本文共 3557 字，大约阅读时间需要 11 分钟。

1、 什么是MVC？

MVC全名是Model View Controller，是模型(model)－视图(view)－控制器(controller)的缩写，

注1：不能跨层调用

2、自定义MVC工作原理图

public class Cal {	private String num1;	private String num2;	public String getNum1() {		return num1;	}	public void setNum1(String num1) {		this.num1 = num1;	}	public String getNum2() {		return num2;	}	public void setNum2(String num2) {		this.num2 = num2;	}}

然后写一个主控制器（主控制器：查看是否有对应的子控制器来处理用户请求，如果就调用子控制器来处理请求；没有就报错，就处理不了请求）

public class DispatcherServlet extends HttpServlet {	private static final long serialVersionUID = 6716422786850137569L;	private Map
   
     actionMap = new HashMap<>();		public void init() {		actionMap.put("/addCal", new AddCalAction());		actionMap.put("/delCal", new delCalAction());		actionMap.put("/chengCal", new ChengCalAction());		actionMap.put("/chuCal", new ChuCalAction());	}		@Override	protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {		doPost(req, resp);	}		@Override	protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {		init();		String url = req.getRequestURI();//mvc/xxx.action		url = url.substring(url.lastIndexOf("/"), url.lastIndexOf("."));		Action action = actionMap.get(url);		action.execute(req, resp);	}		}
   

在写一个子控制器（处理用户请求用的）

public interface Action {	void execute(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException ;}

再写一个jsp界面当作计算器

<%@ page language="java" contentType="text/html; charset=UTF-8"    pageEncoding="UTF-8"%>
   	
   
    		num1:
    
    
		num2:
    
    
		
    +		
    -		
    *		
    /	
   

再写一个jsp计算结果

<%@ page language="java" contentType="text/html; charset=UTF-8"    pageEncoding="UTF-8"%>
   结果：${res }

最后再把加减乘除的计算方法写好

加：public class AddCalAction implements Action {	@Override	public void execute(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {		// TODO Auto-generated method stub		String num1 = req.getParameter("num1");		String num2 = req.getParameter("num2");		req.setAttribute("res", Integer.valueOf(num1)+Integer.valueOf(num2));		req.getRequestDispatcher("calRes.jsp").forward(req, resp);			}}	减：public class delCalAction implements Action {	@Override	public void execute(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {		// TODO Auto-generated method stub		String num1 = req.getParameter("num1");		String num2 = req.getParameter("num2");		req.setAttribute("res", Integer.valueOf(num1)-Integer.valueOf(num2));		req.getRequestDispatcher("calRes.jsp").forward(req, resp);			}}	乘：public class ChengCalAction implements Action {	@Override	public void execute(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {		// TODO Auto-generated method stub		String num1 = req.getParameter("num1");		String num2 = req.getParameter("num2");		req.setAttribute("res", Integer.valueOf(num1)*Integer.valueOf(num2));		req.getRequestDispatcher("calRes.jsp").forward(req, resp);			}}	除：public class ChuCalAction implements Action {	@Override	public void execute(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {		// TODO Auto-generated method stub		String num1 = req.getParameter("num1");		String num2 = req.getParameter("num2");		req.setAttribute("res", Integer.valueOf(num1)/Integer.valueOf(num2));		req.getRequestDispatcher("calRes.jsp").forward(req, resp);			}}

结果如下：

转载地址：https://blog.csdn.net/shaobina/article/details/93508607 如侵犯您的版权，请留言回复原文章的地址，我们会给您删除此文章，给您带来不便请您谅解！