目录
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
java
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
java
@WebServlet("/selectAll")
public class selectAll extends HttpServlet {
private final ProductService productService = new ProductService();
@Override
protected 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);
}
@Override
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
this.doGet(request, response);
}
}之后回到视图层
jsp：
java
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<%--
Created by IntelliJ IDEA.
User: LEGION
Date: 2024/3/13
Time: 13:36
To 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
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：
java
/**
* 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：
java
@WebServlet("/add")
public class Add extends HttpServlet {
@Override
protected 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);
}
@Override
protected 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：
java
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：
java
@WebServlet("/selectById")
public class SelectById extends HttpServlet {
@Override
protected 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);
}
@Override
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
this.doGet(request, response);
}
}显示层：productUpdate.jsp
java
<%@ 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：
java
public void UpdateById(Product product){
final SqlSession sqlSession = sqlSessionFactory.openSession();
final ProductMapper mapper = sqlSession.getMapper(ProductMapper.class);
mapper.updateById(product);
sqlSession.commit();
}servlet：
java
@WebServlet("/updateById")
public class Update extends HttpServlet {
@Override
protected 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);
}
@Override
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
this.doGet(request, response);
}
}测试：
删除：不写了，jsp知道怎么写就行了