Illustration HTTP Reading Notes, Asus Notebook dismounting illustration

Source: Internet
Author: User
Tags 403 forbidden error

Illustration HTTP Reading Notes, Asus Notebook dismounting illustration

Out of interest, I recently learned a Java Web Crawler framework webmagic. In fact, I used a program to automate the download task. For example, if you want to download an image quickly, right-click to download, but it will take some time to download the first 1000 images. But the computer can automate these steps, and you only need to set rules. After a few days of hard work, I was eager to crawl the pages of zhihu, and wanted to download the answers with more than 1000 likes. When the program is started, it receives a message from zhihu's server: 403 Forbidden error and rejects my request. After joining the web crawler QQ group, I learned that I had to pretend to be a "user" to cheat the server. Otherwise, the server rejects similar requests by default.

This made me interested in the network protocol. I entered the address in the browser and press enter to access the page. Essentially, the effect of a line of commands on the computer is not much different, the server does not know this. What it knows is that there is a connection request from Changsha, Hunan. In the past, the server did not know whether the request was sent from a real user or a disguised crawler. As the saying goes, "on the Internet, no one knows whether you are sitting on the opposite side of a human or a dog ". So, from the moment I press enter to the moment I know that the pleasing page is displayed on the browser, what happened behind this? I remember that when I was on the computer network, I also heard about the layer, router forwarding, transmission latency, man-in-the-middle attack, and other TCP/IP protocols. However, I have already returned all of them to my teacher. I just read the graphic HTTP book, which briefly introduced the concepts of protocol layering, HTTP status code, HTTP header information, and WEB security. Most of them are quite understandable, next, I will send the Mind Map of the first seven chapters I have summarized. If you are interested, please download it.


Click here to download the invisible Image

P.s. The first time the webmagic Code was submitted, it was the program that crawled on the page, so excited :).


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