springboot 集成 mybatis

1、第一步：引入依赖

<dependency>
    <groupId>org.mybatis.spring.boot</groupId>
    <artifactId>mybatis-spring-boot-starter</artifactId>
    <version>2.0.0</version>
</dependency>

<dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
</dependency>

2、application.yml

spring:
  datasource:
    driver-class-name: com.mysql.cj.jdbc.Driver
    url: jdbc:mysql://62.234.155.68:3306/account?characterEncoding=utf8&serverTimezone=UTC
    username: root
    password: ******

mybatis:
  type-aliases-package: com.example.springboot_allblue.bean
  mapper-locations: classpath:mapper/*Mapper.xml

此处要注意 username和password不是data-username和data-password，写错了，查询时提示连接不上数据库，调试了两个多小时才找到，血泪的教训

3、依次创建bean、mapper、service、controller代码包

 注意：启动类上需加上 @MapperScan("mapper包路径")

 mapper接口类上的注解为@mapper

4、在resource路径下创建mapper目录

 xml文件代码

<?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.springboot_allblue.mapper.UserMapper">
    <resultMap id="userMap" type="User">
        <id column="id" property="id"/>
        <result column="user_name" property="userName"/>
    </resultMap>

    <select id="selectAll" resultMap="userMap">
        select * from my_user
    </select>

</mapper>