使用xpath解析一个简单的html文件，想获取href属性的值：

html = etree.parse('test.html',etree.HTMLParser())

print(html.xpath('//li/a@href'))

运行后报错：lxml.etree.XPathEvalError: Invalid expression

Traceback (most recent call last):

File "D:/PythonWorkstation/python3_spider/chap04_解析库/test_xpath.py", line 35, in

print(html.xpath('//li/a@href'))

File "src\lxml\lxml.etree.pyx", line 2272, in lxml.etree._ElementTree.xpath (src\lxml\lxml.etree.c:67766)

File "src\lxml\xpath.pxi", line 359, in lxml.etree.XPathDocumentEvaluator.__call__ (src\lxml\lxml.etree.c:171818)

File "src\lxml\xpath.pxi", line 227, in lxml.etree._XPathEvaluatorBase._handle_result (src\lxml\lxml.etree.c:170189)

lxml.etree.XPathEvalError: Invalid expression

原因分析：

获取属性的值的时候，需要给属性加上中括号。

修改后的代码：

html = etree.parse('test.html',etree.HTMLParser())

print(html.xpath('//li/a/@href'))

再次运行：

D:\python3\Anaconda3\python.exe D:/PythonWorkstation/test_xpath.py

['linkl.html', 'link2.html', 'link3.html', 'link4.html']

Process finished with exit code 0