Is it necessary to learn about reptiles? I think this is a question that doesn’t need to be discussed.
Crawlers are both useful and interesting.
In this era of data king, we want to get the data we need from the huge Internet, crawler is the only choice. Whether it is the past “search engine”, or the popular “data analysis”, it is an essential means to obtain data. After mastering the crawler, you see a lot of “interesting” things! Regardless of your technical orientation, mastering this technology will allow you to explore the booming Internet and collect all kinds of data or documents quickly and easily. There are a lot of applications for crawlers besides being fun, and in fact, many companies require crawlers when hiring.
So to learn web crawler well, you need to master some basic knowledge:
HTTP protocol communication principle (what is the process when we browse the web, how is it constituted?) With the basics of HTML, CSS, and JS (mastering the structure of a web page and locating specific elements from a web page), you’re ready to start crawling. Now crawlers, Python crawlers of course, are the absolute mainstream.
But many of my classmates and friends still have doubts. They often ask me questions like:
Should you learn a crawler first? How do I get to the next level after learning the basics? What’s the point of learning about reptiles? In the latest list of programming languages, Pyhton has overtaken Java as the number one language, and more and more programmers are choosing Python. Some even say that using Python is “programming for the future.” As for the relationship between Python and “crawlers”, of course, it is necessary to master some basic Python knowledge before learning crawlers.
But if you’re just starting out in Python and want to go further, after you’ve mastered the basics of Python, I recommend learning crawlers first, not the other way around. Why?
First, it’s really easy to learn a lot about Python by learning crawlers. Of course, this is probably due to the fact that there are so many great crawlers in the Python world, but there is no doubt that crawlers can hone and improve your Python skills.
Secondly, after mastering crawler technology, you will see many different landscapes. You’ll have a lot of fun crawling data, and trust me, this kind of fun and curiosity will give you a natural love of Python, which will keep you motivated to learn more about Python.
We use Python to develop crawlers. Python’s greatest strength is not the language itself but its large and active developer community and hundreds of millions of third-party toolkits. With these toolkits we can quickly implement one function after another without having to build the wheel ourselves. The more toolkits we have, the more convenient it will be when we write crawlers. In addition, the work target of crawler is “Internet”, so HTTP communication and HTML, CSS, JS skills will be used when writing crawler program.
As developers, code is the best teacher, learning by doing, directly by code, is the way we programmers learn. With a basic Python background, this column will take you from being completely ignorant of crawlers to actually developing and using them at work.
Therefore, WHEN designing this column, I selected several representative topics from many materials, and we developed several different types of crawlers together. In actual production, the data we need generally can not escape the page structure like this:
Special crawler for news feeds — crawler for RSS feed data — Crawler technology — Crawler optimization — Large scale data processing technology — Douban reading crawler — Test-driven design and advanced anti-crawler technology practice mogujie collection — Application example of deep inheritance javascript website slow crawler — Zhihu crawler
Implement one by one I will bring you the page structure, implementation technology of different page crawlers, let everybody through specific code of practice to understand what technology could be used in what circumstances, met the climb the measures we should how to solve, through specific cognition of the specific application built on crawler in understanding the technology behind the theory.
So what about after you write a crawler? Don’t worry, after the preparation of the crawler PROGRAM, I will take you to deploy our crawler program, really let our crawler “grand plan”. About the deployment of the web crawler online, many other tutorials are not explained, but there are indeed many students have doubts about this, do not know how to deploy. While deployment may seem low-tech, it’s something you can’t do without.
Well, I will say no more at this point. As this column unfolds, you’ll discover that web crawlers are not just a simple data-gathering technique, but a key to “full-stack development.”
Through this column course, you will learn:
Master Scrapy framework development learn to crawl to deal with massive data optimize your incremental crawler solve large-scale concurrent crawler project using Docker container technology crawler deployment How much data is hidden on the Internet? What different feelings can it bring to our life and work? Keep your curiosity, from now on, let’s learn crawler, play crawler, use crawler together!
Author: for class official _ network operations center link: www.imooc.com/article/287… Source: MOOC