Method for automatically controlling browsers to implement crawlers based on PHP

With the continuous development of the Internet, the value of data is becoming higher and higher. Crawler technology is a way to obtain web page data. Through crawlers, you can obtain information on other people's websites, which is very useful. In actual development, we often need to use automated tools to crawl web page information. This article will introduce how to automatically control browsers to implement crawlers based on PHP.

1. HTTP protocol

Before implementing the crawler, we need to understand the HTTP protocol. HTTP is an application layer protocol based on the TCP/IP protocol. It is a transport protocol used to transmit hypertext from a World Wide Web server to a local browser. When we visit a website, we actually send an HTTP request to the website's server, and the server returns an HTTP response containing the requested information.

2. PHP crawler framework

When using PHP for crawler development, we first need to choose a suitable PHP crawler framework. The current mainstream PHP crawler frameworks include Goutte, Symfony official components, Simple HTML DOM, etc. These frameworks all provide encapsulation of HTTP requests and HTML parsing.

In this article we will use Symfony official components to implement the crawler.

3. Chrome Headless

In the process of automatically controlling the crawler browser, we need to use Chrome Headless. Chrome Headless is an API designed for headless Chrome that supports all Chrome developer tools features, including remote debugging and local debugging.

4. Install Chrome Headless

First we need to install Chrome Headless on the server. You can use the following command:

curl https://intoli.com/install-google-chrome.sh | bash
sudo apt-get install -yq unzip xvfb libxi6 libgconf-2-4
sudo apt-get install -y xfonts-100dpi xfonts-75dpi xfonts-scalable xfonts-cyrillic

The above command will download and install Chrome Headless and install some dependencies.

5. Implementing crawlers based on Symfony components

After installing Chrome Headless, we can start using Symfony components to implement crawlers. Below we will use an example to demonstrate how to automatically control the browser to implement a crawler based on PHP.

use SymfonyComponentBrowserKitHttpBrowser;
use SymfonyComponentHttpClientHttpClient;
use SymfonyComponentBrowserKitRequest;

// 创建一个 HttpBrowser 实例
$browser = new HttpBrowser(HttpClient::create());

// 设置 Chrome Headless 的命令路径
$browser->setClient(new SymfonyComponentHttpClientCurlHttpClient(), [
    'bindto' => '0.0.0.0',
    'timeout' => 5,
    'headers' => [],
]);

// 发送 GET 请求
$response = $browser->request(
    Request::METHOD_GET,
    'https://www.baidu.com'
);

// 输出响应内容
echo $response->getContent();

The above code creates an HttpBrowser instance and sets the command path for Chrome Headless. We sent a GET request through the request method of HttpBrowser and output the response content.

Through the above examples, we can find that it is very simple to implement a crawler based on PHP automatic control browser. We only need to use the PHP crawler framework and Chrome Headless to easily realize automated crawler control of the browser. This method can not only greatly improve the efficiency of crawlers, but also solve some anti-crawler methods (such as verification codes) to achieve more accurate web page information capture.

In general, through the introduction of this article, we can understand the method of automatically controlling browsers to implement crawlers based on PHP. As the Internet continues to develop, crawler technology will become more and more important. Therefore, I hope this article can be helpful to everyone and provide more inspiration and ideas for everyone's crawler development.

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