Spring MVC - @ModelAttribute Examples

import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.ModelAttribute;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import java.time.LocalDateTime;
import java.util.concurrent.atomic.AtomicLong;
import java.util.logging.Logger;

@Controller
@RequestMapping("users")
public class UserController {
    private static final Logger LOGGER =
            Logger.getLogger(UserController.class.getName());

    private static AtomicLong counter = new AtomicLong();

    @RequestMapping
    public String handleRequest(Model model) {
        model.addAttribute("msg", "user request received");
        LOGGER.info(model.toString());
        return "my-page";
    }

    @RequestMapping("{id}")
    public String handleRequestById(@PathVariable("id") String id,
                                    Model model) {
        model.addAttribute("msg", "user request received for the id : " + id);
        LOGGER.info(model.toString());
        return "my-page";
    }

    @ModelAttribute("time")
    public LocalDateTime getRequestTime() {
        return LocalDateTime.now();
    }

    @ModelAttribute("visits")
    public long getRequestCount() {
        return counter.incrementAndGet();
    }

    @ModelAttribute("querier")
    public void populateIds(@RequestParam(value = "querier", required = false)
                            String querier,
                            Model model) {
        model.addAttribute("querier", querier == null ? "guest" : querier);
    }
}

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.ModelAttribute;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;

@Controller
@RequestMapping("users")
public class UserController {
    @Autowired
    private UserService userService;

    @RequestMapping("{userId}")
    public String handleRequestById(@ModelAttribute("user") User user,
                                    Model model) {
        model.addAttribute("msg", "user by id: " +user);
        return user != null && "admin".equals(user.getRole()) ?
                "admin-page" : "user-page";
    }

    @ModelAttribute("user")
    public User getUser(@PathVariable("userId") long userId) {
        return userService.getUserById(userId);
    }
}

    @ModelAttribute("visitor")
    public Visitor getVisitor(HttpServletRequest request) {
        return new Visitor(request.getRemoteAddr());
    }
}