HTML页面解析组件-Jsoup使用

原文地址: http://blog.sina.com.cn/s/blog_7227719a0100lpix.html

java端解析HTML页面内容

Jsoup把HTML的解析变为DOM的方式，类似于在HTML页面中直接用JS操作。

使用方法：

Document doc = Jsoup.parse(new URL(“http://www.baidu.com”),5000);

这是从一个URL地址获取HTML页面内容，然后直接处理成一个DOM的对象。当然，也可以传入已有的HTML页面String，

甚至于File对象，输入流对象。

元素用Element对象封装

元素集合用Elements对象封装（LinkedHashSet）

Elements elems = doc.getElementsByTagName_r("A");

或

Elemens elems = doc.getElemensByName("name”);

。。。

最方便的莫过于类似于XPATH的select方法

Elements elems  = doc.select(“A[href^=http]”); //href 以http开头

更多规则：

Selector overview

tagname

: find elements by tag, e.g. 

a

ns|tag

: find elements by tag in a namespace, e.g. 

fb|name

 finds 

<fb:name>

 elements

#id

: find elements by ID, e.g. 

#logo

.class

: find elements by class name, e.g. 

.masthead

[attribute]

: elements with attribute, e.g. 

[href]

[^attr]

: elements with an attribute name prefix, e.g. 

[^data-]

 finds elements with HTML5 dataset attributes

[attr=value]

: elements with attribute value, e.g. 

[width=500]

[attr^=value]

, 

[attr$=value]

, 

[attr*=value]

: elements with attributes that start with, end with, or contain the value, e.g. 

[href*=/path/]

[attr~=regex]

: elements with attribute values that match the regular expression;e.g.

img[src~=(?i)\.(png|jpe?g)]

*

: all elements, e.g. 

*

Selector combinations

el#id

: elements with ID, e.g. 

div#logo

el.class

: elements with class, e.g. 

div.masthead

el[attr]

: elements with attribute, e.g. 

a[href]

Any combination, e.g. 

a[href].highlight

ancestor child

: child elements that descend from ancestor, e.g. 

.body p

 finds 

p

 elements anywhere under a block with class "body"

parent > child

: child elements that descend directly from parent, e.g. 

div.content > p

finds 

p

 elements; and 

body > *

 finds
the direct children of the body tag

siblingA + siblingB

: finds sibling B element immediately preceded by sibling A, e.g.

div.head + div

siblingA ~ siblingX

: finds sibling X element preceded by sibling A, e.g. 

h1 ~ p

el, el, el

: group multiple selectors, find unique elements that match any of the selectors; e.g. 

div.masthead, div.logo

Pseudo selectors

:lt(n)

: find elements whose sibling index (i.e. its position in the DOM tree relative to its parent) is less than 

n

; e.g. 

td:lt(3)

:gt(n)

: find elements whose sibling index is greater than 

n

; e.g. 

div p:gt(2)

:eq(n)

: find elements whose sibling index is equal to 

n

; e.g. 

form input:eq(1)

:has(seletor)

: find elements that contain elements matching the selector; e.g. 

div:has(p)

:not(selector)

: find elements that do not match the selector; e.g. 

div:not(.logo)

:contains(text)

: find elements that contain the given text. The search is case-insensitive; e.g. 

p:contains(jsoup)

:containsOwn(text)

: find elements that directly contain the given text

:matches(regex)

: find elements whose text matches the specified regular expression; e.g.

div:matches((?i)login)

:matchesOwn(regex)

: find elements whose own text matches the specified regular expression
Note that the above indexed pseudo-selectors are 0-based, that is, the first element is at index 0, the second at 1, etc

See the 

Selector

 API reference for the full supported list and details.

优点：

1、使用非常简单，类似于JS操作DOM，很直观，熟悉

2、选择器很强大，可以很方便的查找元素