To apply an interceptor that will monitor and evaluate the /login.html request:

1. Let us create a class of HandlerInterceptor type that keeps track of the access time of each user:

public class LoginInterceptor implements     
    HandlerInterceptor{ 
 
@Override 
public void afterCompletion(HttpServletRequest request,  
  HttpServletResponse response, Object handler,  
Exception ex) throws Exception { 
         System.out.println("INFO LOG ......  
       Fully Done login transaction....."); 
} 
 
@Override 
public boolean preHandle(HttpServletRequest request,  
  HttpServletResponse response, Object handler) 
    throws Exception { 
System.out.println("INFO LOG ......  
Beginning login transaction....."); 
Long startLog = System.currentTimeMillis(); 
Cookie startTime = new Cookie("startLog", 
   startLog.toString()); 
response.addCookie(startTime); 
System.out.println("INFO LOG ......  
Done Computing Start Time....."); 
return true; 
} 
 
@Override 
public void postHandle(HttpServletRequest request,  
  HttpServletResponse response, Object handler, 
ModelAndView modelAndView) throws Exception { 
System.out.println("INFO LOG ......  
       User Successfuly logged in.....");   
 } 
} 

The interface org.springframework.web.servlet.HandlerInterceptor has been used to implement the three helper methods, namely preHandle(), postHandle(), and afterCompletion().

2. Implement another interceptor using the class org.springframework.web.servlet.handler.HandlerInterceptorAdapter, whose task is to audit the time duration the user has spent with the application. This component also logs the end of the whole MVC transactions:

public class AfterLogoutInterceptor extends  
  HandlerInterceptorAdapter{ 
   
  @Override 
  public boolean preHandle(HttpServletRequest request, 
     HttpServletResponse response, Object handler) 
      throws Exception { 
     
System.out.println("INFO LOG ......  
Entering After Logout transaction....."); 
   Long startLog = null; 
   Cookie[] allCookies = request.getCookies(); 
   for(Cookie c : allCookies){ 
      if(c.getName().equalsIgnoreCase("startLog")){ 
        startLog = Long.parseLong(c.getValue()); 
        System.out.println(c.getValue()); 
        break; 
      } 
    } 
   long elapsed = System.currentTimeMillis() -  
          startLog.longValue(); 
   System.out.println("----------Time Elapsed: " +  
        (elapsed/1000) + " sec ---------------"); 
   return true; 
  } 
   
  @Override 
  public void afterCompletion(HttpServletRequest request,  
    HttpServletResponse response, Object handler,  
      Exception ex) throws Exception { 
      System.out.println("INFO LOG ......  
        Fully Done Logout transaction....."); 
  } 
} 

3. To make the interceptors work, open the root context SpringDispatcherConfig and override the addInterceptors() to register the two custom interceptors, LoginInterceptor and AfterLogoutInterceptor:

@Override 
public void addInterceptors(InterceptorRegistry registry) { 
  registry.addInterceptor( 
new LoginInterceptor()).addPathPatterns("/login.html"); 
  registry.addInterceptor( 
new AfterLogoutInterceptor()) 
.addPathPatterns("/after_logout.html*"); 
} 

4. Save all files. Clean, build, and deploy the ch04 project.