html - 记住jsp文件中的下拉选择

Question

我在 jsp 文件中有一个下拉列表

<select name="PID" id="PID" style="min-width: 100px;" >

<% 
for(somelist pm : List) { %>
<option value="<%=pm.getsmthing()%>" selected><%=pm.getName()%></option>
<option  value="-1">Select a Property</option>

这是在一个表格里面。我想在提交表单后记住选定的项目名称。

Answer 1

Just print selected conditionally whenever the associated request parameter has exactly the same value.

<option value="<%=pm.getsmthing()%> <%=(pm.getsmthing().equals(request.getParameter("PID")) ? "selected" : "")%>><%=pm.getName()%></option>

Do not store it in the session. It would affect all pages in all browser tabs/windows in the same session which may result in "wtf?" experiences of the enduser.

---

Unrelated to the concrete problem, that's pretty an oldschool way of writing JSPs. Learn JSTL and EL. Your code would then look like this:

<select name="PID" id="PID" style="min-width: 100px;">
  <c:forEach items="${List}" var="pm">
    <option value="${pm.smthing}" ${pm.smthing == param.PID ? 'selected' : ''}>${pm.name}</option>
    <option value="-1">Select a Property</option>
  </c:forEach>
</select>

Answer 2

将您选择的值添加到 HTTP 会话并在您需要显示表单时随时检索它。