python 抓取网页链接_从Python中的网页抓取链接

python 抓取网页链接

Prerequisite:

先决条件：

Urllib3: It is a powerful, sanity-friendly HTTP client for Python with having many features like thread safety, client-side SSL/TSL verification, connection pooling, file uploading with multipart encoding, etc.
Urllib3 ：这是一个功能强大，对环境友好的Python HTTP客户端，具有许多功能，例如线程安全，客户端SSL / TSL验证，连接池，使用多部分编码的文件上传等。

Installing urllib3:
安装urllib3：
```
    $ pip install urllib3
```
BeautifulSoup: It is a Python library that is used to scrape/get information from the webpages, XML files i.e. for pulling data out of HTML and XML files.
BeautifulSoup ：这是一个Python库，用于从网页，XML文件中抓取/获取信息，即从HTML和XML文件中提取数据。

Installing BeautifulSoup:
安装BeautifulSoup：
```
    $ pip install beautifulsoup4
```

Commands Used:

使用的命令：

html= urllib.request.urlopen(url).read(): Opens the URL and reads the whole blob with newlines at the end and it all comes into one big string.

html = urllib.request.urlopen(url).read() ：打开URL并以换行符结尾读取整个blob，所有这些都变成一个大字符串。

soup= BeautifulSoup(html,'html.parser'): Using BeautifulSoup to parse the string BeautifulSoup converts the string and it just takes the whole file and uses the HTML parser, and we get back an object.

soup = BeautifulSoup(html，'html.parser') ：使用BeautifulSoup解析字符串BeautifulSoup转换该字符串，它只获取整个文件并使用HTML解析器，然后返回一个对象。

tags= soup('a'): To get the list of all the anchor tags.

tags =汤('a') ：获取所有锚标签的列表。

tag.get('href',None): Extract and get the data from the href.

tag.get('href'，None) ：从href中提取并获取数据。

网页链接的Python程序 (Python program to Links from a Webpage)

# import statements
import urllib.request, urllib.parse, urllib.error
from bs4 import BeautifulSoup
# Get links
# URL of a WebPage
url = input("Enter URL: ") 
# Open the URL and read the whole page
html = urllib.request.urlopen(url).read()
# Parse the string
soup = BeautifulSoup(html, 'html.parser')
# Retrieve all of the anchor tags
# Returns a list of all the links
tags = soup('a')
#Prints all the links in the list tags
for tag in tags: 
# Get the data from href key
print(tag.get('href', None), end = "\n")

Output:

输出：

Enter URL: https://www.google.com/
https://www.google.com/imghp?hl=en&tab=wi
https://maps.google.com/maps?hl=en&tab=wl
https://play.google.com/?hl=en&tab=w8
https://www.youtube.com/?gl=US&tab=w1
https://news.google.com/nwshp?hl=en&tab=wn
https://mail.google.com/mail/?tab=wmhttps://drive.google.com/?tab=wo
https://www.google.com/intl/en/about/products?tab=wh
http://www.google.com/history/optout?hl=en
/preferences?hl=en
https://accounts.google.com/ServiceLogin?hl=en&passive=true
&continue=https://www.google.com/
/advanced_search?hl=en&authuser=0
/intl/en/ads/
/services/
/intl/en/about.html
/intl/en/policies/privacy/
/intl/en/policies/terms/