正则表达式常用语法速查+一个简单使用案例
文章目录
-
- 一、常用元字符（注意区分大小写，大写是相反的意思）
- 二、重复量词与贪婪非贪婪模式
- 三、自定义字符集合与字符边界问题
-
- 自定义字符集合
- 字符边界问题（匹配的不是字符而是位置，符合某种条件的位置）
- 四、选择符和分组以及反向引用
-
- 选择符和分组
- 反向引用
- 五、零宽断言
- 六、小案例练习
-
- 获取网页中所有超链接
-
- - 示例网页源码：
- - 正则表达式
- -加一个零宽断言
- 附：常用字符
一、常用元字符（注意区分大小写，大写是相反的意思）
\d 任意一个数字 0-9的任意一个
\w 任意一个字母或数字或下划线，也就是a-z A-Z 0-9 _任意一个
\s 包括空格 制表符 换行符等空白字符的其中任意一个
. 小数点可以匹配任意一个字符（除了换行符）。如果要匹配包括\n在内的所有字符，一般用[\s\S]
二、重复量词与贪婪非贪婪模式
{n} 表达式重复n次
{m,n}表达式至少重复m次，最多重复n次
{m,}表达式至少重复m次
? 匹配表达式0次或者1次数，相当于{0,1}
+ 表达式至少出现1次 相当于{1,}
* 表达式不出现或出现人一次，相当于{0,}
贪婪模式：匹配字符越多越好，是默认的
非贪婪模式：匹配字符越少越好，修饰匹配次数的特殊符号后再加上一个?号
三、自定义字符集合与字符边界问题
自定义字符集合
[ab5@] 匹配a或b或5或@
[^abc] 匹配abc之外的任意一个字符
[f-k] 匹配f~k之间的任意一个字符
[^A-F0-3] 匹配A~F 0~3之外的任意一个字符
字符边界问题（匹配的不是字符而是位置，符合某种条件的位置）
^ 与字符串开始的地方匹配
$ 与字符串结束的地方匹配
\b 匹配一个单词边界
-\b匹配这样一个位置：前面的字符和后面的字符不全是\w
四、选择符和分组以及反向引用
选择符和分组
|【分支结构】 左右两边表达式之间或关系，匹配左边或右边
() 【捕获组】 在被修饰匹配次数的时候，括号中的表达式可以作为整体被修饰
取匹配结果的时候，括号中的表达式匹配到的内容可以被单独得到
每一对括号会分配一个编号，使用()的捕获根据左括号的顺序从1开始自动编号，捕获元素编号为0的第一个捕获是由整个正则表达式模式匹配的文本
(?:Expression) 一些表达式中，不得不使用() 但又不需要保存()中子表达式匹配的内容，这时可以用非捕获组来抵消使用()带来的副作用
反向引用
每一对()会分配一个编号，使用()的捕获根据左括号的顺序从1开始自动编号
通过反向引用，可以对分组已捕获的字符串进行引用
五、零宽断言
(?=exp) 断言自身出现的位置的后面能匹配表达式exp
(?<=exp) 断言自身出现的位置的前面能匹配表达式exp
(?!exp) 断言此位置的后面不能匹配表达式exp
(?六、小案例练习
获取网页中所有超链接
- 示例网页源码：
<html>
<head>
<meta name="viewport" content="width=device-width,user-scalable=0,initial-scale=1.0, minimum-scale=1.0, maximum-scale=1.0"/>
<meta charset="utf-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge,chrome=1">
<title>重庆城市管理职业学院title>
<link type="text/css" href="/_css/_system/system.css" rel="stylesheet"/>
<link type="text/css" href="/_upload/site/1/style/1/1.css" rel="stylesheet"/>
<link type="text/css" href="/_upload/site/00/03/3/style/4/4.css" rel="stylesheet"/>
<LINK href="/_css/tpl2/system.css" type="text/css" rel="stylesheet">
<LINK href="/_css/tpl2/default/default.css" type="text/css" rel="stylesheet">
<link type="text/css" href="/_js/_portletPlugs/simpleNews/css/simplenews.css" rel="stylesheet" />
<link type="text/css" href="/_js/_portletPlugs/datepicker/css/datepicker.css" rel="stylesheet" />
<link type="text/css" href="/_js/_portletPlugs/sudyNavi/css/sudyNav.css" rel="stylesheet" />
<script language="javascript" src="/_js/jquery.min.js" sudy-wp-context="" sudy-wp-siteId="3">script>
<script language="javascript" src="/_js/jquery.sudy.wp.visitcount.js">script>
<script type="text/javascript" src="/_js/_portletPlugs/datepicker/js/jquery.datepicker.js">script>
<script type="text/javascript" src="/_js/_portletPlugs/datepicker/js/datepicker_lang_HK.js">script>
<script type="text/javascript" src="/_js/_portletPlugs/sudyNavi/jquery.sudyNav.js">script>
<link rel="stylesheet" href="/_upload/tpl/00/03/3/template3/style.css" type="text/css" media="all" />
<link rel="stylesheet" href="/_upload/tpl/00/03/3/template3/extends/extends.css" type="text/css" media="all" />
<link href="/_upload/tpl/00/03/3/template3/css/media.css" rel="stylesheet">
