configuring Spring MVC welcome page - spring

Question

I was trying for two days to set up the index page using spring 4.
After many attempts I got a piece of code that worked
But I did not understand why it worked.
Could you tell me why.
public class MyWebApplicationInitializer
extends AbstractAnnotationConfigDispatcherServletInitializer
{
protected Class<?>[] getRootConfigClasses() {
return new Class[] {AplicationConfig.class};
}
protected Class<?>[] getServletConfigClasses() {
return new Class[] {WebConfiguration .class};
}
protected String[] getServletMappings() {
return new String[] {"/"};
}
}
Here's the snippet of code I found
// #Bean
// public InternalResourceViewResolver internalResourceViewResolver() {
// InternalResourceViewResolver viewResolver = new InternalResourceViewResolver();
// viewResolver.setPrefix("/WEB-INF/html/");
// viewResolver.setSuffix(".html");
// return viewResolver;
// }
#Override
public void addResourceHandlers(ResourceHandlerRegistry registry) {
registry.addResourceHandler("/*.html").addResourceLocations("/WEB-INF/html/");
super.addResourceHandlers(registry);
}
#Override
public void addViewControllers(ViewControllerRegistry registry) {
registry.addViewController( "/" ).setViewName( "forward:/index.html" );
// registry.setOrder( Ordered.HIGHEST_PRECEDENCE );
// super.addViewControllers( registry );
}
my folders
1) why InternalResourceViewResolver do not work?
2) How does addResourceHandler and addViewController work? What are these paths?
3)And how do I add the css and javascripts file to the index page? like
<link href="/css/bootstrap.min.css" rel="stylesheet">
The page loads but this without the css and javascript files
I want to thank everyone who helped me because I'm a newbie in spring, thanks guys.

Answer 1

Only configuring InternalResourceViewResolver is not enough to serve static html. You also need to bind a path through controller to serve the page. As this is just a static page you can do that with
addViewControllers.
registry.addViewController("/").setViewName("index");
2.
addResourceHandlers: Add handlers to serve static resources such as images, js, and, css files from specific locations under web application root, the classpath, and others.
addViewControllers: Configure simple automated controllers pre-configured with the response status code and/or a view to render the response body. This is useful in cases where there is no need for custom controller logic -- e.g. render a home page, perform simple site URL redirects, return a 404 status with HTML content, a 204 with no content, and more.
http://docs.spring.io/spring/docs/current/javadoc-api/org/springframework/web/servlet/config/annotation/WebMvcConfigurer.html#addResourceHandlers-org.springframework.web.servlet.config.annotation.ResourceHandlerRegistry-
3.
To make the resources(js, css, img) available, you need to add following configuration inside your addResourceHandlers methods.
registry.addResourceHandler("/css/**").addResourceLocations("/css/");
registry.addResourceHandler("/js/**").addResourceLocations("/js/");
registry.addResourceHandler("/img/**").addResourceLocations("/img/");
And then to include css or js in a JSP page, you can use JSTL tag c:url or Spring tag spring:url.
<link href="<c:url value="/css/styles.css" />" rel="stylesheet">
<spring:url value="/css/styles.css" var="mainCss" />
<link href="${mainCss}" rel="stylesheet" />