[SOLVED] Not able to view ActionMessages in my JSP and problems with validation in Struts 2

I am having various problems with my code:

I am not able to view my ActionMessages and ActionErrors set by LoginAction
Once I log in, if I again go to URL: /login, it does not redirect me to success page.

EDIT:

I am able to redirect successfully now if the session alreay exists. I had to make 2 changes that i figured out:

Firstly, in my action class I was setting session variables in void setSession(Map map) which was wrong( It should only be a setter function).
Secondly, I checked if the session variable exists in my validate() method which solved the problem.

But I am still not able to view my ActonErrors and ActionMessages.
Is it necessary to use <s:form>. Because it disturbs my CSS and I am not able to find solutions to correct that. Can I assign ID attribute in <s:form> ?

Following is my JSP code:

...
        <s:if test="hasActionErrors()">
            <div id="errorMessage"><s:actionerror /></div>
        </s:if>
        <s:if test="hasActionMessages()">
            <div id="errorMessage"> <s:actionmessage /></div>
        </s:if>
        <form action="login" method="POST" id="login-form">
            <fieldset>
                <p>
                    <label for="loginUserName">username</label>
                    <input type="text" id="loginUserName" maxlength="10" placeholder="Eg. EMP0000000" 
                    title="User ID is of format EMP0000000" pattern="(EMP)([0-9]{7})" required
                     name="loginUserName" class="round full-width-input" autofocus />
                </p>

                <p>
                    <label for="loginPassword">password</label>
                    <input type="password" name="loginPassword" maxlength="20" id="loginPassword" required 
                    class="round full-width-input" />
                </p>
                
                <p>I've <a href="#">forgotten my password</a>.</p>
                
                <input type="submit" class="button round blue image-right ic-right-arrow" value="LOG IN" />

            </fieldset>

        </form>
...

Here is my struts.xml:

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE struts PUBLIC
"-//Apache Software Foundation//DTD Struts Configuration 2.0//EN"
"http://struts.apache.org/dtds/struts-2.0.dtd">
        
<struts>
        <constant name="struts.enable.DynamicMethodInvocation" value="false" />
        <constant name="struts.devMode" value="false" />

        <package name="employee" extends="struts-default" namespace="/">

            <interceptors>
                <interceptor name="login" class="com.sreebhog.interceptors.LoginInterceptor" />
        
                <interceptor-stack name="loginStack">
                    <interceptor-ref name="login" ></interceptor-ref>
                    <interceptor-ref name="defaultStack" ></interceptor-ref>
                </interceptor-stack>
            </interceptors>
                <default-interceptor-ref name="loginStack"></default-interceptor-ref>
            <global-results>
                <result name="loginRedirect">/login </result>
            </global-results>
        
            <action name="login" class="com.sreebhog.actions.LoginAction">
                <result name="input">/JSP/sreebhog_login.jsp</result>
                <result name="success">/JSP/index.jsp</result>
            </action>
            <action name="logout" class="com.sreebhog.actions.LogoutAction">
                <result name="logout">/JSP/sreebhog_login.jsp</result>
            </action>
        </package>


</struts>

Here is my LoginAction:

package com.sreebhog.actions;

import java.io.UnsupportedEncodingException;
import java.security.NoSuchAlgorithmException;
import java.util.Map;

import org.apache.struts2.dispatcher.SessionMap;
import org.apache.struts2.interceptor.SessionAware;

import com.opensymphony.xwork2.ActionSupport;
import com.sreebhog.dao.EmployeeDAO;
import com.sreebhog.interfaces.LoginRequired;
import com.sreebhog.model.dto.Employee;
import com.sreebhog.utility.Cryptography;

public class LoginAction extends ActionSupport implements SessionAware,LoginRequired {
    
    private String loginUserName;
    private String loginPassword;
    
    SessionMap<String,Object> sessionMap;
    
    @SuppressWarnings({ "unchecked", "rawtypes" })
    @Override
    public void setSession(Map map) {
        sessionMap=(SessionMap) map;
        sessionMap.put("username", loginUserName);
    }
        
    public String execute()
    {
        String userName = null;
          if (sessionMap.containsKey("username"))
          { 
              userName = (String) sessionMap.get("username");
              if (userName != null )
              {
                  if (!userName.equals(""))
                  {
                      return SUCCESS;
                  }
              }
          }
          
        EmployeeDAO employeeDao = new EmployeeDAO();
        Employee employee = employeeDao.find(this.getLoginUserName());
        if (employee == null || employee.getUserName().equals(""))
        {
            System.out.println("Here1");
            addActionError("Username or password is invalid");
            return INPUT;
        } else
            try {
                if (employee.getPassword().equals(Cryptography.getHash("SHA-1", this.getLoginPassword(), employee.getSalt())))
                {
                    System.out.println("Here2");
                    addActionError("Username or password is invalid");
                    return INPUT;
                }
                else {
                    System.out.println("Here3");
                    sessionMap.put("username",(String)loginUserName);
                    sessionMap.put("role",(String)employee.getPermissions().getRole());
                    return SUCCESS;
                }
            } catch (NoSuchAlgorithmException | UnsupportedEncodingException e) {
                e.printStackTrace();
            }
        return INPUT;
    }
    
    public void validate()
    {
        
        if (loginUserName == null || loginUserName.equals("") || loginPassword == null || loginPassword.equals(""))
        {
            addActionError("Please fill in username and password");
        }
    }

    public String logout()
    {
        sessionMap.invalidate();
        return INPUT;
    }

    public String getLoginUserName() {
        return loginUserName;
    }

    public void setLoginUserName(String loginUserName) {
        this.loginUserName = loginUserName;
    }

    public String getLoginPassword() {
        return loginPassword;
    }

    public void setLoginPassword(String loginpassword) {
        this.loginPassword = loginpassword;
    }

}

Here is my LoginInterceptor:

package com.sreebhog.interceptors;

import java.util.Map;

import com.opensymphony.xwork2.ActionContext;
import com.opensymphony.xwork2.ActionInvocation;
import com.opensymphony.xwork2.interceptor.AbstractInterceptor;
import com.sreebhog.actions.LoginAction;
import com.sreebhog.interfaces.LoginRequired;

public class LoginInterceptor extends AbstractInterceptor {

    @Override
    public String intercept(final ActionInvocation invocation) throws Exception {
        Map<String, Object> session = ActionContext.getContext().getSession();
        String userName = (String) session.get("username");

        if (userName != null && !userName.equals("")) {
            return invocation.invoke();
        }

        Object action = invocation.getAction();

        if (!(action instanceof LoginRequired)) {
            return invocation.invoke();
        }

        if (!(action instanceof LoginAction)) {
            return "loginRedirect";
        }

        return invocation.invoke();
    }
}