1. Web crawlers for web crawling

Web crawlers for web crawling are the most common type. They are tools for obtaining web page data through HTTP requests. This type of crawler usually simulates browser behavior, sends requests and receives corresponding HTML, CSS, JavaScript and other resources, and then parses these resources to extract the required information. In practical applications, web crawlers for web crawling are widely used in search engine crawling, data mining, information collection and other fields.

import requests

from bs4 import BeautifulSoup

url = 'http://example.com'

response = requests.get(url)

soup = BeautifulSoup(response.text, 'html.parser')

# Parse the web page and extract the required information

2. Web crawlers for API interface crawling

In addition to directly crawling web pages, there is another type of web crawler that obtains data by accessing the API interface. Many websites provide API interfaces, allowing developers to obtain data through specific request methods. Web crawlers for API interface crawling do not need to parse HTML. They directly request the API interface and obtain the returned data, and then process and store it. This type of crawler is usually used to obtain structured data from a specific website, such as user information, weather data, stock data, etc.

import requests

url = 'http://api.example.com/data'

params = {'param1': 'value1', 'param2': 'value2'}

response = requests.get(url, params=params)

data = response.json()

# Process the returned data

3. Web crawler with headless browser automation

Web crawler with headless browser automation obtains data by simulating the behavior of the browser. Similar to web crawlers for web crawling, web crawlers with headless browser automation also send HTTP requests and receive corresponding web resources, but they use the browser engine to render pages, execute JavaScript, and obtain dynamically generated content. This type of crawler is usually used to process pages that require JavaScript rendering or scenarios that require user interaction, such as web screenshots, automated testing, etc.

from selenium import webdriver

url = 'http://example.com'

driver = webdriver.Chrome()

driver.get(url)

# Get the rendered page content

I hope that through this article, readers will have a clearer understanding of the three common types of web crawlers and be able to choose the appropriate type of web crawler according to different needs in actual applications.