2022.2.28 案例：利用三层架构，完成品牌数据的增删改查

最新推荐文章于 2022-07-09 18:19:20 发布

原创最新推荐文章于 2022-07-09 18:19:20 发布 · 809 阅读

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CC 4.0 BY-SA版权

文章标签：

#架构 #java #tomcat

本文通过一个案例详细介绍了如何运用三层架构（表现层、业务逻辑层、数据访问层）来实现品牌数据的增删改查功能。文章涉及了pom.xml配置、Brand实体类、Mapper接口及XML配置、Service业务处理、Servlet控制以及前后端交互的jsp页面，全面阐述了整个流程。

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准备环境
在这里插入图片描述
结构图如下：

pom.xml

<?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-demo1</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>
                <configuration>
                    <ignorePackaging>true</ignorePackaging>
                </configuration>
                <version>2.2</version>
            </plugin>
        </plugins>
    </build>

</project>

Brand.java

package com.itheima.pojo;
/**
 * 品牌实体类
 */
public class Brand {
    // id 主键
    private Integer id;
    // 品牌名称 
    private String brandName;
    // 企业名称
    private String companyName;
    // 排序字段
    private Integer ordered;
    // 描述信息
    private String description;
    // 状态：0：禁用  1：启用
    private Integer status;
    public Brand() {
    }
    public Brand(Integer id, String brandName, String companyName, String description) {
        this.id = id;
        this.brandName = brandName;
        this.companyName = companyName;
        this.description = description;
    }
    public Brand(Integer id, String brandName, String companyName, Integer ordered, String description, Integer status) {
        this.id = id;
        this.brandName = brandName;
        this.companyName = companyName;
        this.ordered = ordered;
        this.description = description;
        this.status = status;
    }
    public Integer getId() {
        return id;
    }
    public void setId(Integer id) {
        this.id = id;
    }
    public String getBrandName() {
        return brandName;
    }
    public void setBrandName(String brandName) {
        this.brandName = brandName;
    }
    public String getCompanyName() {
        return companyName;
    }
    public void setCompanyName(String companyName) {
        this.companyName = companyName;
    }
    public Integer getOrdered() {
        return ordered;
    }
    public void setOrdered(Integer ordered) {
        this.ordered = ordered;
    }
    public String getDescription() {
        return description;
    }
    public void setDescription(String description) {
        this.description = description;
    }
    public Integer getStatus() {
        return status;
    }
    public void setStatus(Integer status) {
        this.status = status;
    }
    @Override
    public String toString() {
        return "Brand{" +
                "id=" + id +
                ", brandName='" + brandName + '\'' +
                ", companyName='" + companyName + '\'' +
                ", ordered=" + ordered +
                ", description='" + description + '\'' +
                ", status=" + status +
                '}';
    }
}

BrandMapper.xml

<?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">
<mapper namespace="com.itheima.mapper.BrandMapper">

</mapper>

BrandMapper.java

package com.itheima.mapper;
/**
 * @Description: TODO
 * @author: scott
 * @date: 2022年02月25日 15:54
 */
public class BrandMapper {
}

增加操作

BrandMapper.java

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

BrandService.java

    public void add(Brand brand){
        //获取Session
        SqlSession sqlSession = factory.openSession();
        //获取BrandMapper
        BrandMapper mapper = sqlSession.getMapper(BrandMapper.class);
        mapper.add(brand);
        //提交事务
        sqlSession.commit();
        //释放资源
        sqlSession.close();
    }

AddServlet.java

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;

/**
 * @Description: TODO
 * @author: scott
 * @date: 2022年02月28日 14:14
 */
@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请求乱码问题
        req.setCharacterEncoding("utf-8");


        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));

        service.add(brand);
        //转发至查询所有
        req.getRequestDispatcher("/selectAllServlet").forward(req,resp);

    }

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

addBrand.jsp

<%@ 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="/brand-demo1/addServlet" 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>

修改功能

1.回显2.修改
BrandMapper.java

    /*根据id查询
    * */
    @Select("select * from tb_brand where id =#{id}")
    @ResultMap("brandResultMap")
    Brand selectById(int id);

    /*修改
    * */
    @Update("update tb_brand set brand_name= #{brandName}, company_name= #{companyName}, ordered= #{ordered}, description= #{description}, status= #{status} where id =#{id}")
    void update(Brand brand);

BrandService.java

   public Brand selectById(int id){
        //调用BrandMapper.selectAll()

        //获取Session
        SqlSession sqlSession = factory.openSession();
        //获取BrandMapper
        BrandMapper mapper = sqlSession.getMapper(BrandMapper.class);
        //调用方法
        Brand brand = mapper.selectById(id);

        sqlSession.close();
        return brand;

    }
    /*
    修改
    * */
    public void update(Brand brand){
        //调用BrandMapper.selectAll()

        //获取Session
        SqlSession sqlSession = factory.openSession();
        //获取BrandMapper
        BrandMapper mapper = sqlSession.getMapper(BrandMapper.class);
        //调用方法
        mapper.update(brand);
        sqlSession.commit();
        sqlSession.close();

    }

SelectByIdServlet.java

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;

/**
 * @Description: TODO
 * @author: scott
 * @date: 2022年02月25日 16:55
 */
@WebServlet("/selectByIdServlet")
public class SelectByIdServlet extends HttpServlet {
    private BrandService service =new BrandService();

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
     String id = req.getParameter("id");
     Brand brand = service.selectById(Integer.parseInt(id));
     req.setAttribute("brand",brand);
     req.getRequestDispatcher("/updateBrand.jsp").forward(req,resp);

    }

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

UpdateServlet.java

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;

/**
 * @Description: TODO
 * @author: scott
 * @date: 2022年02月25日 16:55
 */
@WebServlet("/updateServlet")
public class UpdateServlet extends HttpServlet {
    private BrandService service =new BrandService();

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

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        //处理post请求乱码问题
        req.setCharacterEncoding("utf-8");

        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));

        service.update(brand);
        //转发至查询所有
        req.getRequestDispatcher("/selectAllServlet").forward(req,resp);


    }
}

updateBrand.jsp

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<!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="/brand-demo1/updateServlet" method="post">

    <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>