案例-基于MVC和三层架构实现商品表的增删改查

0. 项目介绍

其他项目-用户登录注册页面：https://blog.csdn.net/meini32/article/details/132305323

项目介绍
需求：完成品牌数据的增删改查操作

技术框架说明

三层架构是将我们的项目分成了三个层面，分别是 表现层 、 业务逻辑层 、 数据访问层。
整个流程是，浏览器发送请求，表现层的Servlet接收请求并调用业务逻辑层的方法进行业务逻辑处理，而业务逻辑层方法调用数据访问层方法进行数据的操作，依次返回到serlvet，然后servlet将数据交由 JSP 进行展示。

• 数据访问层：Mybatis、mysql
• 业务逻辑层：JAVA
• 表现层：JSP、Servlet

实现步骤

1. 环境准备

环境准备

• 1. 创建新的项目 brand_demo，引入坐标配置pom文件（）
• 2. 创建三层架构的包结构
• 3. 数据库表 tb_brand
• 4. 实体类 Brand

• 5. MyBatis 基础环境配置

     • Mybatis-config.xml

     • BrandMapper.xml

     • BrandMapper接口

Mybatis-config.xml

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE configurationPUBLIC "-//mybatis.org//DTD Config 3.0//EN""http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration><!--起别名--><typeAliases><package name="com.itheima.pojo"/></typeAliases><environments default="development"><environment id="development"><transactionManager type="JDBC"/><dataSource type="POOLED"><property name="driver" value="com.mysql.jdbc.Driver"/><property name="url" value="jdbc:mysql:///db1?useSSL=false&amp;useServerPrepStmts=true"/><property name="username" value="root"/><property name="password" value="123456"/></dataSource></environment></environments><mappers><!--扫描mapper--><package name="com.itheima.mapper"/></mappers>
</configuration>

pom.xml文件配置

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"><modelVersion>4.0.0</modelVersion><groupId>org.example</groupId><artifactId>brand-demo</artifactId><version>1.0-SNAPSHOT</version><packaging>war</packaging><properties><maven.compiler.source>8</maven.compiler.source><maven.compiler.target>8</maven.compiler.target></properties><dependencies><!-- mybatis --><dependency><groupId>org.mybatis</groupId><artifactId>mybatis</artifactId><version>3.5.5</version></dependency><!--mysql--><dependency><groupId>mysql</groupId><artifactId>mysql-connector-java</artifactId><version>5.1.34</version></dependency><!--servlet--><dependency><groupId>javax.servlet</groupId><artifactId>javax.servlet-api</artifactId><version>3.1.0</version><scope>provided</scope></dependency><!--jsp--><dependency><groupId>javax.servlet.jsp</groupId><artifactId>jsp-api</artifactId><version>2.2</version><scope>provided</scope></dependency><!--jstl--><dependency><groupId>jstl</groupId><artifactId>jstl</artifactId><version>1.2</version></dependency><dependency><groupId>taglibs</groupId><artifactId>standard</artifactId><version>1.1.2</version></dependency></dependencies><build><plugins><plugin><groupId>org.apache.tomcat.maven</groupId><artifactId>tomcat7-maven-plugin</artifactId><version>2.2</version></plugin></plugins></build></project>

工具类 SqlsessionFactoryUtils

package com.itheima.util;import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;import java.io.IOException;
import java.io.InputStream;public class SqlSessionFactoryUtils {private static SqlSessionFactory sqlSessionFactory;static{InputStream inputStream = null;try {inputStream = Resources.getResourceAsStream("mybatis-config.xml");} catch (IOException e) {e.printStackTrace();}SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);}public static SqlSessionFactory getSqlSessionFactory(){return sqlSessionFactory;}
}

属性名称对应不上解决方法

在BrandMapper映射文件里，定义映射关系

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapperPUBLIC "-//mybatis.org//DTD Mapper 3.0//EN""http://mybatis.org/dtd/mybatis-3-mapper.dtd"><!--
namespace:名称空间
--><mapper namespace="com.itheima.mapper.BrandMapper"><!--    resultMap 标签定义映射关系--><resultMap id="brandRseultMap" type="brand"><result column="brand_name" property="brandName"></result><result column="company_name" property="companyName"></result></resultMap></mapper>

在接口方法中指定该映射

public interface BrandMapper {//查看所有@ResultMap("brandResultMap")@Select("select * from tb_brand;")List<Brand> selectAll();
}

2. 查看所有

说明：当我们点击 index.html 页面中的 查询所有 这个超链接时，就能查询到上图右半部分的数据。

2.1 编写BrandMapper接口

public interface BrandMapper {//查看所有@Select("select * from tb_brand;")List<Brand> selectAll();
}

2.2 编写服务类，创建BrandService，用于调用该方法

package com.itheima.service;import com.itheima.mapper.BrandMapper;
import com.itheima.pojo.Brand;
import com.itheima.util.SqlSessionFactoryUtils;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;import java.util.List;public class BrandService {SqlSessionFactory sqlSessionFactory =SqlSessionFactoryUtils.getSqlSessionFactory();//查所有public List<Brand> selectAll(){//调用BrandMapper中的selectAll方法//获取SqlSessionSqlSession sqlSession = sqlSessionFactory.openSession();//获取MapperBrandMapper brandMapper = sqlSession.getMapper(BrandMapper.class);//调用方法List<Brand> brands = brandMapper.selectAll();sqlSession.close();return brands;}
}

