install Selenium

Before installing Selenium, you need to install the Java Runtime Environment (JRE).

Selenium Server Standalone Edition can be downloaded from Selenium’s official website (https://www.selenium.dev/downloads/).

You can use the following command to start the Selenium server:

java -jar selenium-server-standalone-3.xx.x.jar

2. Use Selenium and PHP to build a network Crawler

Before you start building a web crawler, you need to understand some basic concepts:

1. WebDriver

WebDriver is a core component in Selenium that can Used to control browser behavior. Using WebDriver, we can automatically open and close the browser and simulate the user's operation behavior.

2. Locator

Locator is used to locate elements on an HTML page. Commonly used positioning methods in Selenium include id, name, class, tagname, css, xpath, etc.

3. Action

Action refers to certain user actions in the browser, such as clicking, entering text, mouse hovering, etc.

In this example, we will use the Selenium WebDriver automated testing tool and the PHP programming language to create a web crawler. Taking Baidu (https://www.baidu.com) as an example, we will search for keywords and crawl the links of the search results.

First, you need to use Composer to install Selenium WebDriver and PHP WebDriver in the PHP project.

1. Configuring Composer

Before creating a PHP project, you need to install Composer (https://getcomposer.org/) and create a new PHP project through the command line .

In the project folder, you can install Selenium WebDriver and PHP WebDriver using the following command:

composer require facebook/webdriver

2. Writing code

Create a new file crawl.php in the project folder, edit the code as follows:

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

use FacebookWebDriverRemoteDesiredCapabilities;
use FacebookWebDriverRemoteRemoteWebDriver;
use FacebookWebDriverWebDriverBy;
use FacebookWebDriverWebDriverKeys;

// 设置WebDriver
$host = 'http://localhost:4444/wd/hub';
$capabilities = DesiredCapabilities::chrome();
$driver = RemoteWebDriver::create($host, $capabilities, 5000);

// 打开百度
$driver->get('https://www.baidu.com');

// 搜索关键字
$search_box = $driver->findElement(WebDriverBy::id('kw'));
$search_box->sendKeys('Selenium');
$search_box->sendKeys(WebDriverKeys::ENTER);

// 等待页面加载完成
sleep(5);

// 抓取搜索结果链接
$elements = $driver->findElements(WebDriverBy::xpath('//div/h3/a'));
foreach ($elements as $element) {
    echo $element->getAttribute('href')."
";
}

// 关闭浏览器
$driver->quit();
?>

First, we need to set up the webdriver, including the browser used (Chrome browser is used here) and the WebDriver service the address of.

Next, use WebDriver to open Baidu homepage. We will find the Baidu search box by id, enter the keyword Selenium and press Enter to submit the search. After that, wait for the page to load and get links to all search results.

Finally, close the browser.

3. Run the code

Execute the following command in the command line to run crawl.php and crawl the search result link:

php crawl .php

3. Summary

Through the introduction of this article, you can learn how to use PHP and Selenium to build a simple web crawler. Selenium WebDriver can be used to simulate user operations, thereby achieving better web crawling results. In practical applications, we can adopt different positioning methods and customize operation behaviors as needed to achieve more accurate and efficient data crawling.

Note: This example is for learning reference only and is prohibited for illegal purposes.

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