How to use session in JSP pages to get information?

Question

I have a JSP page used for editing some user's info. When a user logins to the website, I keep the information in the session, then in my edit page I try the following:

<%! String username=session.getAttribute("username"); %> <form action="editinfo" method="post">     <table>         <tr>             <td>Username: </td><td> <input type="text" value="<%=username %>" /> </td>         </tr>     </table> </form> 

but it gives error saying session cannot be resolved. What can I do about it?

Answer 1

JSP implicit objects likes session, request etc. are not available inside JSP declaration <%! %> tags.

You could use it directly in your expression as

<td>Username: </td> <td><input type="text" value="<%= session.getAttribute("username") %>" /></td> 

On other note, using scriptlets in JSP has been long deprecated. Use of EL (expression language) and JSTL tags is highly recommended. For example, here you could use EL as

<td>Username: </td> <td><input type="text" value="${username}" /></td> 

The best part is that scope resolution is done automatically. So, here username could come from page, or request, or session, or application scopes in that order. If for a particular instance you need to override this because of a name collision you can explicitly specify the scope as

<td><input type="text" value="${requestScope.username}" /></td> or, <td><input type="text" value="${sessionScope.username}" /></td> or, <td><input type="text" value="${applicationScope.username}" /></td> 

Answer 2

Use

<% String username = (String)request.getSession().getAttribute(...); %> 

Note that your use of <%! ... %> is translated to class-level, but request is only available in the service() method of the translated servlet.

See how JSP code is translated to a servlet.