Android中利用jsoup解析html页面

学习jsoup :jsoup学习网站

Android 中使用:

添加依赖

    implementation 'org.jsoup:jsoup:1.10.1'

直接上代码:

package com.loaderman.jsoupdemo;

import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.View;

import org.jsoup.Jsoup;
import org.jsoup.nodes.Document;
import org.jsoup.nodes.Element;
import org.jsoup.select.Elements;

import java.io.IOException;

public class Main2Activity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main2);
        findViewById(R.id.btn).setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                new Thread(new Runnable() {
                    @Override
                    public void run() {
                        try {
                            Document doc = (Document) Jsoup.connect("http://192.168.0.195:8088/news.html").get();//解析html
                            Elements links = doc.select("ul[class=w_newslistpage_list]");//获取li标签且class为w_newslistpage_list的标签
                            for (Element link : links) {
                                Elements li = link.select("li");//查找li标签
                                for (Element element : li) {//遍历
                                    Elements select = element.select("a[title]");//查找a标签且带有title属性的标签
                                    if (select!=null&&select.size()>0){
                                        String linkHref = select.get(0).attr("href");//获取href值
                                        String linkText = select.get(0).text();//获取text
                                        System.out.println("爬虫结果 1 -->  " + linkHref +linkText);
                                    }
                                    Elements select1 = link.select("span[class=date]");//获取span标签且class为date的标签
                                    if (select1!=null&&select1.size()>0){
                                        String date = select1.get(0).text();
                                        System.out.println("爬虫结果 2--> " + date);
                                    }
                                }
                            }
                        } catch (IOException e) {
                            e.printStackTrace();
                        }

                    }
                }).start();
            }
        });
    }
}

小结如下:

解析和遍历一个HTML文档

如何解析一个HTML文档：

String html = "<html><head><title>First parse</title></head>"
  + "<body><p>Parsed HTML into a doc.</p></body></html>";
Document doc = Jsoup.parse(html);

其解析器能够尽最大可能从你提供的HTML文档来创见一个干净的解析结果，无论HTML的格式是否完整。比如它可以处理：

  • 没有关闭的标签 (比如： <p>Lorem <p>Ipsum parses to <p>Lorem</p> <p>Ipsum</p>)
  • 隐式标签 (比如. 它可以自动将 <td>Table data</td>包装成<table><tr><td>?)
  • 创建可靠的文档结构（html标签包含head 和 body，在head只出现恰当的元素）

一个文档的对象模型

  • 文档由多个Elements和TextNodes组成 (
  • 其继承结构如下：Document继承Element继承Node. TextNode继承 Node.
  • 一个Element包含一个子节点集合，并拥有一个父Element。他们还提供了一个唯一的子元素过滤列表。

从一个文件加载一个文档

File input = new File("/tmp/input.html");
Document doc = Jsoup.parse(input, "UTF-8", "http://example.com/");

说明

parse(File in, String charsetName, String baseUri) 这个方法用来加载和解析一个HTML文件。如在加载文件的时候发生错误，将抛出IOException，应作适当处理。

baseUri 参数用于解决文件中URLs是相对路径的问题。如果不需要可以传入一个空的字符串。

另外还有一个方法parse(File in, String charsetName) ，它使用文件的路径做为 baseUri。 这个方法适用于如果被解析文件位于网站的本地文件系统，且相关链接也指向该文件系统。

使用选择器语法来查找元素

File input = new File("/tmp/input.html");
Document doc = Jsoup.parse(input, "UTF-8", "http://example.com/");

Elements links = doc.select("a[href]"); //带有href属性的a元素
Elements pngs = doc.select("img[src$=.png]");
  //扩展名为.png的图片

Element masthead = doc.select("div.masthead").first();
  //class等于masthead的div标签

Elements resultLinks = doc.select("h3.r > a"); //在h3元素之后的a元素

说明

jsoup elements对象支持类似于CSS (或jquery)的选择器语法，来实现非常强大和灵活的查找功能。.

