Crawler development and implementation: PHP and Selenium practical strategy

With the continuous development of the Internet, more and more data need to be obtained from web pages. Unlike manual browsing of web pages to read information, crawler technology can automatically obtain data. In crawler technology, Selenium is an automated testing tool that can simulate users operating on web pages and obtain data on web pages. This article will introduce how to use PHP and Selenium to implement crawler functions.

What is Selenium?

Selenium is an automated testing tool that can simulate all user operations on a web page, such as input, click, scroll, etc., and can also obtain data on the web page. Selenium can support multiple browsers, such as Chrome, Firefox, Edge, etc., and can use different languages ​​to write test scripts. In crawler technology, Selenium can simulate users operating web pages and crawl data from web pages.

Preparation before crawler development

Before using Selenium for crawler development, you need to install a browser driver that supports Selenium, such as Chrome's browser driver. You can download the latest version of the Chrome driver from the Selenium official website and install it.

Next, you need to install PHP and related extensions locally, such as php-webdriver. You can use Composer to install it, as shown below:

composer require php-webdriver/webdriver

Simple example: Get the title of the web page

The first step in using Selenium for crawler development is to open the web page that needs to crawl data. Suppose we need to get the title of a web page, we can follow the following steps:

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

use FacebookWebDriverRemoteDesiredCapabilities;
use FacebookWebDriverRemoteRemoteWebDriver;

// 启动Chrome浏览器
$capabilities = DesiredCapabilities::chrome();
$driver = RemoteWebDriver::create('http://localhost:9515', $capabilities);

// 打开需要抓取数据的网页
$driver->get('https://www.example.com');

// 获取网页标题
$title = $driver->getTitle();
echo $title;

// 关闭浏览器
$driver->quit();

Code analysis:

1. First, use require_once to introduce the required class library document.
2. Use DesiredCapabilitiesCreate a browser driver and specify the Chrome browser.
3. Use RemoteWebDriver::createLaunch a Chrome browser and connect to the Selenium server.
4. Use the get method to open the web page that needs to capture data.
5. Use the getTitle method to get the title of the web page.
6. Output the web page title.
7. Finally use the quit method to close the Chrome browser.

Simple example: log in to the web page and crawl the data

In actual crawler development, we may need to log in to the web page to obtain the required data. The following is a sample code for logging into a website and grabbing data:

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

use FacebookWebDriverRemoteDesiredCapabilities;
use FacebookWebDriverRemoteRemoteWebDriver;
use FacebookWebDriverWebDriverBy;

// 启动Chrome浏览器
$capabilities = DesiredCapabilities::chrome();
$driver = RemoteWebDriver::create('http://localhost:9515', $capabilities);

// 打开登录页面
$driver->get('https://www.example.com/login');

// 输入账号密码并登录
$accountInput = $driver->findElement(WebDriverBy::id('account'));
$passwordInput = $driver->findElement(WebDriverBy::id('password'));
$submitButton = $driver->findElement(WebDriverBy::id('submit'));
$accountInput->sendKeys('your_username');
$passwordInput->sendKeys('your_password');
$submitButton->click();

// 等待登录成功并打开需要抓取数据的页面
$driver->wait(10)->until(
    WebDriverExpectedCondition::titleContains('Homepage')
);
$driver->get('https://www.example.com/data');

// 获取数据
$data = $driver->findElement(WebDriverBy::cssSelector('.data'))->getText();
echo $data;

// 关闭浏览器
$driver->quit();

Code analysis:

1. First, use require_once to introduce the required class library files.
2. Use DesiredCapabilitiesCreate a browser driver and specify the Chrome browser.
3. Use RemoteWebDriver::createLaunch a Chrome browser and connect to the Selenium server.
4. Use the get method to open the page that requires login.
5. Use the findElement method to obtain the corresponding WebElement object through the id of the input element of the account and password, and call the sendKeys method to pass in the account password for input.
6. Use the findElement method to obtain the corresponding WebElement object through the id of the submit button, and call the click method to click and complete the login operation.
7. Use the wait method to wait until the title after the page jumps contains Homepage.
8. Use the get method to open the page where data needs to be captured.
9. Use the findElement method to obtain the corresponding WebElement object through the CSS selector, and use the getText method to obtain the text content.
10. Output the obtained data.
11. Finally use the quit method to close the Chrome browser.

The above is a sample code. In actual development, it needs to be modified according to the page structure and element ID of the specific website.

Summary

This article introduces how to use PHP and Selenium for crawler development, and provides example demonstrations from two aspects: obtaining web page titles and logging in to crawl data. As an automated testing tool, Selenium can simulate user operations on web pages, facilitate the capture of data in web pages, and can also be used in other automated testing scenarios. By mastering the use of Selenium, you can improve your technical level and work efficiency.

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