字符串无法转换为 ArrayList<String> 当获取为 request.getParameter(&quot; &quot;)

Question

从另一个jsp获取jsp中的List值作为request.getParameter("")

一个.jsp

List<String> abc = 
 (ArrayList<String>)request.getAttribute("studentsrollno");// got 
  studentsrollno from servlet by request.setAttribute();

   <form action="b.jsp" method="post">
       <input type="hidden" name="rollno" value="<%=abc%>"/>

            <input type="submit">
   </form>

b.jsp

         <%
   List<String> a2 = (ArrayList<String>) request.getParameter("rollno");// 
 getting error string cannot be converted to ArrayList<String> // How can I 
 display data rollno here ?

  // Iterator<String> itr = a2.iterator();

             %>

提前谢谢了

Answer 1

您可以将值作为数组检索：

String[] vals = request.getParameterValues("rollno");

这些值应该作为单独的表单参数发出：

<c:foreach items="${abc}" var="item">
    <input type="hidden" name="rollno" value="${fn:escapeXml(item)}" />
</c:foreach>