我收到此错误，无法弄清楚问题可能出在哪里。“用户ID”列在数据库中，并且在Bean中。有谁有想法吗？

org.apache.jasper.JasperException: An exception occurred processing JSP page /user.jsp     at line 24

21:   
22:     <form method="POST" action="AdminServlet" name="frmAddUser">  
23:         User ID : <input type="text" readonly="readonly" name="userid"  
24:             value="<c:out value="${user.userid}" />" />   
Username : <input  
25:             type="text" name="firstName"  
26:             value="<c:out value="${user.firstName}" />" />   
LastName : <input  
27:             type="text" name="lastName"

root cause

javax.el.PropertyNotFoundException: Property 'userid' not found on type java.lang.String

谢谢。