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JavaWeb06-MVC和三层架构

news 2025/9/11 12:55:39

一、MVC模式

1.概述

2.好处

二、三层架构

1.概述

三、MVC与三层架构

四、练习

一、MVC模式

1.概述

MVC是一种分层开发的模式，其中

M：Model，业务模型，处理业务 V： View，视图，界面展示 C：Controller，控制器，处理请求，调用型和视图

2.好处

职责单一，互不影响
有利于分工协作
有利于组件重用

二、三层架构

1.概述

View视图不只是JSP！

数据访问层（持久层）:对数据库的CRUD基本操作

一般命名为反转公司网址/controller

业务逻辑层（业务层）:对业务逻辑进行封装，组合数据访问层层中基本功能，形成复杂的业务逻辑功能。

一般命名为反转公司网址/service

表现层:接收请求，封装数据，调用业务逻辑层，响应数据

一般命名为反转公司网址/dao或者mapper

三、MVC与三层架构

四、练习

给上次的数据添加一个状态字段，0禁用，1启用，2预售，设个默认值1即可

使用三层架构思想开发

参考下图：

java目录结构

代码，只写主要的了

service包下

public class ProductService {final SqlSessionFactory sqlSessionFactory = SqlSessionFactoryUtils.getSqlSessionFactory();public List<Product> selectAll(){final SqlSession sqlSession = sqlSessionFactory.openSession();final ProductMapper mapper = sqlSession.getMapper(ProductMapper.class);final List<Product> products = mapper.selectAll();sqlSession.close();return products;};
}

web包下

@WebServlet("/selectAll")
public class selectAll extends HttpServlet {private final ProductService productService = new ProductService();@Overrideprotected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
final List<Product> products = productService.selectAll();request.setAttribute("product",products);request.getRequestDispatcher("/jsp/product.jsp").forward(request,response);}
@Overrideprotected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {this.doGet(request, response);}
}

之后回到视图层

jsp：

<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<%--Created by IntelliJ IDEA.User: LEGIONDate: 2024/3/13Time: 13:36To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<%@ page isELIgnored="false" %>
<%--<% final Object product = request.getAttribute("product");%>--%>
<html>
<head><title>Title</title>
</head>
<body><h1>product列表</h1><table border="1px solid black"><tr><th>商品序号</th><th>商品id</th><th>商品名</th><th>商品图片</th><th>商品价格</th><th>商品评论数</th><th>商品分类</th><th>商品状态</th><th>商品发布时间</th><th>商品更新时间</th></tr><c:forEach items="${product}" var="product" varStatus="status"><tr><%--                index从0开始，count从1开始--%><td>${status.count}</td><%--                ${user.id} => Id => getId()--%><td>${product.id}</td><td>${product.title}</td><td><img src="${product.imgUrl}" alt="" width="75px" height="75px"></td><td>${product.price}</td><td>${product.comment}</td><td>${product.category}</td><td>${product.status}</td><td>${product.gmtCreate}</td><td>${product.gmtModified}</td></tr></c:forEach>
</table>
</body>
</html>

预览图：

添加：

html

<form action="/product_demo_war/add" method="post"><input type="text" name="title" placeholder="商品名称"><br><input type="text" name="price" placeholder="商品价格"><br>
<!--        图片上传在这里就先不写了--><input type="number" name="category" placeholder="商品类型（数字就好）"><br><input type="radio" name="status">启用<input type="radio" name="status">禁用<br><input type="submit" value="添加"></form>

service：

/*** 添加商品* @param product 商品对象*/
public void add(Product product){final SqlSession sqlSession = sqlSessionFactory.openSession();final ProductMapper mapper = sqlSession.getMapper(ProductMapper.class);mapper.add(product);sqlSession.commit();sqlSession.close();
}

web：

@WebServlet("/add")
public class Add extends HttpServlet {@Overrideprotected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {ProductService productService = new ProductService();final String title = request.getParameter("title");final String price = request.getParameter("price");final Integer status = Integer.parseInt(request.getParameter("status"));final Integer category = Integer.parseInt(request.getParameter("category"));Product product = new Product(title,price,category,status);productService.add(product);request.getRequestDispatcher("/selectAll").forward(request,response);}
@Overrideprotected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {this.doGet(request, response);}
}

预览：

修改：

有两步：

显示原先的数据：回显

修改现有的数据：修改

第一部分回显：根据id显示值

service：

public Product selectById(Long id){final SqlSession sqlSession = sqlSessionFactory.openSession();final ProductMapper mapper = sqlSession.getMapper(ProductMapper.class);final Product product = mapper.selectById(id);sqlSession.close();return product;
}

web：

@WebServlet("/selectById")
public class SelectById extends HttpServlet {@Overrideprotected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {final String id = request.getParameter("id");ProductService productService = new ProductService();final Product product = productService.selectById(Long.parseLong(id));request.setAttribute("product",product);System.out.println(id);request.getRequestDispatcher("/jsp/productUpdate.jsp").forward(request,response);}
@Overrideprotected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {this.doGet(request, response);}
}

显示层：productUpdate.jsp

<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<%@ page isELIgnored="false" %>
<html>
<head><title>修改</title><style>.text {width: 100%;}</style>
</head>
<body>
<form action="/product_demo_war/updateById" method="post"><input type="hidden" name="id" value="${product.id}"><input class="text" type="text" name="title" placeholder="商品名称" value="${product.title}"><br><input class="text" type="text" name="price" placeholder="商品价格" value="${product.price}"><br><!--        图片上传在这里就先不写了--><input class="text" type="number" name="category" placeholder="商品类型（数字就好）" value="${product.category}"><br><c:if test="${product.status == 1}"><input type="radio" name="status" value="1" checked>启用<input type="radio" name="status" value="0">禁用</c:if><c:if test="${product.status == 0}"><input type="radio" name="status" value="1">启用<input type="radio" name="status" value="0" checked>禁用</c:if>
<br><input type="submit" value="修改">
</form>
</body>
</html>

第二部分修改：

service：

public void UpdateById(Product product){final SqlSession sqlSession = sqlSessionFactory.openSession();final ProductMapper mapper = sqlSession.getMapper(ProductMapper.class);mapper.updateById(product);sqlSession.commit();
}

servlet：

@WebServlet("/updateById")
public class Update extends HttpServlet {@Overrideprotected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
final Long id = Long.parseLong(request.getParameter("id"));final String title = request.getParameter("title");final String price = request.getParameter("price");final Integer category = Integer.parseInt(request.getParameter("category"));final Integer status = Integer.parseInt(request.getParameter("status"));Date gmtModified = new Date();
Product product = new Product(id,title,price,category,status,gmtModified);ProductService productService = new ProductService();productService.UpdateById(product);
request.getRequestDispatcher("/selectAll").forward(request,response);
}
@Overrideprotected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {this.doGet(request, response);}
}

测试：