Pragmatically Spring MVC example without using XML (Pure java based configuration)

After we have the Servlet 3 version, we have the option to ignore the web.xml file in our java based web application. Similarly, Spring gives us the option to ignore its XML based configuration in new releases. So, you can create the Spring MVC application without having any xml file in it. See the Example.

Here the java code to create the Web application initializer. Implementation of WebApplicationInitializer interface gives the provision to provide the configuration that would have in web.xml file

package myweb.app;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.ServletRegistration;

import org.springframework.web.WebApplicationInitializer;
import org.springframework.web.context.support.AnnotationConfigWebApplicationContext;
import org.springframework.web.servlet.DispatcherServlet;


public class WebAppInitializer implements WebApplicationInitializer {

	@Override
	public void onStartup(ServletContext servletContext) throws ServletException {
		AnnotationConfigWebApplicationContext ctx = new AnnotationConfigWebApplicationContext();
		ctx.setServletContext(servletContext);
		ctx.register(DispatcherConfig.class);
		ServletRegistration.Dynamic servlet = servletContext.addServlet("dispatcher", new DispatcherServlet(ctx));
		servlet.setLoadOnStartup(1);
		servlet.addMapping("/");
	}

}

Now here, dispatcher configuration is created which would be used by DispatcherServlet.

package myweb.app;

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.ViewResolver;
import org.springframework.web.servlet.config.annotation.DefaultServletHandlerConfigurer;
import org.springframework.web.servlet.config.annotation.EnableWebMvc;
import org.springframework.web.servlet.config.annotation.ResourceHandlerRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurerAdapter;
import org.springframework.web.servlet.view.InternalResourceViewResolver;
import org.springframework.web.servlet.view.JstlView;

@Configuration
@EnableWebMvc
@ComponentScan(basePackages = "myweb")
public class DispatcherConfig extends WebMvcConfigurerAdapter {
	@Bean
	public ViewResolver viewResolver() {
		InternalResourceViewResolver viewResolver = new InternalResourceViewResolver();
		viewResolver.setViewClass(JstlView.class);
		viewResolver.setPrefix("/WEB-INF/views/");
		viewResolver.setSuffix(".jsp");
		return viewResolver;
	}
	
	
	@Override
    public void addResourceHandlers(ResourceHandlerRegistry registry) {
        registry.addResourceHandler("/resources/**").addResourceLocations("/resources/");
    }
	
	
	@Override
	public void configureDefaultServletHandling(DefaultServletHandlerConfigurer configurer) {
		configurer.enable();
	}

}

Here is the controller code that will be as it is as it was in xml based configuration project.

package myweb.app;

import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;

@Controller
public class WelcomeController {
	@RequestMapping("/")
	public @ResponseBody String welcome() {
		return "Welcome to Spring MVC. This is example without using xml based configurations";
	}
}