springboot整合mybatis，pagehelper分页

1. 多环境配置
   默认使用application.yml的配置，其他环境 application-{profile}.yml
   开发环境：application-dev.yml
   测试环境：application-test.yml
   生产环境：application-prod.yml

2. 添加依赖
   参考 https://github.com/abel533/MyBatis-Spring-Boot

        <!--mybatis-->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <scope>runtime</scope>
        </dependency>
        <!--mybatis 和下面版本需要匹配-->
        <dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId>
            <version>1.3.1</version>
        </dependency>
        <!--mapper-->
        <dependency>
            <groupId>tk.mybatis</groupId>
            <artifactId>mapper-spring-boot-starter</artifactId>
            <version>2.0.3</version>
        </dependency>
        <!--pagehelper-->
        <dependency>
            <groupId>com.github.pagehelper</groupId>
            <artifactId>pagehelper-spring-boot-starter</artifactId>
            <version>1.3.0</version>
        </dependency>

3. 配置文件

spring:
  datasource:
    username: 
    password: 
    url: jdbc:mysql://127.0.0.1:3306/pay?useUnicode=true&characterEncoding=utf-8&useSSL=true&serverTimezone=UTC
    driver-class-name: com.mysql.cj.jdbc.Driver

mybatis:
    type-aliases-package: com.baoxian.entity
    mapper-locations: classpath:mapper/*.xml
    #配置驼峰下划线
    configuration:
      map-underscore-to-camel-case: true
      log-impl: org.apache.ibatis.logging.stdout.StdOutImpl

pagehelper:
    helperDialect: mysql
    reasonable: true
    supportMethodsArguments: true
    params: count=countSql

4. dao层，测试数据库连接是否成功

/**
 * 账单
 */
public interface PayBillDao extends Mapper<PayBill> {
    /**
     * 测试数据库连接
     * @return
     */
    @Select("SELECT count(*) FROM pay_bill ")
    Integer countPayBill();
}

mapper

<?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.baoxian.dao.PayBillDao">
</mapper>