2.5 编写Servlet

package com.itheima.web;import com.itheima.pojo.Brand;
import com.itheima.service.BrandService;import javax.servlet.*;
import javax.servlet.http.*;
import javax.servlet.annotation.*;
import java.io.IOException;
import java.util.List;@WebServlet("/selectAllServlet")
public class SelectAllServlet extends HttpServlet {//创建这个服务private  BrandService service = new BrandService();@Overrideprotected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {//1. 调用BrandService完成查询List<Brand> brands = service.selectAll();//2. 存入request域中request.setAttribute("brands",brands);//3. 转发到brand.jsprequest.getRequestDispatcher("/brand.jsp").forward(request,response);}@Overrideprotected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {this.doGet(request, response);}
}

2.4 编写brand.jsp页面

<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core"%>
<%@ page isELIgnored="false" %>
<%@ page contentType="text/html;charset=UTF-8" language="java" %><!DOCTYPE html>
<html lang="en">
<head><meta charset="UTF-8"><title>Title</title>
</head>
<body>
<input type="button" value="新增"><br>
<hr>
<table border="1" cellspacing="0" width="800"><tr><th>序号</th><th>品牌名称</th><th>企业名称</th><th>排序</th><th>品牌介绍</th><th>状态</th><th>操作</th></tr><c:forEach items="${brands}" var="brand" varStatus="status"><tr align="center">
<%--      <td>${brand.id}</td>--%><td>${brand.id}</td><td>${brand.brandName}</td><td>${brand.companyName}</td><td>${brand.ordered}</td><td>${brand.description}</td><c:if test="${brand.status==1}"><td>启用</td></c:if><c:if test="${brand.status==0}"><td>禁止</td></c:if><td><a href="/brand-demo/selectByIdServlet?id=${brand.id}">修改</a> <a href="#">删除</a></td></tr></c:forEach></table></body>
</html>

2.5 测试

3.添加

3.1 编写BrandMapper接口 添加方法

//添加@Insert("insert into tb_brand values(null,#{brandName},#{companyName},#{ordered},#{description},#{status})")void add(Brand brand);

3.2 编写服务

public class BrandService {SqlSessionFactory sqlSessionFactory =SqlSessionFactoryUtils.getSqlSessionFactory();//添加数据public void add(Brand brand){//调用BrandMapper中的selectAll方法//获取SqlSessionSqlSession sqlSession = sqlSessionFactory.openSession();//获取MapperBrandMapper brandMapper = sqlSession.getMapper(BrandMapper.class);//调用方法brandMapper.add(brand);//提交事务sqlSession.commit();sqlSession.close();}
}

3.3 改写Brand.jsp页面，添加新增按钮，并跳转到新的jsp页面（addBrand页面）

<%--Created by IntelliJ IDEA.User: 11445Date: 2023/8/18Time: 20:31To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %><!DOCTYPE html>
<html lang="en"><head><meta charset="UTF-8"><title>添加品牌</title>
</head>
<body>
<h3>添加品牌</h3>
<form action="" method="post">品牌名称：<input name="brandName"><br>企业名称：<input name="companyName"><br>排序：<input name="ordered"><br>描述信息：<textarea rows="5" cols="20" name="description"></textarea><br>状态：<input type="radio" name="status" value="0">禁用<input type="radio" name="status" value="1">启用<br><input type="submit" value="提交">
</form>
</body>
</html>

3.4 编写Servlet

在 web 包下创建 AddServlet 的 servlet ，该 servlet 的逻辑如下:

• 设置处理post请求乱码的字符集
• 接收客户端提交的数据
• 将接收到的数据封装到 Brand 对象中
• 调用 BrandService 的 add() 方法进行添加的业务逻辑处理
• 跳转到 selectAllServlet 资源重新查询数据

package com.itheima.web;import com.itheima.pojo.Brand;
import com.itheima.service.BrandService;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 java.io.IOException;@WebServlet("/addServlet")
public class AddServlet extends HttpServlet {private BrandService service = new BrandService();@Overrideprotected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {//处理post请求的乱码问题req.setCharacterEncoding("utf-8");//1. 接收表单提交的数据，封装为一个Brand对象String brandName = req.getParameter("brandName");String companyName = req.getParameter("companyName");String ordered = req.getParameter("ordered");String description = req.getParameter("description");String status = req.getParameter("status");//封装为一个Brand对象Brand brand = new Brand();brand.setBrandName(brandName);brand.setCompanyName(companyName);brand.setOrdered(Integer.parseInt(ordered));brand.setDescription(description);brand.setStatus(Integer.parseInt(status));//2. 调用service 完成添加service.add(brand);//3. 转发到查询所有Servletreq.getRequestDispatcher("/selectAllServlet").forward(req,resp);}@Overrideprotected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {this.doGet(req,resp);}
}

