Accessing request scoped bean inside servlet

Question

I have a jsp page where i am using a bean as request scope bean. I have an input text whose value is the attribute of the bean. On the form submit my action is someServlet. Now in that someServlet i want to access the bean that i used in my jsp page. here is sample code i am using.

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title here</title>
</head>
<body>
<jsp:useBean id="userBean" scope="request" class="com.iceman.bean.UserBean">
<jsp:setProperty property="*" name="userBean"/></jsp:useBean>
    <form action="action.do" method="post">
        Type Your Name:<input type="text" name="userName"/><br/>
        <input type="submit" value="Submit"/> 
    </form>
</body>
</html>

Servler

protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
        UserBean userBean = (UserBean)request.getAttribute("userBean");
        response.getWriter().print(userBean.getUserName());
    }

When i run this i get a null pointer exception on servlet line where i call bean getter method.

Where am i doing wrong?

[Accessing request scoped bean](http://stackoverflow.com/questions/15907391/accessing-request-scoped-bean) ? — Perdomoff, Dec 26 '15 at 06:19

score 2 · Accepted Answer · answered Dec 26 '15 at 08:18

2

It is simply because the render request and the post request are different requests:

client sends a first request, and server side a jsp is used to build a response. Request scope beans created in JSP exist only in that one
user fills in the form and posts a new requests

The only ways to have information to persist between requests are:

the session (and the flash that is provided by some frameworks like ruby on rails or Spring MVC)
form fields (including hidden ones)
URL parameters

answered Dec 26 '15 at 08:18

Serge Ballesta

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so i can't get access to request bean from servlet? – Usman Riaz Dec 26 '15 at 09:11
@UsmanRiaz : you can, in **same** request. If you called a servlet with include or forward, you could have access to request scoped beans. – Serge Ballesta Dec 26 '15 at 10:16
I am just submitting a form and expecting the bean from this request in servlet :-( – Usman Riaz Dec 26 '15 at 10:32

score 0 · Answer 2 · edited May 23 '17 at 10:27

0

For clarity , you need to take your bean declaration <jsp:useBean id="userBean" scope="request" class="com.iceman.bean.UserBean"></jsp:useBean> outside form element , and change definition to

<jsp:useBean id="userBean" scope="request" class="com.iceman.bean.UserBean">
<jsp:setProperty name="userBean" property="*" />
</jsp:useBean>

Star ( * ) means that all bean properties with names that match request parameters sent to the page are set automatically. ( As per O`Reilly book )

then you need to change line <input type="text" value="${userBean.userName}"/> to <input type="text" name="one of field names as per your UserBean class "/>

You have not shared details of UserBean class but I guess field name is userName

Regarding bean being NULL in request , please refer answer by Jan Zyka for question jsp useBean is NULL by getAttribute by servlet

Hope it helps !!

edited May 23 '17 at 10:27

Community

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answered Dec 26 '15 at 06:34

Sabir Khan

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Thanks for your kind answer @Sabir Khan. I am still not able to get bean from request in servlet. i have edited my code as per your answer. kindly take a look – Usman Riaz Dec 26 '15 at 07:07
your `` is outside `` tag , that needs to be inside. – Sabir Khan Dec 26 '15 at 07:10
It's inside now but still getting null pointer exception in servlet – Usman Riaz Dec 26 '15 at 07:14
try adding `<%@page import="com.iceman.bean.UserBean"%>` in your jsp – Sabir Khan Dec 26 '15 at 07:18
well i am using fully qualified name in class attribute, i did it anyway but error still there? can you please take a look at my servlet code above? i think there must be something missing. – Usman Riaz Dec 26 '15 at 07:22
if bean is found in statement `UserBean userBean = (UserBean)request.getAttribute("userBean");`, that means bean is present in request scope but not instantiated, which means some issue on jsp side. Is that the case? – Sabir Khan Dec 26 '15 at 07:31
I don't think so. You can always call getAttribute(name). if there is some value it will not be null. i just checked the bean if it were null. It is null. that means bean is not in request. You can call getAttribute("anyting") and cast it to bean. That does'nt matter. – Usman Riaz Dec 26 '15 at 07:39
I think your problem is answer by Jan Zyka for question [jsp useBean is NULL by getAttribute by servlet](http://stackoverflow.com/questions/5027160/jsp-usebean-is-null-by-getattribute-by-servlet). Also we do get "bean [name] not found within scope" message is bean is not present, not sure if your case is any different. – Sabir Khan Dec 26 '15 at 07:40

Accessing request scoped bean inside servlet

2 Answers2