怎么进行JSOUP 爬虫的分析

蜗牛 互联网技术资讯 2021-12-13 33 0

这期内容当中小编将会给大家带来有关怎么进行JSOUP 爬虫的分析,文章内容丰富且以专业的角度为大家分析和叙述,阅读完这篇文章希望大家可以有所收获。

  •  规则编写说明文档

  • 通用选择器(*)是隐含在没有元素选择器提供 (i.e. *.header and .header is equivalent).

    样式 匹配 例子
    * 任何元素 *
    tag 通过Tga标签获取元素 div
    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]

    组合器



    E F an F element descended from an E element div a, .logo h2
    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 h2 ~ p
    E, F, G all matching elements E, F, or G a[href], div, h4

    伪选择器



    :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.

    The above may be combined in any order and with other selectors .light:contains(name):eq(0)

    结构伪选择器




    :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


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