这个select 方法在Document, Element,或Elements对象中都可以使用。且是上下文相关的，因此可实现指定元素的过滤，或者链式选择访问。

Select方法将返回一个Elements集合，并提供一组方法来抽取和处理结果。

Selector选择器概述

  • tagname: 通过标签查找元素，比如：a
  • ns|tag: 通过标签在命名空间查找元素，比如：可以用 fb|name 语法来查找 <fb:name> 元素
  • #id: 通过ID查找元素，比如：#logo
  • .class: 通过class名称查找元素，比如：.masthead
  • [attribute]: 利用属性查找元素，比如：[href]
  • [^attr]: 利用属性名前缀来查找元素，比如：可以用[^data-] 来查找带有HTML5 Dataset属性的元素
  • [attr=value]: 利用属性值来查找元素，比如：[width=500]
  • [attr^=value], [attr$=value], [attr*=value]: 利用匹配属性值开头、结尾或包含属性值来查找元素，比如：[href*=/path/]
  • [attr~=regex]: 利用属性值匹配正则表达式来查找元素，比如： img[src~=(?i)\.(png|jpe?g)]
  • *: 这个符号将匹配所有元素

Selector选择器组合使用

  • el#id: 元素+ID，比如： div#logo
  • el.class: 元素+class，比如： div.masthead
  • el[attr]: 元素+class，比如： a[href]
  • 任意组合，比如：a[href].highlight
  • ancestor child: 查找某个元素下子元素，比如：可以用.body p 查找在"body"元素下的所有 p元素
  • parent > child: 查找某个父元素下的直接子元素，比如：可以用div.content > p 查找 p 元素，也可以用body > * 查找body标签下所有直接子元素
  • siblingA + siblingB: 查找在A元素之前第一个同级元素B，比如：div.head + div
  • siblingA ~ siblingX: 查找A元素之前的同级X元素，比如：h1 ~ p
  • el, el, el:多个选择器组合，查找匹配任一选择器的唯一元素，例如：div.masthead, div.logo

伪选择器selectors

  • :lt(n): 查找哪些元素的同级索引值（它的位置在DOM树中是相对于它的父节点）小于n，比如：td:lt(3) 表示小于三列的元素
  • :gt(n):查找哪些元素的同级索引值大于n，比如： div p:gt(2)表示哪些div中有包含2个以上的p元素
  • :eq(n): 查找哪些元素的同级索引值与n相等，比如：form input:eq(1)表示包含一个input标签的Form元素
  • :has(seletor): 查找匹配选择器包含元素的元素，比如：div:has(p)表示哪些div包含了p元素
  • :not(selector): 查找与选择器不匹配的元素，比如： div:not(.logo) 表示不包含 class="logo" 元素的所有 div 列表
  • :contains(text): 查找包含给定文本的元素，搜索不区分大不写，比如： p:contains(jsoup)
  • :containsOwn(text): 查找直接包含给定文本的元素
  • :matches(regex): 查找哪些元素的文本匹配指定的正则表达式，比如：div:matches((?i)login)
  • :matchesOwn(regex): 查找自身包含文本匹配指定正则表达式的元素
  • 注意：上述伪选择器索引是从0开始的，也就是说第一个元素索引值为0，第二个元素index为1等

具体api如下:

CSS-like element selector, that finds elements matching a query.

Selector syntax

A selector is a chain of simple selectors, separated by combinators. Selectors are case insensitive (including against elements, attributes, and attribute values).

The universal selector (*) is implicit when no element selector is supplied (i.e. *.header and .header is equivalent).

PatternMatchesExample
* any element *
tag elements with the given tag name div
*|E elements of type E in any namespace ns *|name finds <fb:name> elements
ns|E elements of type E in the namespace ns fb|name finds <fb:name> elements
#id elements with attribute ID of "id" div#wrap, #logo
.class elements with a class name of "class" div.left, .result
[attr] elements with an attribute named "attr" (with any value) a[href], [title]
[^attrPrefix] elements with an attribute name starting with "attrPrefix". Use to find elements with HTML5 datasets [^data-], div[^data-]
[attr=val] elements with an attribute named "attr", and value equal to "val" img[width=500], a[rel=nofollow]
[attr="val"] elements with an attribute named "attr", and value equal to "val" span[hello="Cleveland"][goodbye="Columbus"], a[rel="nofollow"]
[attr^=valPrefix] elements with an attribute named "attr", and value starting with "valPrefix" a[href^=http:]
[attr$=valSuffix] elements with an attribute named "attr", and value ending with "valSuffix" img[src$=.png]
[attr*=valContaining] elements with an attribute named "attr", and value containing "valContaining" a[href*=/search/]
[attr~=regex] elements with an attribute named "attr", and value matching the regular expression img[src~=(?i)\\.(png|jpe?g)]
  The above may be combined in any order div.header[title]
 

