Using Spring MVC 3.1+ WebApplicationInitializer to programmatically configure session-config and error-page

Question

WebApplicationInitializer provides a way to programmatically represent a good portion of a standard web.xml file - the servlets, filters, listeners.

However I have

Answer 1

Using spring-boot it's pretty easy.

I am sure it could be done without spring boot as well by extending SpringServletContainerInitializer. It seems that is what it is specifically designed for.

Servlet 3.0 ServletContainerInitializer designed to support code-based configuration of the servlet container using Spring's WebApplicationInitializer SPI as opposed to (or possibly in combination with) the traditional web.xml-based approach.

Sample code (using SpringBootServletInitializer)

public class MyServletInitializer extends SpringBootServletInitializer {

    @Bean
    public EmbeddedServletContainerFactory servletContainer() {
        TomcatEmbeddedServletContainerFactory containerFactory = new TomcatEmbeddedServletContainerFactory(8080);

        // configure error pages
        containerFactory.getErrorPages().add(new ErrorPage(HttpStatus.UNAUTHORIZED, "/errors/401"));

        // configure session timeout
        containerFactory.setSessionTimeout(20);

        return containerFactory;
    }
}