As crawlers become the mainstream method of accessing Internet data, more and more websites have adopted anti-crawler strategies to deal with crawler visits. It is vital for a crawler to understand how to respond to a website's anti-crawler strategy. In the face of website anti-crawling measures, you can take the following measures to deal with:
1, processing captcha: Many websites will require users to enter a captCHA to verify whether they are robots when crawlers visit frequently. For the verification code, you can take the following solutions:
Manually enter the verification code: Download the verification code to a local PC and enter the verification code manually. This approach is costly and cannot be fully automated, requiring human intervention.
Image recognition verification code: automatically identify the verification code through image recognition technology and fill in the verification. Although the effect is good, there are still some difficulties for complex verification codes.
Access to automatic coding platform: Use a third-party automatic coding platform to help process verification codes for automated verification.
2. Multi-account access: In the face of the anti-crawling strategy of the website, in view of the operation frequency limit of the same user within a unit time, we can adopt the multi-account access strategy, and effectively avoid the restrictions of the anti-crawling strategy by testing the single-user crawling threshold, switching accounts and using distributed crawling technology to ensure the efficient crawler work.
Test the single-user crawl threshold: Before starting the crawl, we need to test the maximum frequency that a single account can access in a unit of time, that is, the site's limit on the frequency of user visits. By constantly trying different frequency visits, observe the response of the website, and find a reasonable crawl frequency threshold. This ensures maximum access to data without exceeding the site's limit of frequent visits.
Account switching: When the access frequency of a single account approaches or reaches the limit set by the website, the user switches to another user account for access in time. This prevents frequent visits by a single account from being identified by the website as bot behavior. By recycling multiple accounts, you can continue to crawl data without violating site restrictions.
Distributed crawler: The use of distributed crawler technology can be accessed on multiple nodes at the same time, reducing the possibility of frequent access to a single point. By decentralizing requests, the frequency of visits between different nodes is relatively low, reducing the risk of being identified as a bot by a website. In addition, distributed crawlers can also improve the efficiency of data acquisition and quickly obtain a large amount of data.
It should be noted that when dealing with the anti-crawling strategy of the website, we should always comply with the rules and policies of the use of the website, and do not carry out malicious crawling and excessive frequent visits. Tactics such as the use of multiple account access are used to reasonably and lawfully collect data, not to circumvent the legitimate restrictions of the website. In the crawler work, maintain respect for the website, reasonable use of data, in order to establish a good network data collection ecology, so that crawler work more smooth and efficient.
3, save Cookies: save the user's login status, simulate the login operation can avoid some tedious verification process. Cookies can be saved in the following ways:
Log in to get Cookies: Log in on the Web and get Cookies, and then bring these Cookies in the crawler for access. However, it should be noted that Cookies may fail after a while and need to be tested and verified continuously.
Update Cookies regularly: Update Cookies regularly within a certain period of time to avoid being identified as a robot because of not updating for a long time.
4, pay attention to the mobile and desktop version: for the desktop version of the website that is difficult to crawl, you can consider giving priority to crawling the mobile website. Mobile websites tend to have a more concise interface and structure, and are less difficult to crawl. At the same time, we should also consider grabbing the data resources of the desktop version and the mobile APP to comprehensively obtain the target data.
By combining the above measures, crawlers can be more flexible in responding to the anti-crawling strategies of different websites, ensuring the smooth operation of crawlers and efficient access to the required data.