SpringMVC框架|Handler处理器的三种写法

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一、SpringMVC中的处理器

配置完SpringMVC的处理器映射器，处理适配器，视图解析器后，需要手动写处理器。关于处理器的写法有三种，无论怎么写，执行流程都是①处理映射器通过@Controller注解找到处理器，继而②通过@RequestMapping注解找到用户输入的url。下面分别介绍这三种方式。

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.
	}
}

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.Servlet原生开发方式

	@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.开发中常用的方式

在return的字符串中，forward写不写都是代表转发，redirect则代表重定向。

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