requests入门大全

1. Introduction

When it comes to making HTTP requests in Python, the requests library is widely regarded as one of the best choices. It provides a simple and intuitive interface for interacting with HTTP resources, making it easy to send requests, handle responses, and manage sessions. This article serves as a comprehensive guide for beginners looking to get started with the requests library.

2. Installation

To begin using the requests library, you first need to install it. Thankfully, installation is quite simple using pip, the package installer for Python.

pip install requests

This command will install the latest version of the requests library along with any necessary dependencies.

3. Sending a GET Request

Now that you have the requests library installed, you can start making HTTP requests. The most basic type of request is the GET request, which retrieves information from a server.

import requests

response = requests.get('https://api.example.com/data')

Here, we are using the requests.get() method to send a GET request to the specified URL. The response from the server is stored in the response variable.

3.1 Handling the Response

Once you have sent a request and received a response, you can access various properties of the response object.

print(response.status_code)  # Prints the status code of the response

print(response.text)  # Prints the content of the response
print(response.json())  # Parses the response as JSON and returns a dictionary

The status_code attribute gives you the HTTP status code of the response, which indicates whether the request was successful or encountered an error. The text attribute contains the content of the response as a string, while the json() method parses the response as JSON and returns a dictionary.

4. Customizing Requests

The requests library allows you to customize your HTTP requests in various ways.

4.1 Headers

You can specify custom headers for your requests using the headers parameter.

headers = {'User-Agent': 'Mozilla/5.0'}

response = requests.get('https://api.example.com/data', headers=headers)

Here, we are setting the User-Agent header to mimic a request coming from the Mozilla Firefox browser.

4.2 Query Parameters

You can pass query parameters in the URL using the params parameter.

params = {'key': 'value'}

response = requests.get('https://api.example.com/data', params=params)

This will append the query parameters to the URL, making it easy to specify filters, search terms, or any other parameters required by the server.

5. Session Management

The requests library supports session management, allowing you to persist certain parameters across multiple requests.

session = requests.Session()

response = session.get('https://api.example.com/login', params={'username': 'john', 'password': 'secret'})
response = session.get('https://api.example.com/data')

By using the Session object, you can maintain cookies, headers, and other parameters across multiple requests.

6. Conclusion

The requests library is an invaluable tool for working with HTTP resources in Python. It provides a simple and intuitive interface while offering powerful customization options. Whether you are making simple GET requests or handling complex scenarios, the requests library has got you covered. Hopefully, this guide has provided you with a solid foundation to start exploring the requests library and all its capabilities.