1 DBCP

<dependency>
    <groupId>org.apache.commons</groupId>
    <artifactId>commons-dbcp2</artifactId>
    <version>2.9.0</version>
</dependency>

spring.datasource.url=jdbc:mysql://localhost:3306/mydb
spring.datasource.username=root
spring.datasource.password=password
spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver

# DBCP specific settings
spring.datasource.type=org.apache.commons.dbcp2.BasicDataSource
spring.datasource.dbcp2.initial-size=5
spring.datasource.dbcp2.max-total=20
spring.datasource.dbcp2.max-idle=10
spring.datasource.dbcp2.min-idle=5

2 C3P0

<dependency>
    <groupId>com.mchange</groupId>
    <artifactId>c3p0</artifactId>
    <version>0.9.5.5</version>
</dependency>

spring.datasource.url=jdbc:mysql://localhost:3306/mydb
spring.datasource.username=root
spring.datasource.password=password
spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver

# C3P0 specific settings
spring.datasource.type=com.mchange.v2.c3p0.ComboPooledDataSource
spring.datasource.c3p0.min-size=5
spring.datasource.c3p0.max-size=20
spring.datasource.c3p0.acquire-increment=1
spring.datasource.c3p0.idle-test-period=3000
spring.datasource.c3p0.max-statements=50
spring.datasource.c3p0.max-idle-time=600

3 Druid

<dependency>
    <groupId>com.alibaba</groupId>
    <artifactId>druid</artifactId>
    <version>1.2.8</version>
</dependency>

spring.datasource.url=jdbc:mysql://localhost:3306/mydb
spring.datasource.username=root
spring.datasource.password=password
spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver

# Druid specific settings
spring.datasource.type=com.alibaba.druid.pool.DruidDataSource
spring.datasource.druid.initial-size=5
spring.datasource.druid.min-idle=5
spring.datasource.druid.max-active=20
spring.datasource.druid.max-wait=60000
spring.datasource.druid.time-between-eviction-runs-millis=60000
spring.datasource.druid.min-evictable-idle-time-millis=300000
spring.datasource.druid.validation-query=SELECT 1
spring.datasource.druid.test-while-idle=true
spring.datasource.druid.test-on-borrow=false
spring.datasource.druid.test-on-return=false