在SpringBoot 1.X 中，spring-boot-starter-jdbc启动器中默认使用的是org.apache.tomcat.jdbc.pool.DataSource作为数据源
在SpringBoot 2.X 中，spring-boot-starter-jdbc启动器中默认使用的是com.zaxxer.hikari.HikariDataSource作为数据源

引入坐标依赖

<?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.zjw</groupId>
	<artifactId>springbootjdbc</artifactId>
	<version>0.0.1-SNAPSHOT</version>
	<name>springbootjdbc</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-web</artifactId>
		</dependency>
		<!--Thymeleaf-->
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-thymeleaf</artifactId>
		</dependency>
		<!--jdbc-->
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-jdbc</artifactId>
		</dependency>
		<!--mysql-->
		<dependency>
			<groupId>mysql</groupId>
			<artifactId>mysql-connector-java</artifactId>
			<version>8.0.15</version>
		</dependency>
		<!--druid-->
		<dependency>
			<groupId>com.alibaba</groupId>
			<artifactId>druid</artifactId>
			<version>1.1.12</version>
		</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>

配置application.properties文件

spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver
spring.datasource.url=jdbc:mysql://192.168.234.128/sb?useSSL=false&serverTimeZone=Shanghai/Asia
spring.datasource.username=root
spring.datasource.password=a@123456
#指定为Druid数据源,默认为HikariDataSource数据源
spring.datasource.type=com.alibaba.druid.pool.DruidDataSource

新建一个controller观察使用的是哪一个数据源

package com.zjw.controller;

import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.GetMapping;

import javax.annotation.Resource;
import javax.sql.DataSource;

@Controller
public class UsersController {

    @Resource
    private DataSource dataSource;

    @GetMapping("/showInfo")
    public String showInfo(){
        //观察使用的是哪个数据源
        System.out.println(this.dataSource.getClass());
        return "OK";
    }
}

打印结果：

class com.alibaba.druid.pool.DruidDataSource