爬虫 - xpath 匹配

例题


import lxml.html

test_data = """
        <div>
            <ul>
                 <li class="item-0"><a href="link1.html" id="places_neighbours__row">9,596,960first item</a></li>
                 <li class="item-1"><a href="link2.html">second item</a></li>
                 <li class="item-inactive"><a href="link3.html">third item</a></li>
                 <li class="item-1"><a href="link4.html" id="places_neighbours__row">fourth item</a></li>
                 <li class="item-0"><a href="link5.html">fifth item</a></li>
                 <li class="good-0"><a href="link5.html">fifth item</a></li>
             </ul>
             <book>
                    <title lang="aaengbb">111111</title>
                    <price id="places_neighbours__row">29.99</price>
            </book>
            <book>
                <title lang="zh">222222</title>
                <price>39.95</price>
            </book>
            <book>
                <title>33333</title>
                <price>40</price>
            </book>
         </div>
        <a>
            <book>
                <title>123</title>
            </book>

        </a>

        """

"""
/ 从根标签开始 必须具有严格的父子关系
// 从当前标签  后续节点含有即可选出
* 通配符，选择所有
//div/book[1]/title 选择div下第一个book标签的title元素
//div/book/title[@lang="zh"]选择title属性含有lang且内容是zh的title元素
//div/book/title //book/title //title //div//title 具有相同的结果，因为使用相对路径最终都指向title
//book/title/@* 将title所有的属性值选择出来
//book/title/text() 将title的内容选择出来，使用内置text()函数
//a[@href="link1.html" and @id="places_neighbours__row"]
//a[@href="link1.html" or @id="places_neighbours__row"]
//div/book[last()]/title/text() 将最后一个book元素选出
//div/book[price > 39]/title 将book子标签price数值大于39的选择出来
//li[starts-with(@class,'item')] 将class属性前缀是item的li标签选出
//title[contains(@lang,'eng')] 将title属性lang含有eng关键字的标签选出
"""

html = lxml.html.fromstring(test_data)

#html_data = html.xpath('//div/book/title/text()')
#html_data = html.xpath('//div/book[1]/title/text()')
#html_data = html.xpath('//div/book/title[@lang="zh"]/text()')
#html_data = html.xpath('//div/book/title/text()')
# html_data = html.xpath('//book/title/text()')
# html_data = html.xpath('//title/text()')
# html_data = html.xpath('//div//title/text()')
# html_data = html.xpath('//book/title/@*')

# html_data = html.xpath('//a[@href="link1.html" and @id="places_neighbours__row"]/text()')
#html_data = html.xpath('//a[@href="link2.html"]/text()')
# html_data = html.xpath('//div/ul/li/a[@id]/text()')
# html_data = html.xpath('//a[@href="link1.html" and @id="places_neighbours__row"]/@*')
# html_data = html.xpath('//a[@href="link1.html" and @id="places_neighbours__row"]/@href')
# html_data = html.xpath('//a[@href="link1.html" or @id="places_neighbours__row"]/text()')
# html_data = html.xpath('//div/book[last()]/title/text()')
#html_data = html.xpath('//div/book[price > 39]/title/text()')
# html_data = html.xpath('//li[starts-with(@class,"item")]/a/text()')
html_data = html.xpath('//title[contains(@lang,"eng")]/text()')

for i in html_data:
    print(i)