一.什么是MVC设计模式？
1.2 MVC设计模式有什么优点？
①降低代码耦合性：在MVC模式中，三个层各司其职，所有如果一旦哪一层的需求发生了变化，就只需要更改相应层的代码而不会影响到其他层的代码
②有利于分工合作：在MVC模式中，由于按层把系统分开，那么就能更好的实现开发中的分工，网页设计人员可进行开发视图层中的JSP，而对业务熟悉的人员可开发业务层，而其他开发人员可开发控制层
③有利于组件的重用：如控制层可独立成一个能用的组件，表示层也可做成通用的操作界面，可以为一个模式在运行时同时建立和使用多个视图
二.MVC运用（家居商城）
2.1 实现登录
package com.zking.servlet; import java.io.IOException; import java.io.PrintWriter; import javax.servlet.ServletException; import javax.servlet.annotation.WebServlet; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import javax.servlet.http.HttpSession; import com.zking.biz.IUserBiz; import com.zking.biz.UserBiz; import com.zking.entity.User; /** * 登录业务处理 控制器 * @author PC * */ @WebServlet("/login.do") public class LoginServlet extends HttpServlet { @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 { //设置编码 req.setCharacterEncoding("utf-8"); resp.setContentType("text/html; charset=UTF-8"); //拿session和out HttpSession session = req.getSession(); PrintWriter out = resp.getWriter(); //接收表单提交过来的值 用户名 密码 String uname=req.getParameter("uname"); String upwd=req.getParameter("upwd"); //servlet调用biz IUserBiz iub = new UserBiz(); //调用登录方法 User u = iub.login(uname, upwd); //判断 if(u!=null) { //存起来session session.setAttribute("user", u);//键 值 //跳转到主界面 index.do加载数据 resp.sendRedirect("index.do?index=1");//为了让首页选中 } else { out.print("<scrpit>alert('用户名或者密码有误')；location.href='login.jsp';</scrpit>"); } } }
2.2 绑定轮播【随机三个商品】
2.2.1 效果预览
index.jsp
<!--轮播效果 --> <div class="container"> <div id="carouselExampleCaptions" class="carousel slide" data-ride="carousel"> <ol class="carousel-indicators"> <li data-target="#carouselExampleCaptions" data-slide-to="0" class="active"></li> <li data-target="#carouselExampleCaptions" data-slide-to="1"></li> <li data-target="#carouselExampleCaptions" data-slide-to="2"></li> </ol> <div class="carousel-inner"> <c:forEach items="${lbls}" var="g" varStatus="vs"> <div class="carousel-item ${vs.index==0?'active':''}"> <img src="${g.gpath}" width="100%" height="500px" alt="..."> <div class="carousel-caption d-none d-md-block"> <h5>${g.gname}</h5> <p>${g.ginfo}</p> </div> </div> </c:forEach>
2.3 绑定最新上架&热门家居
2.3.1 效果预览
2.3.2 代码实现
数据库脚本
--类别表 create table tb_type ( tid NUMBER,--类别id tname VARCHAR2(20) --类别名称 ) --插入数据 insert into tb_type (tid, tname) values (1, '布艺软饰'); insert into tb_type (tid, tname) values (2, '装饰摆件'); insert into tb_type (tid, tname) values (3, '蜡艺香薰'); insert into tb_type (tid, tname) values (4, '墙饰壁挂'); insert into tb_type (tid, tname) values (5, '创意家居'); commit; --商品表 tb_goods --插入数据 insert into tb_goods (gid, gname, tid, gprice, gxl, gtime, gpath, ginfo) values (1, '商品3', 3, 45.4, 38, '2023-01-01', 'img/bz02.jpg', '不畏将来，不念过往'); insert into tb_goods (gid, gname, tid, gprice, gxl, gtime, gpath, ginfo) values (2, '商品2', 4, 29.9, 8, '2022-10-23', 'img/bz04.jpg', '夏天有着迟暮的霞光,正如晚来的你,皆是笑意'); insert into tb_goods (gid, gname, tid, gprice, gxl, gtime, gpath, ginfo) values (3, '毛茸茸的小物件', 5, 12.9, 104, '2018-02-04', 'img/bz05.jpg', '世界的温柔，是晚来的善意和干净的你'); insert into tb_goods (gid, gname, tid, gprice, gxl, gtime, gpath, ginfo) values (4, '可爱舒适的抱枕', 2, 38.8, 91, '2023-13-09', 'img/bz03.jpg', '人间骄阳正好，风过林梢，彼时还正当年少'); insert into tb_goods (gid, gname, tid, gprice, gxl, gtime, gpath, ginfo) values (5, '商品12', 2, 18.8, 45, '2022-01-23', 'img/bz12.jpg', '踏月而来，这繁星便是赠礼'); insert into tb_goods (gid, gname, tid, gprice, gxl, gtime, gpath, ginfo) values (6, '商品1', 2, 23.9, 145, '2021-02-23', 'img/bz06.jpg', '你被黑暗敲打恰恰说明你是光明本身'); insert into tb_goods (gid, gname, tid, gprice, gxl, gtime, gpath, ginfo) values (7, '商品666', 1, 89.9, 888, '2020-11-22', 'img/bz11.jpg', '回首亘年漫月里所有怦然心动，你仍拨得头筹'); insert into tb_goods (gid, gname, tid, gprice, gxl, gtime, gpath, ginfo) values (8, '好看的花呀', 3, 9.9, 666, '2019-02-20', 'img/bz10.jpg', '最美是牵着你的手一路狂奔'); insert into tb_goods (gid, gname, tid, gprice, gxl, gtime, gpath, ginfo) values (9, '北欧家具', 1, 4.5, 10, '2022-12-24', 'img/bz08.jpg', '生活很暗，抱歉，我也没光'); insert into tb_goods (gid, gname, tid, gprice, gxl, gtime, gpath, ginfo) values (10, '商品13', 4, 9.9, 100, '2020-12-20', 'img/bz09.jpg', '清水煮岁月，不悲不喜'); commit;
