How to write the complete code of a simple python crawler

Complete code steps for a simple python crawler: 1. Import the required libraries; 2. Specify the URL of the target web page; 3. Send a request to the target web page and obtain the HTML content of the page; 4. Use "BeautifulSoup" to parse HTML content; 5. Use CSS selectors or XPath to locate the data that needs to be crawled according to the structure and needs of the target web page; 6. Process the acquired data; 7. Save the data to a file or database; 8. Exception handling and logging

The operating environment of this tutorial: Windows 10 system, python version 3.11.2, dell g3 computer.

To write a simple Python crawler complete code, you can follow the following steps:

1. Import the required libraries:

import requests
from bs4 import BeautifulSoup

2. Specify the target web page URL:

url = "https://example.com"

3. Send a request to the target web page and obtain the HTML content of the page:

response = requests.get(url)
html_content = response.content

4. Use BeautifulSoup to parse the HTML content:

soup = BeautifulSoup(html_content, 'html.parser')

5. According to the target web page The structure and needs, use CSS selectors or XPath to locate the data that needs to be crawled:

data = soup.select('css选择器')

6. Process the acquired data:

for item in data:
# 进行数据处理或存储等操作

7. Save the data to a file or database:

# 保存数据到文件
with open('data.txt', 'w') as file:
for item in data:
file.write(item.text + '\n')
# 保存数据到数据库
import sqlite3
conn = sqlite3.connect('data.db')
cursor = conn.cursor()
for item in data:
cursor.execute("INSERT INTO table_name (column_name) VALUES (?)", (item.text,))
conn.commit()
conn.close()

8. Exception handling and logging:

try:
# 执行爬取代码
except Exception as e:
# 处理异常
print("出现异常：" + str(e))
# 记录日志
with open('log.txt', 'a') as file:
file.write("出现异常：" + str(e) + '\n')

The above is a complete code example of a simple Python crawler, which you can modify and extend according to actual needs. Of course, this is just a basic framework, and more processing may be involved in practice, such as anti-crawler measures, multi-threading or asynchronous processing, etc.

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