1、配置环境
（1）Bootstrap下载：https://v5.bootcss.com/docs/getting-started/download/
（2）下载后需要其中的：bootstrap.css和bootstrap.js文件分别放到css和js文件中。
（3）引入配置文件：
<link rel="stylesheet" href="css/bootstrap.css">
<script src="js/bootstrap.js"></script>2、代码如下
<!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=1.0">
<title>欢迎登陆</title>
<link rel="stylesheet" href="css/bootstrap.css">
<script src="js/bootstrap.js"></script>
<style>
body {
background-color: rgb(240, 233, 234);
}
h2 {
text-align: center;
}
</style>
</head>
<body>
<div class="container col-4 mt-5">
<form action="#" class="needs-validation" novalidate>
<div class="mb-3 ">
<h2>欢迎登陆</h2>
</div>
<div class="mb-3 ">
<label for="formGroupExampleInput " class="form-label "><strong>邮箱</strong></label>
<input type="text " class="form-control " id="formGroupExampleInput " placeholder="123123 " required>
<div class="invalid-feedback ">邮箱错误</div>
</div>
<div class="mb-3 ">
<label for="formGroupExampleInput2 " class="form-label "><strong>密码</strong></label>
<input type="text " class="form-control " id="formGroupExampleInput2 " placeholder="Password " required>
<div class="invalid-feedback ">密码错误</div>
</div>
<div class="form-check ">
<input class="form-check-input " type="radio" id="gridCheck " name="gridCheck">
<label class="form-check-label " for="gridCheck ">记住</label>
</div>
<div class="d-grid gap-2 mx-auto ">
<button class="btn btn-success " type="button ">Button</button>
</div>
</form>
</div>
<script>
// Example starter JavaScript for disabling form submissions if there are invalid fields
(function() {
'use strict'
// Fetch all the forms we want to apply custom Bootstrap validation styles to
var forms = document.querySelectorAll('.needs-validation')
// Loop over them and prevent submission
Array.prototype.slice.call(forms)
.forEach(function(form) {
form.addEventListener('submit', function(event) {
if (!form.checkValidity()) {
event.preventDefault()
event.stopPropagation()
}
form.classList.add('was-validated')
}, false)
})
})()
</script>
</body>
</html>3、效果展示
