not hit default page after Single sign on preauthentication filter(Apache+Tomcat+SpringSecurity)

Question

I have one working Spring web application deployed on tomcat, using Spring Security to do authentication and authorization. My new requirement is using SSO via apache http request to tomcat.

I got this working using the preauthentication filter and get authorization through LDAP server( MS AD). The problem is the default page is not opened automatically. it's working when I type in the URl like http://localhost/postLogin.sp. Here is the security.xml

<http use-expressions="true"  entry-point-ref="http403ForbiddenEntryPoint">
        <custom-filter position="PRE_AUTH_FILTER" ref="ssoPreAuthenticationFilter" />
       <!-- other static assets skip -->
        <intercept-url pattern="/**" access="hasRole('ROLE_USER')" />

        <!--<form-login authentication-failure-url="/loginForm.jsp?failure=true"  default-target-url='/postLogin.sp' always-use-default-target='true' />-->

    </http>

I comment out the , because using ssoPreAuthenticationFilter as preauthentication filter. but where is could setup this default page "postLogin.sp". The authentication-success-handler-ref is part of , so it's not useful here.

I have welcome-file-list configured as below

 <welcome-file-list>
  <welcome-file>/postLogin.sp</welcome-file>
 </welcome-file-list>
    <servlet-mapping>
   <servlet-name>defaultServlet</servlet-name>
   <url-pattern>/</url-pattern>
 </servlet-mapping>

So please help.