SpringMVC Controller doesn't work

I am learning SpringMVC and try to build a HelloWorld webapp.
I build this project with eclipse using the code from Sping in Action 4th Edition,
but when I test it on my browser by visiting http://localhost:8080/homepage
I got 404 error.


And the most weired thing is, if I test the controller using MockMvc (method provided by Spring in Action, it will pass the test.
SO I am wondering where did I do wrong?

The structure of my project:

SpittrWebAppInitializer.java:

package spittr.config;

import org.springframework.web.servlet.support.AbstractAnnotationConfigDispatcherServletInitializer;

public class SpittrWebAppInitializer extends AbstractAnnotationConfigDispatcherServletInitializer {

    @Override
    protected Class<?>[] getRootConfigClasses() {
        // TODO Auto-generated method stub
        return new Class<?>[] {RootConfig.class};
    }

    @Override
    protected Class<?>[] getServletConfigClasses() {
        // TODO Auto-generated method stub
        return new Class<?>[] {WebConfig.class};
    }

    @Override
    protected String[] getServletMappings() {
        // TODO Auto-generated method stub
        return new String[]{"/"};
    }

}

WebConfig.java

package spittr.config;

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.WebMvcConfigurerAdapter;
import org.springframework.web.servlet.view.InternalResourceViewResolver;

@Configuration
@EnableWebMvc
@ComponentScan("spitter.web")
public class WebConfig extends WebMvcConfigurerAdapter {

    @Bean
    public ViewResolver viewRseolver(){
        InternalResourceViewResolver resolver = new InternalResourceViewResolver();
        resolver.setPrefix("/WEB-INF/views/");
        resolver.setSuffix(".jsp");
        resolver.setExposeContextBeansAsAttributes(true);
        return resolver;
    }

    @Override
    public void configureDefaultServletHandling(DefaultServletHandlerConfigurer configurer){
        configurer.enable();
    }

}

RootConfig.java

package spittr.config;

import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.ComponentScan.Filter;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.FilterType;
import org.springframework.web.servlet.config.annotation.EnableWebMvc;

@Configuration
@ComponentScan(basePackages={"spitter"},excludeFilters={@Filter(type=FilterType.ANNOTATION,value=EnableWebMvc.class)})
public class RootConfig {

}

HomeController.java

package spittr.web;

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

@Controller
@RequestMapping({"/","/homepage"})
public class HomeController {

    @RequestMapping(method=RequestMethod.GET)
    public String home(){
        return "home";
    }

}