SpringBoot中Druid数据库连接池的配置：

（1）Druid的依赖和log4j的依赖

<!-- https://mvnrepository.com/artifact/com.alibaba/druid -->
<dependency>
    <groupId>com.alibaba</groupId>
    <artifactId>druid</artifactId>
    <version>1.1.21</version>
</dependency>


<!-- https://mvnrepository.com/artifact/log4j/log4j -->
<dependency>
    <groupId>log4j</groupId>
    <artifactId>log4j</artifactId>
    <version>1.2.17</version>
</dependency>

（2）yaml中的配置

spring:
  datasource:
    username: xxx
    password: xxx
    #?serverTimezone=UTC解决时区的报错
    url: jdbc:mysql://localhost:3306/数据库的名字?serverTimezone=UTC&useUnicode=true&characterEncoding=utf-8
    driver-class-name: com.mysql.cj.jdbc.Driver
    type: com.alibaba.druid.pool.DruidDataSource #这是使用的Druid连接池，所以需要安装Druid的依赖；

    #Spring Boot 默认是不注入这些属性值的，需要自己绑定
    #druid 数据源专有配置
    initialSize: 5
    minIdle: 5
    maxActive: 20
    maxWait: 60000
    timeBetweenEvictionRunsMillis: 60000
    minEvictableIdleTimeMillis: 300000
    validationQuery: SELECT 1 FROM DUAL
    testWhileIdle: true
    testOnBorrow: false
    testOnReturn: false
    poolPreparedStatements: true

    #配置监控统计拦截的filters，stat:监控统计、log4j：日志记录、wall：防御sql注入
    #如果允许时报错  java.lang.ClassNotFoundException: org.apache.log4j.Priority
    #则导入 log4j 依赖即可，Maven 地址：https://mvnrepository.com/artifact/log4j/log4j
    filters: stat,wall,log4j
    maxPoolPreparedStatementPerConnectionSize: 20
    useGlobalDataSourceStat: true
    connectionProperties: druid.stat.mergeSql=true;druid.stat.slowSqlMillis=500

#对于mabatis的配置
mybatis:
  type-aliases-package: com.example.pojo  #实体类所在包
  mapper-locations: classpath:mybatis/mapper/*.xml #指定mapper文件所在的包

（3）在config中配置Druid的配置文件：

package com.example.config;

import com.alibaba.druid.pool.DruidDataSource;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

import javax.sql.DataSource;

/**
 * @author Lenovo
 * @date 2023/4/12
 * @time 14:03
 * @project springboot_mybatis
 **/

@Configuration
public class DruidConfig {


    //自定义Druid数据源到spring容器中，不再让springboot自动创建

    /**
     * @ConfigurationProperties(prefix = "spring.datasource")：作用就是将 全局配置文件中
     * 前缀为 spring.datasource的属性值注入到 com.alibaba.druid.pool.DruidDataSource 的同名参数中
     */
    @ConfigurationProperties(prefix = "spring.datasource")

    //注册Bean对象：
    @Bean
    public DataSource druidDataSource(){
        //返回一个druidDataSource;
        return new DruidDataSource();
    }
}