MVC模式和三层架构

MVC模式

MVC分层开发模式

  • MVC是一种分层开发的模式，其中： :::info 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，调用模型和视图 ::: image.png

    MVC好处

  • 职责单一，互不影响

  • 有利于分工协作

  • 有利于组件重用

    三层架构

    三层架构（图文）
    image.png

    MVC模式和三层架构图

    image.png

    案例练习

    image.png

    准备环境

  • 创建新的模块 brand_demo,引入坐标

  • 创建三层架构的包结构
  • 数据库表 tb_brand
  • 实体类 Brand

  • MyBatis 基础环境 :::info Mybatis - config.xml
    BrandMapper.xml
    BrandMapper接口 :::

    建立新模块项目

    :::info brand_demo ::: image.png

    pom引入需要坐标

    ```java

    org.mybatis mybatis 3.5.5 mysql mysql-connector-java 5.1.36 
  1. <dependency>
  2.   <groupId>javax.servlet</groupId>
  3.   <artifactId>javax.servlet-api</artifactId>
  4.   <version>3.1.0</version>
  5.   <scope>provided</scope>
  6. </dependency>
  8. <dependency>
  9.   <groupId>javax.servlet.jsp</groupId>
  10.   <artifactId>jsp-api</artifactId>
  11.   <version>2.2</version>
  12.   <scope>provided</scope>
  13. </dependency>
  15. <!--        jstl-->
  16. <dependency>
  17.   <groupId>jstl</groupId>
  18.   <artifactId>jstl</artifactId>
  19.   <version>1.2</version>
  20. </dependency>
  23. <dependency>
  24.   <groupId>taglibs</groupId>
  25.   <artifactId>standard</artifactId>
  26.   <version>1.1.2</version>
  27. </dependency>

  1. <a name="p0EUH"></a>
  2. ### pom引入tomcat插件
  3. ```java
  4.   <build>
  5.     <plugins>
  6.       <plugin>
  7.         <groupId>org.apache.tomcat.maven</groupId>
  8.         <artifactId>tomcat7-maven-plugin</artifactId>
  9.         <version>2.2</version>
  10.       </plugin>
  11.     </plugins>
  12.   </build>

创建三层架构包结构

:::info com.taotao.web
com.taotao.service
com.taotao.mapper
com.taotao.pojo
com.taotao.util :::

使用数据库

:::info 仍然使用mybatis数据库中的tb_brand表
image.png ::: image.png

Brand实体类

  1. package com.taotao.pojo;
  3. /**
  4.  * create by 刘鸿涛
  5.  * 2022/3/29 16:19
  6.  */
  8. public class Brand {
  9.     private Integer id;
  10.     private String brand_name;
  11.     private String company_name;
  12.     private Integer ordered;
  13.     private String description;
  14.     private Integer status;
  16.     public Brand(){
  18.     }
  20.     public Brand(Integer id, String brand_name, String company_name, Integer ordered, String description, Integer status) {
  21.         this.id = id;
  22.         this.brand_name = brand_name;
  23.         this.company_name = company_name;
  24.         this.ordered = ordered;
  25.         this.description = description;
  26.         this.status = status;
  27.     }
  29.     public Integer getId() {
  30.         return id;
  31.     }
  33.     public void setId(Integer id) {
  34.         this.id = id;
  35.     }
  37.     public String getBrand_name() {
  38.         return brand_name;
  39.     }
  41.     public void setBrand_name(String brand_name) {
  42.         this.brand_name = brand_name;
  43.     }
  45.     public String getCompany_name() {
  46.         return company_name;
  47.     }
  49.     public void setCompany_name(String company_name) {
  50.         this.company_name = company_name;
  51.     }
  53.     public Integer getOrdered() {
  54.         return ordered;
  55.     }
  57.     public void setOrdered(Integer ordered) {
  58.         this.ordered = ordered;
  59.     }
  61.     public String getDescription() {
  62.         return description;
  63.     }
  65.     public void setDescription(String description) {
  66.         this.description = description;
  67.     }
  69.     public Integer getStatus() {
  70.         return status;
  71.     }
  73.     public void setStatus(Integer status) {
  74.         this.status = status;
  75.     }
  77.     @Override
  78.     public String toString() {
  79.         return "Brand{" +
  80.                 "id=" + id +
  81.                 ", brand_name='" + brand_name + '\'' +
  82.                 ", company_name='" + company_name + '\'' +
  83.                 ", ordered=" + ordered +
  84.                 ", description='" + description + '\'' +
  85.                 ", status=" + status +
  86.                 '}';
  87.     }
  88. }

