YML基本配置 

#端口配置
server:port: 8090#配置数据源
spring:datasource:#如果使用高版本驱动 则添加cjdriver-class-name: com.mysql.cj.jdbc.Driverurl: jdbc:mysql://127.0.0.1:3306/jt?serverTimezone=GMT%2B8&useUnicode=true&characterEncoding=utf8&autoReconnect=true&allowMultiQueries=trueusername: rootpassword: root#Spring整合Mybatis
mybatis:#定义别名包type-aliases-package: com.jt.pojo#导入映射文件mapper-locations: classpath:/mappers/*.xml#开启驼峰映射configuration:map-underscore-to-camel-case: true

映射文件基础写法 

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapperPUBLIC "-//mybatis.org//DTD Mapper 3.0//EN""http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.jt.mapper.UserMapper"><!--Oracle中 ;号必定报错  不要加;号  --><select id="findAll" resultType="com.jt.pojo.User">select * from demo_user</select></mapper>