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真人性做爰 video网站,seo外包公司多吗,如何进入微网站,做网站怎么赚钱吗目录一、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…

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：