目的：创建一个新项目Jesus（基于idea2022），实现CRUD，该项目作为学习模版。

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STEP 1 项目创建

   1.1 新建Spring Initializr项目

  

   1.2 选择需要的依赖 springboot有2.7.2直接选272

  

STEP 2 配置更改

   2.1更改maven配置

   2.2 检查项目配置jdk、sdk、jre版本一致

   2.3 检查pom文件，Maven-Reload project构建下载包，不报红即可

   Maven的 Plugins 报红，执行命令mvn dependency:resolve-plugins，该命令的作用是：解决依赖关系，根据POM文件，下载或者更新该项目所依赖的库文件。
   pom文件会报版本不匹配，报错搜一下更新成适配版本就行了，下面是最终可用的pom文件。
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 https://maven.apache.org/xsd/maven-4.0.0.xsd"><modelVersion>4.0.0</modelVersion><groupId>com.example</groupId><artifactId>Jesus</artifactId><version>0.0.1-SNAPSHOT</version><name>Jesus</name><description>Jesus</description><parent><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-parent</artifactId><version>2.7.2</version><relativePath/> <!-- lookup parent from repository --></parent><properties><project.build.sourceEncoding>UTF-8</project.build.sourceEncoding><project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding><mybatis.spring.boot.version>2.1.3</mybatis.spring.boot.version><java.version>1.8</java.version><mysql.version>8.0.29</mysql.version><druid.version>1.2.6</druid.version><commons.lang.version>2.6</commons.lang.version></properties><dependencies><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-data-jdbc</artifactId></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-web-services</artifactId></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-test</artifactId><scope>test</scope></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-web</artifactId></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-aop</artifactId></dependency><dependency><groupId>org.springframework</groupId><artifactId>spring-context-support</artifactId></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-data-redis</artifactId></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-configuration-processor</artifactId><optional>true</optional></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-devtools</artifactId><optional>true</optional></dependency><dependency><groupId>org.mybatis.spring.boot</groupId><artifactId>mybatis-spring-boot-starter</artifactId><version>${mybatis.spring.boot.version}</version></dependency><dependency><groupId>commons-lang</groupId><artifactId>commons-lang</artifactId><version>${commons.lang.version}</version></dependency><dependency><groupId>mysql</groupId><artifactId>mysql-connector-java</artifactId><version>${mysql.version}</version></dependency><dependency><groupId>com.alibaba</groupId><artifactId>druid-spring-boot-starter</artifactId><version>${druid.version}</version></dependency><dependency><groupId>org.projectlombok</groupId><artifactId>lombok</artifactId><optional>true</optional></dependency></dependencies><build><plugins><plugin><groupId>org.springframework.boot</groupId><artifactId>spring-boot-maven-plugin</artifactId></plugin></plugins></build></project>

   2.4 删除properties文件，改用yaml配置文件

application.yml

spring:profiles:active: dev

application-dev.yml

server:port: 8080spring:datasource:username: root【数据库名】password: zxy000123【数据库密码】url: jdbc:mysql://localhost:3306/zxy【库名称】?useUnicode=true&characterEncoding=utf-8&useSSL=true&serverTimezone=UTCdriver-class-name: com.mysql.jdbc.Drivermybatis:mapper-locations: classpath:mapping/*Mapper.xmltype-aliases-package: com.example.entity
#showSql
logging:level:com:example:mapper : debug

   2.5 启动一下

STEP 3 实现业务CRUD

   3.1 库中建表

CREATE TABLE `user` (`id` int(32) NOT NULL AUTO_INCREMENT,`userName` varchar(32) NOT NULL,`passWord` varchar(50) NOT NULL,`realName` varchar(32) DEFAULT NULL,PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=3 DEFAULT CHARSET=utf8;

   3.2 项目结构

   新建controller、entity、mapper、service文件夹在com.example.jesusu下
   新建mapping在resurces下

   3.3 实体类、controller层、service层、mapper数据访问层、分别写代码

entity—User.java

package com.example.jesus.entity;public class User {private Integer id;private String userName;private String passWord;private String realName;public Integer getId() {return id;}public void setId(Integer id) {this.id = id;}public String getUserName() {return userName;}public void setUserName(String userName) {this.userName = userName;}public String getPassWord() {return passWord;}public void setPassWord(String passWord) {this.passWord = passWord;}public String getRealName() {return realName;}public void setRealName(String realName) {this.realName = realName;}@Overridepublic String toString() {return "User{" +"id=" + id +", userName='" + userName + '\'' +", passWord='" + passWord + '\'' +", realName='" + realName + '\'' +'}';}
}

Controller—UserController.java

package com.example.jesus.controller;import com.example.jesus.entity.User;
import com.example.jesus.service.UserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;@RestController
@RequestMapping("/testBoot")
public class UserController {@Autowiredprivate UserService userService;@RequestMapping("getUser/{id}")public String GetUser(@PathVariable int id){return userService.Sel(id).toString();}
}

Service—UserService.java

package com.example.jesus.service;import com.example.jesus.entity.User;
import com.example.jesus.mapper.UserMapper;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;@Service
public class UserService {@AutowiredUserMapper userMapper;public User Sel(int id){return userMapper.Sel(id);}
}

Mapper—UserMapper.java

package com.example.jesus.mapper;import com.example.jesus.entity.User;
import org.apache.ibatis.annotations.Select;
import org.springframework.stereotype.Repository;@Repository
public interface UserMapper {User Sel(int id);
}

Mapper—UserMapping.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.example.jesus.mapper.UserMapper"><resultMap id="BaseResultMap" type="com.example.entity.User"><result column="id" jdbcType="INTEGER" property="id" /><result column="userName" jdbcType="VARCHAR" property="userName" /><result column="passWord" jdbcType="VARCHAR" property="passWord" /><result column="realName" jdbcType="VARCHAR" property="realName" /></resultMap><select id="Sel" resultType="com.example.entity.User">select * from user where id = #{id}</select></mapper>

   3.4 启动类增加注解

   加上注解用于给出需要扫描的mapper文件路径
   @MapperScan(“com.example.mapper”)

package com.example.jesus;import org.mybatis.spring.annotation.MapperScan;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;@MapperScan("com.example.jesus.mapper") //扫描的mapper
@SpringBootApplication
public class JesusApplication {public static void main(String[] args) {SpringApplication.run(JesusApplication.class, args);System.out.println("启动Jesus项目成功");}}