如何从下拉列表中选择选项标签？ [英] How get selected option label from a dropdown list?

问题描述

我正在开发一个简单的Web应用程序，其中我想在下一个JSP页面的HTML页面中选择一个下拉列表的选项标签。我使用MVC模式，因此Servlet作为控制器将重定向（转发）请求到JSP视图。

I am developing a simple web application in which I want to take the option label of a dropdown list in HTML page on the next JSP page. I am using MVC pattern and thus Servlet as a controller will be redirecting (forwarding?) the request to JSP view.

request.getParameter ）给我只有选项值。但在我的情况下，期权价值和标签是不同的。如何获取选项标签？

The request.getParameter() gives me only the option value. But in my case the option value and label are different. How can I get the option label?

推荐答案

您需要在服务器端维护选项值和标签的映射。例如。里面一些 ServletContextListener 或者servlet的 init（）：

You need to maintain a mapping of option values and labels in the server side. E.g. inside some ServletContextListener or perhaps servlet's init():

Map<String, String> countries = new LinkedHashMap<String, String>();
countries.put("CW", "Curaçao");
countries.put("NL", "The Netherlands");
countries.put("US", "United States");
// ...

servletContext.setAttribute("countries", countries);

当您将其作为 $ {countries} ，那么你可以显示如下：

When you put it in the application scope as ${countries}, then you can display it as follows:

<select name="country">
  <c:forEach items="${countries}" var="country">
    <option value="${country.key}">${country.value}</option>
  </c:forEach>
</select>

这样您就可以在服务器端获取标签，如下所示：

This way you will be able to obtain the label in the server side as follows:

Map<String, String> countries = (Map<String, String>) getServletContext().getAttribute("countries");
// ...

String countryCode = request.getParameter("country");
String countryName = countries.get(countryCode);
// ...

或在JSP中显示纯文本：

Or to display plain in JSP:

<p>Country code: ${param.country}</p>
<p>Country name: ${countries[param.country]}</p>

或者预先选择下拉列表：

Or to pre-select the dropdown:

<select name="country">
  <c:forEach items="${countries}" var="country">
    <option value="${country.key}" ${param.country == country.key ? 'selected' : ''}>${country.value}</option>
  </c:forEach>
</select>

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