SpringMVC框架实现Handler处理器的三种写法

package com.gql.springmvc;
import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.servlet.ModelAndView;
/**
 * 类说明:
 * 处理器的三种写法
 * @guoqianliang1998.
 */
@Controller
public class UserController {
 //1.SpringMVC开发方式
 @RequestMapping("/hello")
 public ModelAndView hello(){
 ModelAndView mv = new ModelAndView();
 mv.addObject("msg","hello world!");
 mv.setViewName("index.jsp");
 return mv;
 }
 
 //2.原生Servlet开发方式
 @RequestMapping("xx")
 public void xx(HttpServletRequest request,HttpServletResponse response) throws ServletException, IOException{
 request.setAttribute("msg", "周冬雨");
 request.getRequestDispatcher("/index.jsp").forward(request, response);
 }
 
 //3.开发中常用
 @RequestMapping("yy")
 public String yy(Model model){
 model.addAttribute("msg", "双笙");
 return "forward:/index.jsp";//forward写不写都是转发,redirect代表重定向.
 }
}

 @RequestMapping("/hello")
 public ModelAndView hello(){
 ModelAndView mv = new ModelAndView();
 mv.addObject("msg","hello world!");
 mv.setViewName("index.jsp");
 return mv;
 }

 @RequestMapping("xx")
 public void xx(HttpServletRequest request,HttpServletResponse response) throws ServletException, IOException{
 request.setAttribute("msg", "周冬雨");
 request.getRequestDispatcher("/index.jsp").forward(request, response);
 }
 

 @RequestMapping("yy")
 public String yy(Model model){
 model.addAttribute("msg", "双笙");
 return "forward:/index.jsp";
 }