在idea中创建好项目后，添加web项目
然后打开idea的setting，跳转到下面的页面，下载maven插件。
出现下面的选项，才正确。
添加好web项目后，打开pom文件，添加相应的依赖：
<?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>MVCCase</artifactId>
<version>1.0-SNAPSHOT</version>
<packaging>war</packaging>
<properties>
<maven.compiler.source>8</maven.compiler.source>
<maven.compiler.target>8</maven.compiler.target>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
</properties>
<dependencies>
<!-- 下面俩个依赖是写servlet的-->
<dependency>
<groupId>javax.servlet</groupId>
<artifactId>javax.servlet-api</artifactId>
<version>3.1.0</version>
<scope>provided</scope><!--provided在编译和测试环境有效 -->
</dependency>
<dependency>
<groupId>javax.servlet.jsp</groupId>
<artifactId>jsp-api</artifactId>
<version>2.2</version>
<scope>provided</scope>
</dependency>
<!-- 下面俩个依赖是连接数据库时用到的-->
<dependency>
<groupId>org.mybatis</groupId>
<artifactId>mybatis</artifactId>
<version>3.5.5</version>
</dependency>
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>8.0.21</version>
</dependency>
<!-- 下面俩个依赖是工具依赖，在写jsp时会用到-->
<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>
<configuration>
<port>8080</port>
<path>/</path>
</configuration>
</plugin>
</plugins>
</build>
</project>千万别忘了，写上<packaging>war</packaging> 把打包方式改成打war包。
下面图片是要进行操作的数据库信息:
因为操作数据库过程中用到了mybatis，所以需要配置相应的xml文件，详细的配置过程在前面的Mybatis简化JDBC开发文章中写过。下面这是brandMapper.xml的内容。
<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper
PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
"https://mybatis.org/dtd/mybatis-3-mapper.dtd">
<!--<mapper namespace="test">-->
<mapper namespace="org.example.Mapper.brandMapper">
<resultMap id="brandResultMap" type="brand">
<result column="brand_name" property="brandName"></result>
<result column="company_name" property="companyName"></result>
</resultMap>
</mapper>然后创建对应的实体类pojo，接口方法类Mapper和方法实现类service。
pojo实体类：
package org.example.pojo;
public class brand {
private Integer id;
private String brandName;
private String companyName;
private Integer ordered;
private String description;
private Integer status;
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 brand() {
}
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;
}
}
接口方法类Mapper
先写一个查询所有的方法，因为此处需要实现的功能比较简单，所以用注解就行了。
public interface brandMapper {
//查询全部
@Select("select * from db.brand")
@ResultMap("brandResultMap")
List<brand>selectAll();
}方法实现类service
import java.util.List;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.example.Mapper.brandMapper;
import org.example.pojo.brand;
import org.example.util.SqlSessionFactoryUtils;
public class brandService {
String resource = "mybatis-config.xml";
InputStream inputStream = null;
inputStream = Resources.getResourceAsStream(resource);
SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
//调用brandMapper中的selectAll方法。
public List<brand> selectAll(){
//获取session
SqlSession sqlSession = sqlSessionFactory.openSession();
brandMapper brandMapper = sqlSession.getMapper(brandMapper.class);
List<brand> brands = brandMapper.selectAll();
sqlSession.close();
return brands;
}
}下面让我们写展示brand信息的jsp页面：
注意：<%@ taglib prefix="c" uri="http://java.sun.com/jstl/core_rt" %>，只有声明该配置，才能应用pom文件中配置的工具jstl依赖。
jstl工具中有<c:foreach> 相当于Java中的for循环和<c:if>标签相当于Java语句中的if语句。
<%--
Created by IntelliJ IDEA.
User: quwenhao
Date: 2023/12/28
Time: 17:46
To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" isELIgnored="false" %>
<%@ taglib prefix="c" uri="http://java.sun.com/jstl/core_rt" %>
<html>
<head>
<title>Title</title>
</head>
<body>
<h1>${user.username},欢迎您</h1>
<input type="button" value="新增" id="addBrand"><br>
<hr>
<table border="1" cellspacing="0" width="800">
<tr>
<td>序号</td>
<td>品牌名称</td>
<td>企业名称</td>
<td>排序</td>
<td>品牌介绍</td>
<td>状态</td>
<td>操作</td>
</tr>
<c:forEach items="${brands}" var="brand" varStatus="Status">
<-- var 属性是为多个brands中的一个个体命名 varStatus是为每条信息前的序号命名，设置为index是序号从1开始递增-->
<tr align="center">
<%-- <td>${brand.id}</td>--%>
<td>${Status.index}</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 !=1}">
<td>禁用</td>
</c:if>
<td><a href="#">修改</a> <a href="#">删除</a> </td>
</c:forEach>
</table>
</body>
</html>
下面到了写jsp页面中信息的来源了 Servlet。新建一个Servlet
package org.example.web;
import javax.servlet.*;
import javax.servlet.http.*;
import javax.servlet.annotation.WebServlet;
import java.io.IOException;
import java.util.List;
import org.example.pojo.brand;
import org.example.service.brandService;
@WebServlet("/brandSelectAllService")
public class brandSelectAllService extends HttpServlet {
private brandService brandService=new brandService();
@Override
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
//1调用对应的brandService方法
List<brand> brands = brandService.selectAll();
//2存入request对象中
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);
}
}在该Servlet中调用前面声明的查询数据库的方法，获取数据库信息后，在将获取的brands数据转发到brand.jsp页面中。
然后我们可以写一个index.html文件来登陆brands
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>
</head>
<body>
<a href="/brandSelectAllService">登陆</a>
</body>
</html>点击登陆就会进入查询Servlet中，执行查询所有方法，然后在跳转到brands.jsp页面中展示信息。
下面来看看效果：
点击tomcat7:run 运行tomcat
出现这个后，就可以在浏览器中试着打开我们自己写的jsp了 .。打开浏览器输入网址http://localhost:8080/index.html，点击登陆就可以查询到数据库所有信息了。
