python xpath 解析网页应用实例

Myth丶恋晨 2022-05-20 02:48 172阅读 0赞

首先请阅读文档 http://www.runoob.com/xpath/xpath-tutorial.html ，这里有背景和概念的介绍。

下面展示一些实际中的应用。

一、准备：

from lxml import etree # 加载模块

html='''
    <html>
        <head>
            <title>哈哈测试一下</title>
            <link type="text/css" rel="stylesheet" href="haha.css" />
            <link type="text/css" rel="stylesheet" href="haha1.css" />
            <link type="text/css" rel="stylesheet" href="haha2.css" />
            <script type="text/javascript" src="haha.js"></script>
            <script type="text/javascript" src="haha1.js"></script>
            <script type="text/javascript" src="haha2.js"></script>
        </head>
        <body>
            <div id="id1" class="class1">
                <div id="id2" class="class2">
                    <ul class="cls_ul1">
                        <li class="cls_li1">
                            <div class="cls_3">
                                <span>span_text1</span>
                                <span>span_text2</span>
                                <i>text_1</i>
                            </div>
                            <div>
                                <a href="a_1.html">a_1</a>
                                <a href="a_2.html">a_2</a>
                                <a href="a_3.html">a_3</a>
                            </div>
                            <div class="cls_4">
                                <a href="a_4.html">
                                    <img href="a_img1.jpg" />
                                </a>
                            </div>
                        </li>
                        <li class="cls_li1">
                            <div class="cls_3">
                                <span>span_text3</span>
                                <span>span_text4</span>
                                <i>text_2</i>
                                <i>text_22</i>
                            </div>
                            <div>
                                <a href="a_4.html">a_4</a>
                                <a href="a_5.html">a_5</a>
                                <a href="a_6.html">a_6</a>
                            </div>
                            <div class="cls_4">
                                <a href="a_5.html">
                                    <img href="a_img2.jpg" />
                                </a>
                            </div>
                        </li>
                    </ul>
                </div>
                <div id="id3" class="class3">
                    <ul class="cls_ul2">
                        <li class="cls_li2">
                            <div class="cls_5">
                                <span>span_text5</span>
                                <span>span_text6</span>
                                <i>text_3</i>
                            </div>
                            <div>
                                <a href="a_1.html">a_1</a>
                                <a href="a_2.html">a_2</a>
                                <a href="a_3.html">a_3</a>
                            </div>
                            <div class="cls_6">
                                <a href="a_4.html">
                                    <img href="a_img3.jpg" />
                                </a>
                            </div>
                        </li>
                        <li class="cls_li2">
                            <div class="cls_5">
                                <span>span_text7</span>
                                <span>span_text8</span>
                                <i>text_4</i>
                            </div>
                            <div>
                                <a href="a_4.html">a_4</a>
                                <a href="a_5.html">a_5</a>
                                <a href="a_6.html">a_6</a>
                            </div>
                            <div class="cls_6">
                                <a href="a_5.html">
                                    <img href="a_img4.jpg" />
                                </a>
                            </div>
                        </li>
                    </ul>
                </div>
            </div>
        </body>
    </html>
    '''

html_data = etree.HTML(html) #

二、应用：

# 从根节点开始，沿着XML路径一步一步选择节点，text()表示节点内容
    content = html_data.xpath("/html/head/title/text()")
    for con in content:
        print(con)
    >>>哈哈测试一下

# 从根节点开始，沿着XML路径一步一步选择节点，text表示节点内容
    node = html_data.xpath("/html/head/title") 
    for n in node:
        print(n.text)
    >>>哈哈测试一下

# 从文档中某个节点开始，不考虑此节点位置，text()表示节点内容
    content = html_data.xpath("//title/text()") 
    for con in content:
        print(con)
    >>>哈哈测试一下

