PHP and phpSpider: How to deal with anti-crawler blocking?

PHP and phpSpider: How to deal with the blocking of anti-crawler mechanisms?

Introduction:
With the rapid development of the Internet, the demand for big data is also increasing. As a tool for crawling data, a crawler can automatically extract the required information from web pages. However, due to the existence of crawlers, many websites have adopted various anti-crawler mechanisms, such as verification codes, IP restrictions, account login, etc., in order to protect their own interests. This article will introduce how to use PHP and phpSpider to deal with these blocking mechanisms.

1. Understand the anti-crawler mechanism

1.1 Verification code
Verification code is a commonly used anti-crawler mechanism on websites. It requires users to The user enters the correct verification code to continue accessing the website. Cracking the CAPTCHA is a challenge for crawlers. You can use third-party tools, such as Tesseract OCR, to convert the verification code image into text to automatically recognize the verification code.

1.2 IP restrictions
In order to prevent crawlers from visiting the website too frequently, many websites will restrict based on IP addresses. When an IP address initiates too many requests in a short period of time, the website will consider the IP address to be a crawler and block it. In order to bypass IP restrictions, you can use a proxy server to simulate different user access by switching different IP addresses.

1.3 Account login
Some websites require users to log in before they can view or extract data. This is also a common anti-crawler mechanism. In order to solve this problem, you can use a simulated login method and use a crawler to automatically fill in the user name and password for the login operation. Once logged in successfully, the crawler can access the website like a normal user and obtain the required data.

2. Use phpSpider to deal with the blocking mechanism

phpSpider is an open source crawler framework based on PHP. It provides many powerful functions that can help us deal with various anti-crawler mechanisms.

2.1 Cracking the verification code

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As shown above, by using the relevant libraries of phpSpider and PhantomJs, we Web pages can be saved as screenshots. Next, the screenshot can be passed to an OCR tool to obtain the text content of the verification code. Finally, fill in the text content into the web form to bypass the verification code.

2.2 Simulate login

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As shown above, using the GuzzleHttp library to send a POST request, we can simulate login website. After successful login, continue to access data that requires login.

Summary:
By learning the principles of the anti-crawler mechanism and using the related functions of the phpSpider framework, we can effectively deal with the blocking mechanism of the website, thereby smoothly obtaining the required data. However, we need to be careful to abide by the rules of use of the website and not infringe on the rights of others. Reptiles are a double-edged sword, and only when used reasonably and legally can they maximize their value.

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