MVC模式小教程
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2024-02-26 18:53:16
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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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