Java Web Crawler: Automated Capture Programs

First, why is your crawler always pulled by the site?

Brothers who have engaged in web crawling must have encountered this situation: yesterday is a good program, today suddenly 403 error, or is to return a bunch of CAPTCHA. This matter is franklyYour real IP was found by the websiteIt is not a good idea to have an intelligent wind control system. Now a little bit of the scale of the site are equipped with intelligent wind control system, the same IP continuous access dozens of times, minutes to you off the small black house.

Last week a guy who does e-commerce price comparison came to me and complained that the collection program they wrote in Java was running and broke down. I asked him to send the log to see, good guy, clear all Amazon's robot verification page. This situation does not need to think much, certainly did not do a good job of IP camouflage.

Second, hand to teach you to use Java with proxy

Here to show the guys a basic version of the proxy configuration, take the most common HttpClient:

// Remember to add the httpclient dependency in pom.xml
CloseableHttpClient httpClient = HttpClients.custom()
    .setProxy(new HttpHost("proxy.ipipgo.com", 9000)) // use ipipgo's proxy server here
    .build();
HttpGet request = new HttpGet("https://目标网站.com");
try (CloseableHttpResponse response = httpClient.execute(request)) {
    // Process the response data...
}

Notice in the code theproxy.ipipgo.comThis address, this is ipipgo provides dynamic proxy entrance. Their proxy has the advantage of automatically switching IPs for each request, which is much more trouble-free than tossing the proxy pool yourself.

Third, the advanced play of proxy IP

It's not enough to know the basics, here are a few practical tips to share:

1. Random request header settings

Don't let the site see that you are a robot! It is recommended to randomly change User-Agent for each request, you can prepare a txt file to store dozens of browser logos.

2. Intelligent delay strategy

Don't be stupid and use fixed time intervals, get a random delay (between 0.5-3 seconds) to simulate the rhythm of a real person's operation. This trick has been measured to increase survival rates by more than 40%.

IV. Clearance of QA FAQs

Q: Why do I still get banned after using a proxy?
A: Check three things: ① proxy IP quality ② request frequency is too high ③ there is no processing cookies

Q: How do I choose a package for ipipgo?
A: For individual developersBasic 500IP/dayEnough, enterprise-level business straight upexclusive IP poolThe need for high anonymity in the selection ofEnterprise Customized Edition

Q: What about proxy request timeout?
A: first adjust the timeout time to 15 seconds, if it continues to appear suggest contacting ipipgo customer service to change the access node

V. Guide to avoiding pits (lessons learned through blood and tears)

Last year, I stepped into a big pit when I helped my friend to do the ticket monitoring system: I used a free proxy at that time to get a cheaper price, and the result was that I dropped the chain at the critical moment. Later, I switched to ipipgo'sCommercial level agentsNot only is the success rate stable at over 98%, but there's also an unexpected bonus - it was discovered that their IP segments can actually bypass specific geographic restrictions on certain websites (this counts as a hidden benefit).

One last word of advice: don't save money on proxy IPs! A good proxy service can make you lose less hair, and the time saved to write a few more crawlers doesn't smell good? Brothers who need to test can go to the official website of ipipgo to get theFree Trial PackThe newcomers also get 50 API calls for signing up, which is tested and valid.