<script type="text/javascript" src="/_upload/tpl/00/03/3/template3/js/sudy.js">
script>
<script type="text/javascript" src="/_upload/tpl/00/03/3/template3/extends/extends.js">
script>
<script type="text/javascript">
$(function(){
var test = window.location.host;
if (test == "www.cswu.cn"){
$(".foot-r").addClass("foot-bq")
}else{
$(".foot-r").removeClass("foot-bq")
}
})
script>
<script type="text/javascript">
$(function(){
$(".scroll").sudyScroll({
width: 350, // 单元格宽度
height: 85, // 单元格高度
display: 3, // 显示几个单元
step: 3, // 每次交替增加几个单元，值不能大于display
dir:"y", // 交替方向，纵向为"y"，水平为"x"，默认为"y"纵向交替
auto:true, // 是否自动交替,默认为自动
speed:500, // 交替速度
hoverPause:5000, // 交替暂留时间
navigation:false, // 是否显示导航按钮
navTrigger:"click", // 导航按钮事件
pagination:true, // 是否显示索引按钮
pagTrigger:"mouseenter" //索引按钮事件
});
});
script>
head>
<body>
<link custom="self" href="/_upload/tpl/00/03/3/template3/css/media.css" rel="stylesheet">
<div class="wrapper main_head" id="header">
<div class="top">
<div class="inner clearfix">
<div class="top_l" frag="面板20">
<div frag="窗口20">
<div id="wp_nav_w20">
<ul class="wp_nav" data-nav-config="{drop_v: 'down', drop_w: 'right', dir: 'y', opacity_main: '-1', opacity_sub: '-1', dWidth: '0'}">
<li class="nav-item i1 ">
<a href="/57/list.htm" title="学生" target="_self"><span class="item-name">学生span>a><i class="mark">i>
li>
<li class="nav-item i2 ">
<a href="/58/list.htm" title="教工" target="_self"><span class="item-name">教工span>a><i class="mark">i>
li>
<li class="nav-item i3 ">
<a href="/60/list.htm" title="考生" target="_self"><span class="item-name">考生span>a><i class="mark">i>
li>
<li class="nav-item i4 ">
<a href="/59/list.htm" title="校友" target="_self"><span class="item-name">校友span>a><i class="mark">i>
li>
<li class="nav-item i5 ">
<a href="/61/list.htm" title="访客" target="_self"><span class="item-name">访客span>a><i class="mark">i>
li>
ul>
div>
div>
div>
<div class="top_r" frag="面板24">
<div frag="窗口24">
<div id="wp_nav_w24">
<ul class="wp_nav" data-nav-config="{drop_v: 'down', drop_w: 'right', dir: 'y', opacity_main: '-1', opacity_sub: '-1', dWidth: '0'}">
<li class="nav-item i1 ">
<a href="http://www.cswu.cn/english/main.htm" title="English" target="_blank"><span class="item-name">Englishspan>a><i class="mark">i>
li>
<li class="nav-item i2 ">
<a href="http://eip.cswu.cn/EIP/nonlogin/user/index.htm" title="一站式服务大厅" target="_blank"><span class="item-name">一站式服务大厅span>a><i class="mark">i>
li>
<li class="nav-item i3 ">
<a href="http://ky.cswu.cn:8083" title="校园VR导视" target="_blank"><span class="item-name">校园VR导视span>a><i class="mark">i>
li>
ul>
div>
div>
div>
div>
div>
<div class="inner">
<div class="head clearfix" frag="面板1">
<div class="logo" frag="窗口1" portletmode="simpleSiteAttri">
<a class="site-url" href="/main.htm"><img src="/_upload/tpl/00/03/3/template3/images/logo.png" width="329" height="65"/>a>
div>
<div class="search_box" frag="窗口29">
