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 configuration
        PUBLIC "-//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 mapper
        PUBLIC "-//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SqlSession
        SqlSession sqlSession = sqlSessionFactory.openSession();

        //获取Mapper
        BrandMapper 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();
    @Override
    protected 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.jsp
        request.getRequestDispatcher("/brand.jsp").forward(request,response);
    }

    @Override
    protected 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SqlSession
        SqlSession sqlSession = sqlSessionFactory.openSession();

        //获取Mapper
        BrandMapper 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: 11445
  Date: 2023/8/18
  Time: 20:31
  To 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();

    @Override
    protected 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Servlet
        req.getRequestDispatcher("/selectAllServlet").forward(req,resp);
    }

    @Override
    protected 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SqlSession
        SqlSession sqlSession = sqlSessionFactory.openSession();

        //获取Mapper
        BrandMapper 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();

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
    
    
        //接受id
        String 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.jsp
        req.getRequestDispatcher("/update.jsp").forward(req,resp);
    }

    @Override
    protected 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SqlSession
        SqlSession sqlSession = sqlSessionFactory.openSession();

        //获取Mapper
        BrandMapper 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();
    @Override
    protected 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Servlet
        req.getRequestDispatcher("/selectAllServlet").forward(req,resp);
    }

    @Override
    protected 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();
    @Override
    protected 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);
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
    
    
        this.doPost(req, resp);
    }
}