controller層中，參數的獲取方式以及作用域的問題

package com.krry.web;

import javax.servlet.http.HttpServletRequest;

import org.springframework.stereotype.Controller;
import org.springframework.ui.ModelMap;
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.servlet.ModelAndView;

import com.fasterxml.jackson.annotation.JsonTypeInfo.Id;

import bean.User;


@Controller
@RequestMapping("/model")
public class ModelMapController extends BaseController {
    /********參數獲取的方式**************************/

    //http://localhost/krryxa/model/hanlder/1.html
    @RequestMapping("/handler/{id}")
    public String handler(@PathVariable("id")Integer id){
    //獲得參數id為1
        return "redirect:/success.jsp";
    }
    
    //http://localhost/krryxa/model/handler2.html?id=5
    @RequestMapping("/handler2")
    public String handler2(Integer id){
    //獲得參數id為5
        System.out.println(id);
        return "redirect:/success.jsp";
    }
    
    //通過對象的的注入方式最好
    //http://localhost/krryxa/model/handler3.html?username=1351
    @RequestMapping("/handler3")
    public String handler3(User user){
    //獲得參數username為1351
        System.out.println(user.getUsername());
        return "redirect:/success.jsp";
    }
    
    //http://localhost/krryxa/model/handler4.html?id=5
    @RequestMapping("/handler4")
    public String handler4(@ModelAttribute("teacher")User user){//若sessiong域中teacher改變了，這里也會改變
    //獲得參數id為5
        System.out.println(request.getParameter("id"));
        return "redirect:/success.jsp";
    }
    
    

    /**作用域的問題reuqest session application 以下作用域的范圍都是:request**/

    //在index頁面直接用${message}獲取
    @RequestMapping("/handler7")
    public String handler7(ModelMap map){
        //這里是map的addAttribute設置
        map.addAttribute("message", "我愛你嗎。你們愛我我嗎");
        return "model/index";
    }
    
    //在index頁面直接用${message}獲取
    @RequestMapping("/handler5")
    public String handler5(){
        request.setAttribute("message", "我愛你嗎。你們愛我我嗎");
        return "model/index";
    }
    
    //在index頁面直接用${message}獲取
    @RequestMapping("/handler6")
    public ModelAndView handler6(){
        //視圖和作用域融合體
        ModelAndView modelAndView = new ModelAndView();
        modelAndView.setViewName("model/index"); //跳轉到這個頁面
        modelAndView.addObject("message", "是打發是大法師的發送到發士大夫阿什頓");
        return modelAndView;
    }
    //在index頁面直接用${user.username}獲取
    @RequestMapping("/handler8")
    public String handler8(@ModelAttribute("user")User user){
        user.setUsername("ModelAttribute 我愛你嗎。你們愛我嗎");
        return "model/index";
    }
    
    
}