xml配置文件

mybatis-config.xml

  1. <?xml version="1.0" encoding="UTF-8" ?>
  2. <!DOCTYPE configuration
  3.         PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
  4.         "http://mybatis.org/dtd/mybatis-3-config.dtd">
  5. <configuration>
  6. <!--    起别名-->
  7.     <typeAliases>
  8.         <package name="com.taotao.pojo"/>
  9.     </typeAliases>
  10.     <environments default="development">
  11.         <environment id="development">
  12.             <transactionManager type="JDBC"/>
  13.             <dataSource type="POOLED">
  14.                 <property name="driver" value="com.mysql.jdbc.Driver"/>
  15.                 <property name="url" value="jdbc:mysql:///mybatis?useSSL=false&amp;useServerPrepStmts=true"/>
  16.                 <property name="username" value="root"/>
  17.                 <property name="password" value="12345"/>
  18.             </dataSource>
  19.         </environment>
  20.     </environments>
  22.     <mappers>
  23. <!--        扫描mapper-->
  24.         <package name="com/taotao/mapper"/>
  25.     </mappers>
  26. </configuration>

创建映射文件夹

:::info resources 下的 com.taotao.mapper :::

创建映射文件

:::info BrandMapper.xml :::

  1. <?xml version="1.0" encoding="UTF-8" ?>
  2. <!DOCTYPE mapper
  3.         PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
  4.         "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
  5. <mapper namespace="com.taotao.mapper.BrandMapper">
  7.     <select id="selectAll" resultType="com.taotao.pojo.Brand">
  8.         select * from tb_brand
  9.     </select>
  10. </mapper>

创建BrandMapper接口

:::info com.taotao.mapper.BrandMapper.java :::

  1. package com.taotao.mapper;
  3. /**
  4.  * create by 刘鸿涛
  5.  * 2022/3/29 16:12
  6.  */
  7. public interface BrandMapper {
  9. }

完成“查询所有”功能

流程分析

image.png

  1. package com.taotao.mapper;
  3. import com.taotao.pojo.Brand;
  4. import org.apache.ibatis.annotations.Select;
  6. import java.util.List;
  8. /**
  9.  * create by 刘鸿涛
  10.  * 2022/3/29 16:12
  11.  */
  12. public interface BrandMapper {
  13.     @Select("select * from tb_brand")
  14.     List<Brand> selectAll();
  15. }

编写service

:::info 新建BrandService.java :::

  1. package com.taotao.service;
  3. import com.taotao.mapper.BrandMapper;
  4. import com.taotao.pojo.Brand;
  5. import com.taotao.util.SqlSessionfactoryUtils;
  6. import org.apache.ibatis.session.SqlSession;
  7. import org.apache.ibatis.session.SqlSessionFactory;
  9. import java.util.List;
  11. /**
  12.  * create by 刘鸿涛
  13.  * 2022/3/29 16:59
  14.  */
  15. @SuppressWarnings({"all"})
  16. public class BrandService {
  18.     /**
  19.      * 查询所有
  20.      * @return
  21.      */
  22.     public List<Brand> selectAll(){
  23.         //调用BrandMapper.selectAll()
  25.         SqlSessionFactory factory = SqlSessionfactoryUtils.getSqlSessionFactory();
  27.         //2.获取sqlSession
  28.         SqlSession sqlSession = factory.openSession();
  30.         //3.获取BrandMapper
  31.         BrandMapper mapper = sqlSession.getMapper(BrandMapper.class);
  33.         //4.调用方法
  34.         List<Brand> brands = mapper.selectAll();
  36.         //5.关闭资源
  37.         sqlSession.close();
  39.         return brands;
  40.     }
  41. }

编写index.html

  1. <!DOCTYPE html>
  2. <html lang="en">
  3. <head>
  4.     <meta charset="UTF-8">
  5.     <title>Title</title>
  6. </head>
  7. <body>
  8. <a href="/brand_demo/selectAllServlet">查询所有</a>
  9. </body>
  10. </html>

编写Servlet

  1. package com.taotao.web;
  3. import com.taotao.pojo.Brand;
  4. import com.taotao.service.BrandService;
  6. import javax.servlet.ServletException;
  7. import javax.servlet.annotation.WebServlet;
  8. import javax.servlet.http.HttpServlet;
  9. import javax.servlet.http.HttpServletRequest;
  10. import javax.servlet.http.HttpServletResponse;
  11. import java.io.IOException;
  12. import java.util.List;
  14. /**
  15.  * create by 刘鸿涛
  16.  * 2022/3/29 17:31
  17.  */
  18. @WebServlet("/selectAllServlet")
  19. public class selectAllServlet extends HttpServlet {
  20.     private BrandService service = new BrandService();
  21.     @Override
  22.     protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
  24.         //1.调用BrandService完成查询
  26.         List<Brand> brands = service.selectAll();
  28.         //2.存入request域中
  29.         req.setAttribute("brands",brands);
  31.         //3.转发到brand.jsp
  32.         req.getRequestDispatcher("/brand.jsp").forward(req,resp);
  34.     }
  36.     @Override
  37.     protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
  38.         this.doGet(req, resp);
  39.     }
  40. }