<form method="POST" action="/_web/search/doSearch.do?locale=zh_CN&request_locale=zh_CN&_p=YXM9MyZ0PTMmZD03JnA9MSZtPVNTJmM9dzI5JnY9QyY_" target="_blank" onsubmit="if ($('#keyword').val() === '请输入关键字') { $('#keyword').val(''); }">
<div class="wp_search">
<table>
<tr>
<td height="25px">
<input id="keyword" name="keyword" style="width: 150px" class="keyword" type="text" value="请输入关键字" onfocus="if (this.value === '请输入关键字') { this.value = ''; }"
onblur="if (this.value === '') { this.value = '请输入关键字'; }" />
td>
<td>
<input name="btnsearch" class="search" type="submit" value=""/>
td>
tr>
table>
div>
form>
div>
div>
<div class="navbar" frag="面板2">
<div class="navbox" frag="窗口2">
<div id="wp_nav_w2">
<ul class="wp_nav" data-nav-config="{drop_v: 'down', drop_w: 'right', dir: 'y', opacity_main: '1', opacity_sub: '0.8', dWidth: '0'}">
<li class="nav-item i1 ">
<a href="/main.htm" title="学校首页" target="_self"><span class="item-name">学校首页span>a><i class="mark">i>
li>
<li class="nav-item i2 ">
<a href="/25/list.htm" title="学校概况" target="_self"><span class="item-name">学校概况span>a><i class="mark">i>
<ul class="sub-nav">
<li class="nav-item i2-1 ">
<a href="/66/list.htm" title="学校简介" target="_self"><span class="item-name">学校简介span>a><i class="mark">i>
li>
<li class="nav-item i2-2 ">
<a href="/67/list.htm" title="现任领导" target="_self"><span class="item-name">现任领导span>a><i class="mark">i>
li>
<li class="nav-item i2-3 ">
<a href="http://www.cswu.cn/2016/0517/c68a5998/page.htm" title="学校标志" target="_self"><span class="item-name">学校标志span>a><i class="mark">i>
li>
<li class="nav-item i2-4 ">
<a href="/69/list.htm" title="办学成果" target="_self"><span class="item-name">办学成果span>a><i class="mark">i>
li>
<li class="nav-item i2-5 ">
<a href="http://ky.cswu.cn:8083" title="校园导视" target="_blank"><span class="item-name">校园导视span>a><i class="mark">i>
li>
ul>
li>
<li class="nav-item i3 ">
<a href="/26/list.htm" title="机构设置" target="_self"><span class="item-name">机构设置span>a><i class="mark">i>
li>
<li class="nav-item i4 ">
<a href="/44/list.htm" title="人才培养" target="_self"><span class="item-name">人才培养span>a><i class="mark">i>
<ul class="sub-nav">
<li class="nav-item i4-1 ">
<a href="http://www.cswu.cn/jwc/" title="高职教育" target="_blank"><span class="item-name">高职教育span>a><i class="mark">i>
li>
<li class="nav-item i4-2 ">
<a href="http://www.cswu.cn/jxjyxy" title="继续教育" target="_blank"><span class="item-name">继续教育span>a><i class="mark">i>
li>
ul>
li>
<li class="nav-item i5 ">
<a href="http://www.cswu.cn/kjc/" title="科学研究" target="_blank"><span class="item-name">科学研究span>a><i class="mark">i>
li>
<li class="nav-item i6 ">
<a href="/28/list.htm" title="招生就业" target="_self"><span class="item-name">招生就业span>a><i class="mark">i>
<ul class="sub-nav">
<li class="nav-item i6-1 ">
<a href="http://zs.cswu.cn/" title="招生工作" target="_blank"><span class="item-name">招生工作span>a><i class="mark">i>
li>
<li class="nav-item i6-2 ">
