JSP中Bootstrap下拉列表无法展开的问题求助

你的下拉列表无法显示选项，核心原因是只引入了Bootstrap的CSS文件，没有加载Bootstrap的JavaScript和Popper.js——Bootstrap 5的下拉组件依赖这两个JS文件来实现点击展开/收起的交互逻辑。

修复后的完整代码 #

<%@page contentType="text/html" pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>  

<head>
        <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
        <title>JSP Page</title>
        <link href="https://cdn.jsdelivr.net/npm/bootstrap@5.3.2/dist/css/bootstrap.min.css" rel="stylesheet" integrity="sha384-T3c6CoIi6uLrA9TneNEoa7RxnatzjcDSCmG1MXxSR1GAsXEV/Dwwykc2MPK8M2HN" crossorigin="anonymous">
    </head>
    <body class="bg-primary bg-opacity-75">
        <header>
        <div class="row align-items-center">
            <div class="col">
                <img class="img-fluid m-3" src="images/logo.jpg" style="max-height: 400px; max-height:100px"/><br>
            </div>
        </div>
            <div class="row">
            <div class="col">
                <form action="SvMenu" method="GET">

                <nav class="navbar navbar-expand-lg bg-body-tertiary" data-bs-theme="dark">
                <div class="container-fluid justify-content-end">   
                  <a class="navbar-brand" href="#">MENU DE OPCIONES</a>
                  <button class="navbar-toggler" type="button" data-bs-toggle="collapse" data-bs-target="#navbarSupportedContent" aria-controls="navbarSupportedContent" aria-expanded="false" aria-label="Toggle navigation">
                    <span class="navbar-toggler-icon"></span>
                  </button>
                  <div class="collapse navbar-collapse" id="navbarSupportedContent">
                    <ul class="navbar-nav me-auto mb-2 mb-lg-0">
                      <li class="nav-item">
                        <a class="nav-link" aria-current="page" href="#">Inicio</a>
                      </li>
                      <li class="nav-item">
                        <a class="nav-link" href="#">Modulo de facturas</a>
                      </li>
                      <li class="nav-item">
                        <a class="nav-link" href="#">Modulo de clientes</a>
                      </li>
                      <li class="nav-item dropdown">
                            <a class="nav-link dropdown-toggle" href="#" role="button" data-bs-toggle="dropdown" aria-expanded="false">
                              Dropdown
                            </a>
                            <ul class="dropdown-menu">
                              <li><a class="dropdown-item" href="#">Action</a></li>
                              <li><a class="dropdown-item" href="#">Another action</a></li>
                              <li><a class="dropdown-item" href="#">Something else here</a></li>
                            </ul>
                       </li>
                    </ul>
                  </div>
                </div>
              </nav>
              </form> 
            </div>
        </div>
        </header>
        
        <!-- 新增：引入Bootstrap依赖的JS文件 -->
        <script src="https://cdn.jsdelivr.net/npm/@popperjs/core@2.11.8/dist/umd/popper.min.js" integrity="sha384-I7E8VVD/ismYTF4hNIPjVp/Zjvgyol6VFvRkX/vR+Vc4jQkC+hVqc2pM8ODewa9r" crossorigin="anonymous"></script>
        <script src="https://cdn.jsdelivr.net/npm/bootstrap@5.3.2/dist/js/bootstrap.min.js" integrity="sha384-BBtl+eGJRgqQAUMxJ7pMwbEyER4l1g+O15P+16Ep7Q9Q+zqX6gSbd85u4mG4QzX+" crossorigin="anonymous"></script>
    </body>
</html>

关键说明 #

• Bootstrap 5的所有交互组件（下拉、模态框、折叠等）都需要依赖Popper.js处理定位，以及Bootstrap自身JS实现交互逻辑。
• 必须按照Popper.js → Bootstrap JS的顺序引入，否则会出现功能异常。

内容的提问来源于stack exchange，提问作者FabianRosero18