# 获取所有div(html/body/div/div)的id属性值
    nodes = html_data.xpath("/html/body/div/div") 
    for i in range(len(nodes)): # 循环节点
        content = nodes[i].xpath("@id")
        for con in content:
            print(con)
    >>>id2
       id3

# body节点下某节点的属性值
    content = html_data.xpath("body/div/div[@id='id2']/ul/li[1]/div[2]/a/@href") 
    for con in content:
        print(con)
    >>>a_1.html
       a_2.html
       a_3.html

# div[@id='id2']节点下某节点的属性值
    content = html_data.xpath("//div[@id='id2']/ul/li[1]/div[2]/a/@href") 
    for con in content:
        print(con)
    >>>a_1.html
       a_2.html
       a_3.html

# div[@id='id2']节点下某节点的内容
    content = html_data.xpath("//div[@id='id2']/ul/li[1]/div[2]/a/text()") 
    for con in content:
        print(con)
    >>>a_1
       a_2
       a_3

# 用'*'来匹配任何元素
    content = html_data.xpath("*//div[@id='id2']/ul/li[1]/div[2]/a/text()") 
    for con in content:
        print(con)
    >>>a_1
       a_2
       a_3

# 选取多个节点
    nodes = html_data.xpath("//i|//span") 
    for i in range(len(nodes)):
        print(nodes[i].text)
    >>>span_text1
       span_text2
       text_1
       span_text3
       span_text4
       text_2
       text_22
       span_text5
       span_text6
       text_3
       span_text7
       span_text8
       text_4

# 选取所有li节点
    nodes = html_data.xpath("//li") 
    for i in range(len(nodes)):
        content = nodes[i].xpath("div/@class") # li节点下所有div节点的class属性值
        print(i,'='*5)
        for con in content:
            print(con)
    >>>0 =====
       cls_3
       cls_4
       1 =====
       cls_3
       cls_4
       2 =====
       cls_5
       cls_6
       3 =====
       cls_5
       cls_6

# 选取所有li节点
    nodes = html_data.xpath("//li") 
    for i in range(len(nodes)):
        content = nodes[i].xpath("div[last()]/@class") # li节点下最后一个div节点的class属性值
        print(i,'='*5)
        for con in content:
            print(con)
    >>>0 =====
       cls_4
       1 =====
       cls_4
       2 =====
       cls_6
       3 =====
       cls_6

# 这里应用了'..'和'@'，其中'..'表示父节点，具体就是上一步(title)的父节点head；'@'表示属性，就是它后面接是属性名，在这里的意思就是属性href的内容
    content = html_data.xpath("/html/head/title/../link/@href") 
    for con in content:
        print(con)
    >>>haha.css
       haha1.css
       haha2.css

# div[@class='cls_3']的子节点span的兄弟节点i
    nodes = html_data.xpath("//div[@class='cls_3']/span/following-sibling::i") 
    for i in range(len(nodes)):
        content = nodes[i].xpath("./text()") # 当前节点的内容
        for con in content:
            print(con)
    >>>text_1
       text_2
       text_22

# li[@class='cls_li1']后代节点里第一个div的class属性值
    content = html_data.xpath("//li[@class='cls_li1']/descendant::div[1]/@class") 
    for con in content:
        print(con)
    >>>cls_3
       cls_3

# li[@class='cls_li1']后代节点里span的内容
    content = html_data.xpath("//li[@class='cls_li1']/descendant::span/text()") 
    for con in content:
        print(con)
    >>>span_text1
       span_text2
       span_text3
       span_text4

# 用'*'来匹配任何元素，且不包含class属性的div节点
    content = html_data.xpath("*//div[@id='id2']/ul/li[1]/div[not(@class)]/a/text()")
    for con in content:
        print(con)
    >>>a_1
    >>>a_2
    >>>a_3

==================================

# 多个条件的情况
    xpath("//div[@class='cls_1' and @id='id_1']")
    # contains 包含的情况
    xpath("//div[contains(@class,'cls_1')]") # <div class='cls_1 cls_2'></div>