在Python中处理XML的教程
XML虽然比JSON复杂，在Web中应用也不如以前多了，不过仍有很多地方在用，所以，有必要了解如何操作XML。
DOM vs SAX
操作XML有两种方法：DOM和SAX。DOM会把整个XML读入内存，解析为树，因此占用内存大，解析慢，优点是可以任意遍历树的节点。SAX是流模式，边读边解析，占用内存小，解析快，缺点是我们需要自己处理事件。
正常情况下，优先考虑SAX，因为DOM实在太占内存。
在Python中使用SAX解析XML非常简洁，通常我们关心的事件是start_element，end_element和char_data，准备好这3个函数，然后就可以解析xml了。
举个例子，当SAX解析器读到一个节点时：
<a href="/">python</a>
会产生3个事件：
- start_element事件，在读取时；
- char_data事件，在读取python时；
- end_element事件，在读取时。
用代码实验一下：
from xml.parsers.expat import ParserCreate
class DefaultSaxHandler(object):
def start_element(self, name, attrs):
print('sax:start_element: %s, attrs: %s' % (name, str(attrs)))
def end_element(self, name):
print('sax:end_element: %s' % name)
def char_data(self, text):
print('sax:char_data: %s' % text)
xml = r'''<?xml version="1.0"?>
<ol>
<li><a href="/python">Python</a></li>
<li><a href="/ruby">Ruby</a></li>
</ol>
'''
handler = DefaultSaxHandler()
parser = ParserCreate()
parser.returns_unicode = True
parser.StartElementHandler = handler.start_element
parser.EndElementHandler = handler.end_element
parser.CharacterDataHandler = handler.char_data
parser.Parse(xml)
当设置returns_unicode为True时，返回的所有element名称和char_data都是unicode，处理国际化更方便。
需要注意的是读取一大段字符串时，CharacterDataHandler可能被多次调用，所以需要自己保存起来，在EndElementHandler里面再合并。
除了解析XML外，如何生成XML呢？99%的情况下需要生成的XML结构都是非常简单的，因此，最简单也是最有效的生成XML的方法是拼接字符串：
L = []
L.append(r'<?xml version="1.0"?>')
L.append(r'<root>')
L.append(encode('some & data'))
L.append(r'</root>')
return ''.join(L)
如果要生成复杂的XML呢？建议你不要用XML，改成JSON。
小结
解析XML时，注意找出自己感兴趣的节点，响应事件时，把节点数据保存起来。解析完毕后，就可以处理数据。
练习一下解析Yahoo的XML格式的天气预报，获取当天和最近几天的天气：
http://weather.yahooapis.com/forecastrss?u=c&w=2151330
参数w是城市代码，要查询某个城市代码，可以在weather.yahoo.com搜索城市，浏览器地址栏的URL就包含城市代码。
Hot AI Tools
Undresser.AI Undress
AI-powered app for creating realistic nude photos
AI Clothes Remover
Online AI tool for removing clothes from photos.
Undress AI Tool
Undress images for free
Clothoff.io
AI clothes remover
AI Hentai Generator
Generate AI Hentai for free.
Hot Article
Hot Tools
Notepad++7.3.1
Easy-to-use and free code editor
SublimeText3 Chinese version
Chinese version, very easy to use
Zend Studio 13.0.1
Powerful PHP integrated development environment
Dreamweaver CS6
Visual web development tools
SublimeText3 Mac version
God-level code editing software (SublimeText3)
Hot Topics
How to download deepseek Xiaomi
Feb 19, 2025 pm 05:27 PM
How to download DeepSeek Xiaomi? Search for "DeepSeek" in the Xiaomi App Store. If it is not found, continue to step 2. Identify your needs (search files, data analysis), and find the corresponding tools (such as file managers, data analysis software) that include DeepSeek functions.
How do you ask him deepseek
Feb 19, 2025 pm 04:42 PM
The key to using DeepSeek effectively is to ask questions clearly: express the questions directly and specifically. Provide specific details and background information. For complex inquiries, multiple angles and refute opinions are included. Focus on specific aspects, such as performance bottlenecks in code. Keep a critical thinking about the answers you get and make judgments based on your expertise.
How to search deepseek
Feb 19, 2025 pm 05:18 PM
Just use the search function that comes with DeepSeek. Its powerful semantic analysis algorithm can accurately understand the search intention and provide relevant information. However, for searches that are unpopular, latest information or problems that need to be considered, it is necessary to adjust keywords or use more specific descriptions, combine them with other real-time information sources, and understand that DeepSeek is just a tool that requires active, clear and refined search strategies.
How to program deepseek
Feb 19, 2025 pm 05:36 PM
DeepSeek is not a programming language, but a deep search concept. Implementing DeepSeek requires selection based on existing languages. For different application scenarios, it is necessary to choose the appropriate language and algorithms, and combine machine learning technology. Code quality, maintainability, and testing are crucial. Only by choosing the right programming language, algorithms and tools according to your needs and writing high-quality code can DeepSeek be successfully implemented.
How to use deepseek to settle accounts
Feb 19, 2025 pm 04:36 PM
Question: Is DeepSeek available for accounting? Answer: No, it is a data mining and analysis tool that can be used to analyze financial data, but it does not have the accounting record and report generation functions of accounting software. Using DeepSeek to analyze financial data requires writing code to process data with knowledge of data structures, algorithms, and DeepSeek APIs to consider potential problems (e.g. programming knowledge, learning curves, data quality)
How to access DeepSeekapi - DeepSeekapi access call tutorial
Mar 12, 2025 pm 12:24 PM
Detailed explanation of DeepSeekAPI access and call: Quick Start Guide This article will guide you in detail how to access and call DeepSeekAPI, helping you easily use powerful AI models. Step 1: Get the API key to access the DeepSeek official website and click on the "Open Platform" in the upper right corner. You will get a certain number of free tokens (used to measure API usage). In the menu on the left, click "APIKeys" and then click "Create APIkey". Name your APIkey (for example, "test") and copy the generated key right away. Be sure to save this key properly, as it will only be displayed once
Major update of Pi Coin: Pi Bank is coming!
Mar 03, 2025 pm 06:18 PM
PiNetwork is about to launch PiBank, a revolutionary mobile banking platform! PiNetwork today released a major update on Elmahrosa (Face) PIMISRBank, referred to as PiBank, which perfectly integrates traditional banking services with PiNetwork cryptocurrency functions to realize the atomic exchange of fiat currencies and cryptocurrencies (supports the swap between fiat currencies such as the US dollar, euro, and Indonesian rupiah with cryptocurrencies such as PiCoin, USDT, and USDC). What is the charm of PiBank? Let's find out! PiBank's main functions: One-stop management of bank accounts and cryptocurrency assets. Support real-time transactions and adopt biospecies
What are the current AI slicing tools?
Nov 29, 2024 am 10:40 AM
Here are some popular AI slicing tools: TensorFlow DataSetPyTorch DataLoaderDaskCuPyscikit-imageOpenCVKeras ImageDataGenerator