<a href="http://www.cswu.cn/jyzdzx/" title="就业工作" target="_blank"><span class="item-name">就业工作span>a><i class="mark">i>
li>
ul>
li>
<li class="nav-item i7 ">
<a href="/32/list.htm" title="合作交流" target="_blank"><span class="item-name">合作交流span>a><i class="mark">i>
<ul class="sub-nav">
<li class="nav-item i7-1 ">
<a href="http://www.cswu.cn/cjrhzx/" title="产教融合中心" target="_blank"><span class="item-name">产教融合中心span>a><i class="mark">i>
li>
ul>
li>
<li class="nav-item i8 ">
<a href="/45/list.htm" title="文化生活" target="_self"><span class="item-name">文化生活span>a><i class="mark">i>
<ul class="sub-nav">
<li class="nav-item i8-1 ">
<a href="http://www.cswu.cn/xsc/" title="青春学工" target="_blank"><span class="item-name">青春学工span>a><i class="mark">i>
li>
<li class="nav-item i8-2 ">
<a href="/38/list.htm" title="讲座信息" target="_self"><span class="item-name">讲座信息span>a><i class="mark">i>
li>
<li class="nav-item i8-3 ">
<a href="/xyfg/list.htm" title="校园风光" target="_self"><span class="item-name">校园风光span>a><i class="mark">i>
li>
ul>
li>
<li class="nav-item i9 ">
<a href="/46/list.htm" title="校园服务" target="_self"><span class="item-name">校园服务span>a><i class="mark">i>
<ul class="sub-nav">
<li class="nav-item i9-1 ">
<a href="/275/list.htm" title="学校校历" target="_self"><span class="item-name">学校校历span>a><i class="mark">i>
li>
<li class="nav-item i9-2 ">
<a href="http://tsgapp.cswu.cn" title="图情服务" target="_blank"><span class="item-name">图情服务span>a><i class="mark">i>
li>
<li class="nav-item i9-3 ">
<a href="ftp://ftp.cqcmc.cn/" title="软件下载" target="_blank"><span class="item-name">软件下载span>a><i class="mark">i>
li>
<li class="nav-item i9-4 ">
<a href="http://hygl.cswu.cn:8080/" title="会议管理" target="_blank"><span class="item-name">会议管理span>a><i class="mark">i>
li>
<li class="nav-item i9-5 ">
<a href="/280/list.htm" title="电话查询" target="_self"><span class="item-name">电话查询span>a><i class="mark">i>
li>
<li class="nav-item i9-6 ">
<a href="http://dzb.cswu.cn/dzb/yd/index.asp" title="邮递查询" target="_blank"><span class="item-name">邮递查询span>a><i class="mark">i>
li>
ul>
li>
<li class="nav-item i10 ">
<a href="/47/list.htm" title="办事流程" target="_self"><span class="item-name">办事流程span>a><i class="mark">i>
li>
ul>
div>
div>
div>
div>
div>
<div class="banner" frag="面板28">
<div class="inner" frag="窗口28">
<script language="JavaScript" class="" >
var w28imgJsons = [
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<div class="wrapper contain_bg" id="container">
<div class="inner" frag="面板43">
<div class="post post-43 mbox" frag="窗口43">
<div class="tt">
<h3 class="tit">
<span class="title" frag="标题" title="综合新闻"> 综合新闻span>
h3>
<div class="more_btn">
<span class="more_text"><a href="/34/list.htm">更多a>span>
div>
div>
<div class="con">
<div id="wp_news_w43">
<ul class="news_list clearfix">
<li class="news news_li n1 clearfix">
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<div class="news_con">
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