@Controller //这个注解会告知<context:component:scan> 将HomeController自动检测为一个Bean
@RequestMapping("/home")  //这是根Url
public class HomeController {
    
    private UserService userService;
    
    @Autowired
    public HomeController(UserService userService){
        this.userService = userService;
    }
    
    //指定请求的路径,处理get请求的路径为 xxx/home/home.html的请求
    @RequestMapping(value="home.html",method=RequestMethod.GET)
    public String showHomePage(@RequestParam("name")String username,Model model){
        model.addAttribute("username",username);
        model.addAttribute("count", userService.getUsersCount());
        return "home";
    }
}