编写JSP

  1. <%--
  2.   Created by IntelliJ IDEA.
  3.   User: guigui
  4.   Date: 2022/3/29
  5.   Time: 10:32
  6.   To change this template use File | Settings | File Templates.
  7. --%>
  8. <%@ page contentType="text/html;charset=UTF-8" language="java" %>
  9. <%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core"%>
  10. <%@ page isELIgnored="false" %>
  12. <html>
  13. <head>
  14.     <title>Title</title>
  15. </head>
  16. <body>
  18. <input type="button" value="新增"><br>
  19. <hr>
  20. <table border="1" cellspacing="0" width="800">
  21.     <tr>
  22.         <th>序号</th>
  23.         <th>品牌名称</th>
  24.         <th>公司名称</th>
  25.         <th>价格</th>
  26.         <th>描述</th>
  27.         <th>状态</th>
  28.     </tr>
  30. <c:forEach items="${brands}" var="brand" varStatus="status">
  31.     <tr align="center">
  32.         <td>${brand.id}</td>
  33.         <td>${brand.brand_name}</td>
  34.         <td>${brand.company_name}</td>
  35.         <td>${brand.ordered}</td>
  36.         <td>${brand.description}</td>
  37.         <c:if test="${brand.status == 1}">
  38.             <td>启用</td>
  39.         </c:if>
  41.         <c:if test="${brand.status != 1}">
  42.             <td>禁用</td>
  43.         </c:if>
  44.     </tr>
  45. </c:forEach>
  47. </table>
  48. </body>
  49. </html>

运行测试

:::info 因为数据库字段名与 实体类 字段名不同，所以没有显示brandName和companyName ::: image.png

显示品牌名称、公司名称resultMap

mybatis开发sql

:::info 使用resultMap :::

编写BrandMapper.xml

  1. <?xml version="1.0" encoding="UTF-8" ?>
  2. <!DOCTYPE mapper
  3.         PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
  4.         "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
  5. <mapper namespace="com.taotao.mapper.BrandMapper">
  7.     <select id="selectAll" resultMap="brandResultMap">
  8.         select * from tb_brand
  9.     </select>
  11.     <resultMap id="brandResultMap" type="brand">
  12.         <result column="brandName" property="brand_name"></result>
  13.         <result column="companyName" property="company_name"></result>
  14.     </resultMap>
  15. </mapper>

编写BrandMapper.java

:::info 为BrandMapper.java加上@ResultMap注解 :::

  1. package com.taotao.mapper;
  3. import com.taotao.pojo.Brand;
  4. import org.apache.ibatis.annotations.ResultMap;
  5. import org.apache.ibatis.annotations.Select;
  7. import java.util.List;
  9. /**
  10.  * create by 刘鸿涛
  11.  * 2022/3/29 16:12
  12.  */
  13. public interface BrandMapper {
  14. //    @Select("select * from tb_brand")
  15. //    @ResultMap("brandResultMap")
  16.     List<Brand> selectAll();
  17. }

测试运行

image.png

注解开发SQL

编写BrandMapper.xml

  1. <?xml version="1.0" encoding="UTF-8" ?>
  2. <!DOCTYPE mapper
  3.         PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
  4.         "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
  5. <mapper namespace="com.taotao.mapper.BrandMapper">
  7. <!--    <select id="selectAll" resultMap="brandResultMap">-->
  8. <!--        select * from tb_brand-->
  9. <!--    </select>-->
  11.     <resultMap id="brandResultMap" type="brand">
  12.         <result column="brandName" property="brand_name"></result>
  13.         <result column="companyName" property="company_name"></result>
  14.     </resultMap>
  15. </mapper>

编写BrandMapper.java

  1. package com.taotao.mapper;
  3. import com.taotao.pojo.Brand;
  4. import org.apache.ibatis.annotations.ResultMap;
  5. import org.apache.ibatis.annotations.Select;
  7. import java.util.List;
  9. /**
  10.  * create by 刘鸿涛
  11.  * 2022/3/29 16:12
  12.  */
  13. public interface BrandMapper {
  14.     @Select("select * from tb_brand")
  15.     @ResultMap("brandResultMap")
  16.     List<Brand> selectAll();
  17. }

测试运行

image.png