如何在 jsp 页面的下拉菜单中显示值？

Question

我有一个下拉菜单，当 select 从菜单中选择一个项目时，我想在下面显示它。这是我的 jsp:

<body>
        <select name="courseSelect">
            <c:forEach  var="course" items="${courses}">         
                <option name="courseOption" value="${course.name}">${course.name}</option>   
            </c:forEach>
        </select>
             ${courseSelect} //for example to show it here
    </body>

这是我的 servlet：

   protected void doGet(HttpServletRequest request, HttpServletResponse response)
        throws ServletException, IOException {
    HttpSession session = request.getSession(true);
    String courseSelect = request.getParameter("courseSelect");
    session.setAttribute("courseName", courseSelect);
    session.setAttribute("courses", Course.allCourses());
    RequestDispatcher rd = request.getRequestDispatcher("home.jsp");
    rd.forward(request, response);
}

我试图从 select 标签和选项标签中获取参数，但它没有显示任何内容。我该如何解决？

Answer 1

Javascript 可能更适合在前端处理这种情况 itself.you 可以将您的代码更改为 Vanilla Javascript

    <body>
        <select id="selectBox" name="courseSelect" onchange="changeText()">
            <c:forEach  var="course" items="${courses}">         
                <option name="courseOption" value="${course.name}">${course.name}</option>   
            </c:forEach>
        </select>
             <p id="showValue"></p> //for example to show it here
    <script>
   function changeText(){
     var selectedValue = document.getElementById('selectBox').value;
     document.getElementById('showValue').innerText = selectedValue;
   }
</script>
    </body>

如何在 jsp 页面的下拉菜单中显示值？

How to show value from dropdown menu in jsp page?

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