Change Servlet project to SSM project

将Servlet项目改为SSM（Spring Boot+Spring MVC+MyBATIS）项目.

1.先创建SSM项目.

2.Set up profiles for different platforms

2.1.Create profiles for different platforms

要求：The configuration file format for different platforms must conform to the specification.

2.2.在主配置文件中（application.yml）The runtime platform of the configuration project in

spring:
  profiles:
   active: dev

This can be done.

3.Configure the connected database and MyBatis 存储 xml 的路径

#开发环境的配置文件
spring:
  datasource:
    url: jdbc:mysql://127.0.0.1:3306/myblog2022?characterEncoding=utf8&useSSL=true
    username: root
    password: 12345678
    driver-class-name: com.mysql.cj.jdbc.Driver

#生产环境的配置文件
spring:
  datasource:
    url: jdbc:mysql://121.5.240.34:3306/myblog2022?characterEncoding=utf8&useSSL=true
    username: root
    password: 12345678
    driver-class-name: com.mysql.cj.jdbc.Driver

主配置文件：

#配置mybatis xml保存路径
mybatis:
  mapper-locations: classpath:mybatis/**Mapper.xml 

4.将servletAll front-end pages in ssm项目中的static目录中

5.Retrofit to implement business interface

重点操作MyBatis,
Manipulate two files：xxxMapper.java 的接口声明、xxxMapper.xml 实现SQL操作