Combinators
E F an F element descended from an E element div a, .logo h1
E > F an F direct child of E ol > li
E + F an F element immediately preceded by sibling E li + li, div.head + div
E ~ F an F element preceded by sibling E h1 ~ p
E, F, G all matching elements E, F, or G a[href], div, h3
 

Pseudo selectors
:lt(n) elements whose sibling index is less than n td:lt(3) finds the first 3 cells of each row
:gt(n) elements whose sibling index is greater than n td:gt(1) finds cells after skipping the first two
:eq(n) elements whose sibling index is equal to n td:eq(0) finds the first cell of each row
:has(selector) elements that contains at least one element matching the selector div:has(p) finds divs that contain p elements
:not(selector) elements that do not match the selector. See also Elements.not(String) div:not(.logo) finds all divs that do not have the "logo" class.

div:not(:has(div)) finds divs that do not contain divs.
:contains(text) elements that contains the specified text. The search is case insensitive. The text may appear in the found element, or any of its descendants. p:contains(jsoup) finds p elements containing the text "jsoup".
:matches(regex) elements whose text matches the specified regular expression. The text may appear in the found element, or any of its descendants. td:matches(\\d+) finds table cells containing digits. div:matches((?i)login) finds divs containing the text, case insensitively.
:containsOwn(text) elements that directly contain the specified text. The search is case insensitive. The text must appear in the found element, not any of its descendants. p:containsOwn(jsoup) finds p elements with own text "jsoup".
:matchesOwn(regex) elements whose own text matches the specified regular expression. The text must appear in the found element, not any of its descendants. td:matchesOwn(\\d+) finds table cells directly containing digits. div:matchesOwn((?i)login) finds divs containing the text, case insensitively.
:containsData(data) elements that contains the specified data. The contents of script and style elements, and comment nodes (etc) are considered data nodes, not text nodes. The search is case insensitive. The data may appear in the found element, or any of its descendants. script:contains(jsoup) finds script elements containing the data "jsoup".
  The above may be combined in any order and with other selectors .light:contains(name):eq(0)
:matchText treats text nodes as elements, and so allows you to match against and select text nodes.

Note that using this selector will modify the DOM, so you may want to clone your document before using.

 p:matchText:firstChild with input <p>One<br />Two</p> will return one PseudoTextElement with text "One".

Structural pseudo selectors
:root The element that is the root of the document. In HTML, this is the html element :root
:nth-child(an+b)

elements that have an+b-1 siblings before it in the document tree, for any positive integer or zero value of n, and has a parent element. For values of a and b greater than zero, this effectively divides the element's children into groups of a elements (the last group taking the remainder), and selecting the bth element of each group. For example, this allows the selectors to address every other row in a table, and could be used to alternate the color of paragraph text in a cycle of four. The a and b values must be integers (positive, negative, or zero). The index of the first child of an element is 1.

In addition to this, :nth-child() can take odd and even as arguments instead. odd has the same signification as 2n+1, and even has the same signification as 2n.		 tr:nth-child(2n+1) finds every odd row of a table. :nth-child(10n-1) the 9th, 19th, 29th, etc, element. li:nth-child(5) the 5h li
:nth-last-child(an+b) elements that have an+b-1 siblings after it in the document tree. Otherwise like :nth-child() tr:nth-last-child(-n+2) the last two rows of a table
:nth-of-type(an+b) pseudo-class notation represents an element that has an+b-1 siblings with the same expanded element name before it in the document tree, for any zero or positive integer value of n, and has a parent element img:nth-of-type(2n+1)
:nth-last-of-type(an+b) pseudo-class notation represents an element that has an+b-1 siblings with the same expanded element name after it in the document tree, for any zero or positive integer value of n, and has a parent element img:nth-last-of-type(2n+1)
:first-child elements that are the first child of some other element. div > p:first-child
:last-child elements that are the last child of some other element. ol > li:last-child
:first-of-type elements that are the first sibling of its type in the list of children of its parent element dl dt:first-of-type
:last-of-type elements that are the last sibling of its type in the list of children of its parent element tr > td:last-of-type
:only-child elements that have a parent element and whose parent element hasve no other element children  
:only-of-type an element that has a parent element and whose parent element has no other element children with the same expanded element name  
:empty elements that have no children at all

posted on 2018-12-27 15:19  LoaderMan  阅读(1748)  评论(0)  编辑  收藏  举报

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