<!-- 最新上架①或②--> <!-- 微章方式 ①--> <!-- <div class="h2 " style="margin-top: 10px;"> <span class="badge badge-danger ">最新上架</span> </div> --> <!-- 背景图片方式② --> <div class="bq"> 最新上架 </div> <div class="row"> <c:forEach items="${zxls}" var="g"> <div class="col"> <!-- 画像 text-center"居中--> <figure class="figure text-center"> <!--<a href="xq.do?gid=${g.gid}"> 详情页面 自己写 --> <a href="xq.do?gid=${g.gid}"> <img src="${g.gpath}" class="figure-img img-fluid rounded" alt="..."></a> <figcaption class="figure-caption"><b>${g.gname}</b> <b>¥${g.gprice}</b></figcaption> </figure> </div> </c:forEach> </div> <!-- 热门家居 --> <div class="bq"> 热门家居 </div> <div class="row"> <c:forEach items="${xlls}" var="g"> <div class="col"> <!-- 画像 text-center"居中--> <figure class="figure text-center"> <!--<a href="xq.do?gid=${g.gid}"> 详情页面 自己写 --> <a href="xq.do?gid=${g.gid}"> <img src="${g.gpath}" class="figure-img img-fluid rounded" alt="..."></a> <figcaption class="figure-caption"><b>${g.gname}</b> <b>¥${g.gprice}</b></figcaption> </figure> </div> </c:forEach> </div>
2.4 页面包含
2.4.1 语法
<!--页面包含 -->
<jsp:include page="header.jsp"></jsp:include>
<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%> <%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%> <!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <meta http-equiv="X-UA-Compatible" content="IE=edge"> <meta name="viewport" content="width=device-width, initial-scale=1.0"> <title>案例1：首页最新上架&热门家居实现</title> <!-- 支持手机端 --> <meta name="viewport" content="width=device-width,initial-scale=1.0"> <!-- 引入CSS --> <link rel="stylesheet" href="CSS/bootstrap.css" /> <style> .navbar-collapse { /*1代表弹性扩大占用父容器剩余部分 0代表不占用*/ flex-grow: 0; } .active { font-weight: bold; /*加粗*/ } </style> </head> <body> <!-- 导航条 --> <nav class="navbar navbar-expand-lg navbar-light bg-light"> <!-- 固定容器 --> <div class="container"> <a class="navbar-brand" href="#">你好<b>${user.uname}</b>,欢迎来到集美家居</a> <button class="navbar-toggler" type="button" data-toggle="collapse" data-target="#navbarNav" aria-controls="navbarNav" aria-expanded="false" aria-label="Toggle navigation"> <span class="navbar-toggler-icon"></span> </button> <div class="collapse navbar-collapse" id="navbarNav"> <ul class="navbar-nav"> <!-- active激活的 --> <li class="nav-item ${param.index==1?'active':''}"> <a class="nav-link" href="index.do?index=1">首页<span class="sr-only">(current)</span></a> </li> <li class="nav-item ${param.index==2?'active':''}"> <a class="nav-link" href="type.jsp?index=2">分类</a> </li> <c:if test="${empty user}"><!--没登录 --> <li class="nav-item"> <a class="nav-link" href="login.jsp">登录</a> </li> <li class="nav-item"> <a class="nav-link ">注册</a> </li> </c:if> <c:if test="${not empty user}"><!--登录 --> <li class="nav-item"> <a class="nav-link" href="exit.do">退出</a> </li> </c:if> <li class="nav-item ${param.index==5?'active':''}"> <a class="nav-link" href="cart.jsp?index=5">我的购物车</a> </li> </ul> </div> </div> </nav> <!-- 引入jQuery的类库 --> <!-- 再引入Bootstrap的类库 --> <script src="js/jquery-3.6.4.js"></script> <script src="js/bootstrap.js"></script> </body> </html>
2.4.2 处理
注意：${param.key} 相当于request.getParameter("key")用于jsp页面取值
<ul class="navbar-nav"> <!-- active激活的 --> <li class="nav-item ${param.index==1?'active':''}"> <a class="nav-link" href="index.do?index=1">首页<span class="sr-only">(current)</span></a> </li> <li class="nav-item ${param.index==2?'active':''}"> <a class="nav-link" href="type.jsp?index=2">分类</a> </li> </ul> //登录成功后 跳转到主界面的加载数据处 让首页默认选中 resp.sendRedirect("indedx.do?index=1")
2.5 登录与否判断
--登录了则导航条上出现登录名并不显示登录，而显示退出
<c:if test="${not empty user}"><!--登录 --> <li class="nav-item"> <a class="nav-link" href="exit.do">退出</a> </li> </c:if> req.setCharacterEncoding("utf-8"); HttpSession session = req.getSession(); session.setAttribute("user", null); resp.sendRedirect("login.jsp"); --没有登录才显示登录，注册选项 <c:if test="${empty user}"><!--没登录 --> <li class="nav-item"> <a class="nav-link" href="login.jsp">登录</a> </li> <li class="nav-item"> <a class="nav-link " href="register.jsp">注册</a> </li> </c:if>
