在进行国内网站数据爬取时，我们常常会遇到一些限制，例如频繁的IP封禁或访问速度过慢等问题。为了解决这些困扰，我们可以使用代理IP来提升爬虫效率。本文将带领大家一起探讨如何选择和配置代理IP，以帮助我们更好地完成爬虫任务。

I. Proxy IP selection

1. The dilemma of free proxy IPs

Many of you may think of using a free proxy IP at first, after all, not spending money is vital for us, after all, there are still a lot of delicious food waiting for us to taste! However, free proxy IPs are often of poor quality, unstable and may even be malicious. The providers of these free proxy IPs often profit in a number of ways and may tamper with the content of the page while you are requesting it, resulting in inaccurate or even attacked data that you crawl.

2. Advantages of paid proxy IP

In contrast, paid proxy IPs are more reliable and stable. Although there will be a certain cost, but it is worth spending. It's like our stingy shopping guide sister recommended a cheap goods to you, you hard to buy back to use the quality of that is called a poor, it is better not to buy it! Therefore, when choosing a proxy IP, or do not be stingy, or to spend a little more effort to find a high-quality paid proxy IP.

II. Proxy IP Configuration

1. Proxy IP settings

Before using proxy IP, we need to configure it accordingly. There are two main ways to configure the proxy IP: using the system proxy or through code.

The use of a system agent generally applies in the case of a global agent, which can be set up by following the steps below:

import requests

proxies = {
'http': 'http://127.0.0.1:1080',
'https': 'https://127.0.0.1:1080',
}

response = requests.get(url, proxies=proxies)
``

# And if we only need proxies for specific requests, we can do it in code, example below:

import requests

proxy = 'http://127.0.0.1:1080'

response = requests.get(url, proxies={'http': proxy, 'https': proxy})

2. Proxy IP rotation

In order to increase the efficiency of the crawler, we also need to rotate proxy IPs regularly. After all, we don't just want to crawl data happily, we also want to fetch them efficiently. Using the same proxy IP over and over again is easily recognized by the target website, so we need to rotate proxy IPs manually or automatically.

Manual rotation of proxy IPs can be configured to suit your situation, for example, setting a timer to switch proxy IPs after a certain amount of time has been reached. if you need to rotate them automatically, you can refer to the following code:

import requests
from itertools import cycle

proxies = [
'http://127.0.0.1:1080',
'http://127.0.0.2:1080', 'http://127.0.0.2:1080', 'http://127.0.0.2:1080'
'http://127.0.0.3:1080'.
]

proxy_pool = cycle(proxies)

response = requests.get(url, proxies={'http': next(proxy_pool)})

With the above code, we put multiple proxy IPs into a pool of proxies and then use the `cycle` function to make them recycle. In this way, the next proxy IP is used for each request to rotate the proxy IPs.

3. Proxy IP quality testing

Though we use paid proxy IPs, they can be of poor quality. Therefore, there are ways in which we can check the quality of proxy IPs before using them.

An easy way to do this is to send a request and check the status code returned. If the returned status code is 200, the proxy IP is working properly; if the returned status code is 403 or 502, etc., it may indicate that the proxy IP is invalid or unstable.

import requests

def check_proxy(proxy)::
try.
response = requests.get(url, proxies={'http': proxy, 'https': proxy}, timeout=5)
if response.status_code == 200: if response.status_code == 200: if response.status_code == 200
return True
except.
pass
return False

valid_proxies = [proxy for proxy in proxies if check_proxy(proxy)]

With the above code, we define a `check_proxy` function that sends a simple request to check the validity of the proxy IP and then saves the valid proxy IP.

通过选择高质量的付费代理IP，并进行适当的配置和轮换，我们可以大大提高国内爬虫的效率。记得，当你在需求省钱的时候，选择免费代理IP可能会导致任务失败或受到攻击。最后，希望大家在使用代理IP的过程中能够保持合法合规，以免引起不必要的麻烦。