使用idea集成SpringBoot和Mybatis

1.新建一个Spring Initializr项目

建好后的pom如下：

<?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>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.3.3.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.zgjy</groupId>
    <artifactId>dataserver</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>dataserver</name>
    <description>Demo project for Spring Boot</description>

    <properties>
        <java.version>1.8</java.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-jdbc</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId>
            <version>2.1.3</version>
        </dependency>

        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <scope>runtime</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
            <exclusions>
                <exclusion>
                    <groupId>org.junit.vintage</groupId>
                    <artifactId>junit-vintage-engine</artifactId>
                </exclusion>
            </exclusions>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>

</project>

2.修改配置文件

本文不使用application.properties文件 而使用更加简洁的application.yml文件。将resource文件夹下原有的application.properties文件删除，创建application.yml配置文件（备注：其实SpringBoot底层会把application.yml文件解析为application.properties），本文创建了两个yml文件（application.yml和application-dev.yml），分别来看一下内容
application.yml

spring:
  profiles:
    active: dev

application-dev.yml

server:
  port: 8080

spring:
  datasource:
    username: root
    password: 111111
    url: jdbc:mysql://localhost:3306/general_control_platform?useUnicode=true&characterEncoding=utf-8&useSSL=true&serverTimezone=UTC
    driver-class-name: com.mysql.jdbc.Driver

mybatis:
  mapper-locations: classpath:mapping/*Mapping.xml
  type-aliases-package: com.example.entity

#showSql
logging:
  level:
    com:
      example:
        mapper : debug

两个文件的意思是：
在项目中配置多套环境的配置方法。
因为现在一个项目有好多环境，开发环境，测试环境，准生产环境，生产环境，每个环境的参数不同，所以我们就可以把每个环境的参数配置到yml文件中，这样在想用哪个环境的时候只需要在主配置文件中将用的配置文件写上就行如application.yml

笔记：在Spring Boot中多环境配置文件名需要满足application-{profile}.yml的格式，其中{profile}对应你的环境标识，比如：

application-dev.yml：开发环境
application-test.yml：测试环境
application-prod.yml：生产环境
至于哪个具体的配置文件会被加载，需要在application.yml文件中通过spring.profiles.active属性来设置，其值对应{profile}值。

3.创建实体类实现业务流程

创建包controller、entity、mapper、service。resources下创建mapping文件夹，用于写sql语句，也可以用注解的方式直接写在mapper文件里。下面直接贴代码
数据库表结构

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;

entity.java

package com.zgjy.entity;

public class User {
    private Integer id;
    private String userName;
    private String passWord;
    private String realName;

    public User(Integer id, String userName, String passWord, String realName) {
        this.id = id;
        this.userName = userName;
        this.passWord = passWord;
        this.realName = realName;
    }

    @Override
    public String toString() {
        return "User{" +
                "id=" + id +
                ", userName='" + userName + '\'' +
                ", passWord='" + passWord + '\'' +
                ", realName='" + 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;
    }
}

UserController.java

package com.zgjy.controller;

import com.zgjy.service.UserService;
import org.springframework.beans.factory.annotation.Autowired;
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 {
    @Autowired
    private UserService userService;

    @RequestMapping("getUser/{id}")
    public String getUser(@PathVariable int id){
        return userService.Sel(id).toString();
    }
}

UserService.java

package com.zgjy.service;

import com.zgjy.entity.User;
import com.zgjy.mapper.UserMapper;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

@Service
public class UserService {
    @Autowired
    UserMapper userMapper;

    public User Sel(int id){
        return userMapper.Sel(id);
    }
}

UserMapper.java

package com.zgjy.mapper;

import com.zgjy.entity.User;
import org.springframework.stereotype.Repository;

@Repository
public interface UserMapper {
    User Sel(int id);
}

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.zgjy.mapper.UserMapper">

    <resultMap id="BaseResultMap" type="com.zgjy.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.zgjy.entity.User">
        select * from user where id = #{id}
    </select>

</mapper>

最终框架结构

完成以上，下面在启动类里加上注解用于给出需要扫描的mapper文件路径@MapperScan("com.example.mapper")

package com.zgjy.controller;

import com.zgjy.service.UserService;
import org.springframework.beans.factory.annotation.Autowired;
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 {
    @Autowired
    private UserService userService;

    @RequestMapping("getUser/{id}")
    public String getUser(@PathVariable int id){
        return userService.Sel(id).toString();
    }
}

最后启动，浏览器输入地址：http://localhost:8080/testBoot/getUser/1

最后给个番外篇如何更改启动时显示的字符拼成的字母，就是更改下图标红框的地方

只需要在resources下新建一个txt文件就可以，命名为banner.txt，那这种字符该怎么拼出来呢，下面推荐一个网址，有这种工具，链接传送门：字母转字符。如下：

直接输入要生成的字母，系统会自动转换，然后复制下面转换好的字符到新建的banner.txt文件中，重新启动项目就可以了。