Bootstrap的引用方法分为两种：1）将Bootstrap下载到本地引用 2）在线引用Bootstrap
引用方法
1）
将Bootstrap下载到桌面然后解压缩（当然你可以将解压缩的Bootstrap文件放到任意位置，但是解压缩的Bootstrap文件必须和HTML在同一目录下），我自己写的HTML文件也在桌面上，我下载的是bootstrap-3.3.7-dist。
解压缩后的bootstrap-3.3.7-dist
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<meta name="viewport" content="width=device-width, initial-scale=1">
<meta charset="UTF-8">
<title>将bootstrap引入html文件中</title>
<link href="bootstrap-3.3.7-dist/css/bootstrap.min.css" rel="stylesheet">
<!--<link rel="stylesheet" href="https://cdn.bootcss.com/bootstrap/3.3.7/css/bootstrap.min.css" integrity="sha384-BVYiiSIFeK1dGmJRAkycuHAHRg32OmUcww7on3RYdg4Va+PmSTsz/K68vbdEjh4u" crossorigin="anonymous">-->
</head>
<body>
<div class="col-md-3">abcdefg</div>
<div class="col-md-3">abcdefg</div>
<div class="col-md-3">abcdefg</div>
<div class="col-md-3">abcdefg</div>
helloword
</body>
</html>
2）在线引用
在Boostrap官网http://v3.bootcss.com/getting-started/#download
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<meta name="viewport" content="width=device-width, initial-scale=1">
<meta charset="UTF-8">
<title>将bootstrap引入html文件中</title>
<!--<link href="bootstrap-3.3.7-dist/css/bootstrap.min.css" rel="stylesheet">-->
<link rel="stylesheet" href="https://cdn.bootcss.com/bootstrap/3.3.7/css/bootstrap.min.css" integrity="sha384-BVYiiSIFeK1dGmJRAkycuHAHRg32OmUcww7on3RYdg4Va+PmSTsz/K68vbdEjh4u" crossorigin="anonymous">
</head>
<body>
<div class="col-md-3">abcdefg</div>
<div class="col-md-3">abcdefg</div>
<div class="col-md-3">abcdefg</div>
<div class="col-md-3">abcdefg</div>
helloword
</body>
</html>
引入ok看看效果
