MVC模式小教程

xiaoxiao2021-02-28  6

٩(๑>◡<๑)۶今天给大家介绍个新伙伴——MVC模式 一、它是谁?

MVC 模式代表 Model-View-Controller(模型-视图-控制器) 模式。这种模式用于应用程序的分层开发。 Model(模型) - 模型代表一个存取数据的对象或 JAVA POJO。它也可以带有逻辑,在数据变化时更新控制器。 View(视图) - 视图代表模型包含的数据的可视化。 Controller(控制器) - 控制器作用于模型和视图上。它控制数据流向模型对象,并在数据变化时更新视图。它使视图与模型分离开。

二、它在哪? 三、它该怎么办?

package com.News.entity; import java.sql.Date; public class News { private int news_id; private String news_title; private Date news_date; private String author; private String content; private String type; private String discussion; private String picture; private String movie; public int getNews_id() { return news_id; } public void setNews_id(int news_id) { this.news_id = news_id; } public String getNews_title() { return news_title; } public void setNews_title(String news_title) { this.news_title = news_title; } public Date getNews_date() { return news_date; } public void setNews_date(Date news_date) { this.news_date = news_date; } public String getAuthor() { return author; } public void setAuthor(String author) { this.author = author; } public String getContent() { return content; } public void setContent(String content) { this.content = content; } public String getType() { return type; } public void setType(String type) { this.type = type; } public String getDiscussion() { return discussion; } public void setDiscussion(String discussion) { this.discussion = discussion; } public String getPicture() { return picture; } public void setPicture(String picture) { this.picture = picture; } public String getMovie() { return movie; } public void setMovie(String movie) { this.movie = movie; } } <%@ page language="java" import="java.util.*" contentType="text/html; charset=UTF-8"%> <% String path = request.getContextPath(); String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/"; %> <!DOCTYPE html> <html> <head> <meta charset="utf-8"/> <title>登录</title> <link rel="stylesheet" type="text/css" href="css/login.css"> </head> <body> <div id="header"> <div id="header-content"> <div id="header-content2"> <ul> <li><a href="news.html">新闻</a></li> <li><a href="scj.html">收藏夹</a></li> </ul> </div><!--中间结束--> <div id="header-content3"> <a href="login.jsp"?method = 2>登录</a>/ <a href="zc.jsp"method = 1>注册</a>/ <a>用户名</a> </div> </div> </div><!--导航栏结束--> <div id="bbBox"> <div id="bigBox"> <h1>登 录</h1> <form action="UserServlet" method="post"> <span id="s1"></span><p id="p1"><label>用户名:</label><input type="text" name="username" id="userId" placeholder="请输入用户名"/></p> <span id="s2"></span><p id="p2"><label>密码:</label><input type="password" name="password" id="passWord" placeholder="请输入密码" /></p> <input type="submit" value="登录" id="thesubmit"/> <input type="reset" id="res"/> </form> </div> </div> <script type="text/javascript" src="js/login.js"></script> </body> </html> package com.News.controller; import java.io.IOException; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import com.News.dao.UserDao; import com.News.entity.Users; import com.News.service.UserService; public class UserServlet extends HttpServlet { /** * Constructor of the object. */ public UserServlet() { super(); } /** * Destruction of the servlet. <br> */ public void destroy() { super.destroy(); // Just puts "destroy" string in log // Put your code here } /** * The doGet method of the servlet. <br> * * This method is called when a form has its tag value method equals to get. * * @param request the request send by the client to the server * @param response the response send by the server to the client * @throws ServletException if an error occurred * @throws IOException if an error occurred */ public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { doPost(request, response); } /** * The doPost method of the servlet. <br> * * This method is called when a form has its tag value method equals to post. * * @param request the request send by the client to the server * @param response the response send by the server to the client * @throws ServletException if an error occurred * @throws IOException if an error occurred */ public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { request.setCharacterEncoding("UTF-8"); response.setCharacterEncoding("UTF-8"); int method = Integer.parseInt(request.getParameter("method")); switch (method) { case 1: this.register(request, response); break; case 2: this.login(request, response); break; } } public void register(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { String username = request.getParameter("username"); String password = request.getParameter("password"); UserDao uDao = new UserDao(); Users u = new Users(); uDao.Insert(u); } public void login(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { String username = request.getParameter("username"); String password = request.getParameter("password"); String password_true = UserService.Login(username); String mark = UserService.getMark(username); if(!password.equals(password_true)){ System.out.println("Error!"); request.getRequestDispatcher("").forward(request, response); }else{ System.out.println("True!"); if(mark.equals("vip")) request.getRequestDispatcher("").forward(request, response); } } /** * Initialization of the servlet. <br> * * @throws ServletException if an error occurs */ public void init() throws ServletException { // Put your code here } }

四、优秀的它

一个模型提供不同的多个视图表现形式,也能够为一个模型创建新的视图而无须重写模型。模型可复用。维护成本低,扩展性高
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