java - Spring security check the user is logged or not when click a button -

i'm creating simple web application online flight reservation system using spring mvc spring security. i've created following table show flight details.

<table class="table table-bordered table-hover table-striped ">     <thead>         <tr>             <th>flight no</th>             <th>flight destination</th>             <th>flight origin</th>             <th>flight date</th>             <th>flight time</th>             <th>book now</th>         </tr>     </thead>      <tbody>         <form:form commandname="reserv" cssclass="form-horizontal">             <c:foreach items="${flightinfos}" var="flightinfo">                 <tr>                     <td>${flightinfo.flightno}</td>                     <td>${flightinfo.destination}</td>                     <td>${flightinfo.origin}</td>                     <td>${flightinfo.flightdate}</td>                     <td>${flightinfo.flighttime}</td>                     <td><input type="submit" value="book now" class="btn btn-primary"></td>                 </tr>             </c:foreach>         </form:form>     </tbody> </table> 

in table, want check user logged or not when user click on "book now" button. means can see page need log system book flight. here security.xml file.

<http use-expressions="true">     <intercept-url pattern="/users**" access="hasrole('role_admin')" />     <intercept-url pattern="/users/**" access="hasrole('role_admin')" />     <intercept-url pattern="/account**" access="hasrole('role_user')" />     <intercept-url pattern="/reservation**" access="hasrole('role_user')" />     <form-login login-page="/login.html"/>     <csrf disabled="true"/>     <logout logout-url="/logout" /> </http> 

how can check whether user logged or not, when clicks on "book now" button ? there simple way ?

"how can check whether user logged or not, when clicks on "book now" button ? there simple way ?"

when submit button pressed; form posted url have given (as post) example:

<form action="/myurl" method="post"> first name: <input type="text" name="fname"><br> last name: <input type="text" name="lname"><br> <input type="submit" value="submit"> </form>  

just change url restricted in security xml. like:

<intercept-url pattern="/postformurl" access="hasrole('role_user')" /> 

then when controller mapping of formurl ; there if passed spring security.