3.5 测试

4.修改/回显

在该修改页面我们可以看到将 编辑 按钮所在行的数据 回显 到表单，然后需要修改那个数据在表单中进行修改，然后点击 提交 的按钮将数据提交到后端，后端再将数据存储到数据库中。

---

4.1 回显数据

//编写BrandMapper接口 添加方法
//回显，根据id查询@Select("select * from tb_brand where id = #{id}}")@ResultMap("brandResultMap")Brand selectById(int id);

//编写服务
import java.util.List;public class BrandService {SqlSessionFactory sqlSessionFactory =SqlSessionFactoryUtils.getSqlSessionFactory();public Brand selectById(int id){//调用BrandMapper中的selectById方法//获取SqlSessionSqlSession sqlSession = sqlSessionFactory.openSession();//获取MapperBrandMapper brandMapper = sqlSession.getMapper(BrandMapper.class);//调用方法Brand brand = brandMapper.selectById(id);sqlSession.close();return brand;}
}

编写servlet方法
package com.itheima.web;import com.itheima.pojo.Brand;
import com.itheima.service.BrandService;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 java.io.IOException;
import java.util.List;@WebServlet("/selectByIdServlet")
public class SelectByIdServlet extends HttpServlet {//创建这个服务private BrandService service = new BrandService();@Overrideprotected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {//接受idString id = req.getParameter("id");//1. 调用BrandService完成查询Brand brand = service.selectById(Integer.parseInt(id));//2. 存入request域中req.setAttribute("brand",brand);//3. 转发到brand.jspreq.getRequestDispatcher("/update.jsp").forward(req,resp);}@Overrideprotected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {this.doPost(req, resp);}
}

//编写update xml
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core"%>
<%@ page isELIgnored="false" %>
<%@ page contentType="text/html;charset=UTF-8" language="java" %><!DOCTYPE html>
<html lang="en"><head><meta charset="UTF-8"><title>修改品牌</title>
</head>
<body>
<h3>修改品牌</h3>
<form action="/updateServlet" method="post"><%--隐藏域，提交id--%><input type="hidden" name="id" value="${brand.id}">品牌名称：<input name="brandName" value="${brand.brandName}"><br>企业名称：<input name="companyName" value="${brand.companyName}"><br>排序：<input name="ordered" value="${brand.ordered}"><br>描述信息：<textarea rows="5" cols="20" name="description">${brand.description} </textarea><br>状态：<c:if test="${brand.status == 0}"><input type="radio" name="status" value="0" checked>禁用<input type="radio" name="status" value="1">启用<br></c:if><c:if test="${brand.status == 1}"><input type="radio" name="status" value="0" >禁用<input type="radio" name="status" value="1" checked>启用<br></c:if><input type="submit" value="提交">
</form>
</body>
</html>

修改Brand.jsp的修改连接地址

效果

4.2 修改数据

//修改
@Update(“update tb_brand set brand_name = #{brandName},company_name = #{companyName},ordered =\n” +
“#{ordered},description = #{description},status = #{status} where id = #{id}”)
void update(Brand brand);

//    修改public void update(Brand brand){//调用BrandMapper中的selectById方法//获取SqlSessionSqlSession sqlSession = sqlSessionFactory.openSession();//获取MapperBrandMapper brandMapper = sqlSession.getMapper(BrandMapper.class);//调用方法brandMapper.update(brand);//提交sqlSession.commit();sqlSession.close();}

@WebServlet("/updateServlet")
public class UpdateServlet extends HttpServlet {//创建这个服务private BrandService service = new BrandService();@Overrideprotected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {//处理post请求的乱码问题req.setCharacterEncoding("utf-8");//1. 接收表单提交的数据，封装为一个Brand对象String id = req.getParameter("id");String brandName = req.getParameter("brandName");String companyName = req.getParameter("companyName");String ordered = req.getParameter("ordered");String description = req.getParameter("description");String status = req.getParameter("status");//封装为一个Brand对象Brand brand = new Brand();brand.setId(Integer.parseInt(id));brand.setBrandName(brandName);brand.setCompanyName(companyName);brand.setOrdered(Integer.parseInt(ordered));brand.setDescription(description);brand.setStatus(Integer.parseInt(status));//2. 调用service 完成添加service.update(brand);//3. 转发到查询所有Servletreq.getRequestDispatcher("/selectAllServlet").forward(req,resp);}@Overrideprotected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {this.doGet(req,resp);}
}

5. 删除

   //删除@Delete("delete from tb_brand where id = #{id}")void deleteById(int id);

  public void deleteById(int id){SqlSession sqlSession = sqlSessionFactory.openSession();BrandMapper brandMapper = sqlSession.getMapper(BrandMapper.class);brandMapper.deleteById(id);sqlSession.commit();sqlSession.close();}

@WebServlet("/deleteByIdServlet")
public class DeleteByIdServlet extends HttpServlet {BrandService service = new BrandService();@Overrideprotected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {String id = req.getParameter("id");service.deleteById(Integer.parseInt(id));req.getRequestDispatcher("/selectAllServlet").forward(req,resp);}@Overrideprotected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {this.doPost(req, resp);}
}