How to define and in servlet 3.0's web.xml-less?

Question

I have existing web-app which I want to convert into web.xml-less of servlet's 3.0. I've managed to make it working, however there are 2 tags in web.xml which I still don't know the equivalent code in web.xml-less environment.

<welcome-file-list>
    <welcome-file>/index.jsp</welcome-file>
</welcome-file-list>

<error-page>
    <error-code>404</error-code>
    <location>/pageNotFound</location>
</error-page>

Any help is appreciated

Answer 1

In Servlets 3.0 you don't need a web.xml for many cases, however, sometimes it's required or just useful. Your case is just one of them - there is no special annotations to define welcome-file list or error-pages.

Another thing is - would you really like to have them hardcoded? There are some valid use-cases for annotation / programmatic based configuration and for declarative configuration in XML. Moving to Servlets 3.0 doesn't necessarily means getting rid of web.xml at all cost.

I would find the entries you posted a better example of configuration in XML. Firstly - they can be changed from deployment to deployment and secondly - they affect whole application and not any particular Servlet.

Answer 2

For analog welcome-page-list put this in

@EnableWebMvc
@Configuration
@ComponentScan("com.springapp.mvc")
public class MvcConfig extends WebMvcConfigurerAdapter {
...
    @Override
    public void addResourceHandlers(ResourceHandlerRegistry registry) {
        registry.addResourceHandler("/*.html").addResourceLocations("/WEB-INF/pages/");
    }

    @Override
    public void addViewControllers(ViewControllerRegistry registry) {
        registry.addViewController("/").setViewName("forward:/index.html");
    }
...
}

Answer 3

In Spring Boot or general Spring MVC app for following scenario:

Static files can be served from locations registered with a custom ResourceHandlerRegistry. We have a static resource index.html and it can accessed at localhost:8080/index.html. We want to just redirect localhost:8080/ request to localhost:8080/index.html, following code will can be used.

package in.geekmj.config;

import org.springframework.context.annotation.Configuration;

import org.springframework.web.servlet.config.annotation.EnableWebMvc;

import org.springframework.web.servlet.config.annotation.ResourceHandlerRegistry;

import org.springframework.web.servlet.config.annotation.ViewControllerRegistry;

import org.springframework.web.servlet.config.annotation.WebMvcConfigurerAdapter;

@Configuration
@EnableWebMvc
public class WebConfiguration extends WebMvcConfigurerAdapter {

private static final String[] CLASSPATH_RESOURCE_LOCATIONS = { "classpath:/META-INF/resources/",
        "classpath:/resources/", "classpath:/static/", "classpath:/public/" };

@Override
public void addResourceHandlers(ResourceHandlerRegistry registry) {
    registry.addResourceHandler("/**").addResourceLocations(CLASSPATH_RESOURCE_LOCATIONS);
}

@Override
public void addViewControllers(ViewControllerRegistry registry) {
    registry.addRedirectViewController("/", "/index.html");
}
}

Now accessing localhost:8080/ will redirect to localhost:8080/index.html

Answer 4

In Spring Boot 2.0 you can use this code

@Configuration
public class TomcatInitializer implements 
    WebServerFactoryCustomizer<TomcatServletWebServerFactory> , TomcatContextCustomizer {
    @Override
    public void customize(TomcatServletWebServerFactory factory) {
        factory.addContextCustomizers(this);
    }

    private ErrorPage createStatusErrorPage(int errorCode, String location) {
        ErrorPage errorPage = new ErrorPage();
        errorPage.setErrorCode(errorCode);
        errorPage.setLocation(location);
        return errorPage;
    }

    private ErrorPage createExceptionErrorPage(Class<?> klass, String location) {
        ErrorPage errorPage = new ErrorPage();
        errorPage.setExceptionType(klass);
        errorPage.setLocation(location);
        return errorPage;
    }

    @Override
    public void customize(Context context) {
        context.addWelcomeFile("/index.jsp");
        context.addErrorPage(createStatusErrorPage(404, "/404.jsp"));
        context.addErrorPage(createExeptionErrorPage(Exception.class, "exception.jsp"));
        context.setSessionTimeout(120);
    }
}