java - 当获取 request.getParameter (""时，字符串无法转换为 ArrayList )

Question

从另一个jsp中以request.getParameter("")的形式获取jsp中的列表值

a.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();

             %>

提前非常感谢

Answer 1

您可以以数组形式检索值:

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

这些值应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>