Comprehensive Guide to Configuring Druid DataSource in Spring Boot

1. Basic Concepts

Druid is a Java‑based database connection pool praised for its powerful monitoring and extensibility; while HikariCP may be slightly faster, Druid offers richer features such as StatFilter, WallFilter, and log4j2 integration.

2. Adding Dependencies

<!-- Alibaba Druid datasource -->
<dependency>
    <groupId>com.alibaba</groupId>
    <artifactId>druid-spring-boot-starter</artifactId>
    <version>1.1.23</version>
</dependency>

<!-- MySQL 8 driver -->
<dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
    <scope>runtime</scope>
</dependency>

<!-- Log4j2 for logging -->
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-log4j2</artifactId>
</dependency>

<!-- MyBatis starter, excluding default HikariCP -->
<dependency>
    <groupId>org.mybatis.spring.boot</groupId>
    <artifactId>mybatis-spring-boot-starter</artifactId>
    <version>2.1.3</version>
    <exclusions>
        <exclusion>
            <groupId>com.zaxxer</groupId>
            <artifactId>HikariCP</artifactId>
        </exclusion>
    </exclusions>
</dependency>

3. Configuration Properties

Configure the Druid datasource in application.yml , setting JDBC basics, pool sizes, validation query, test flags, prepared‑statement caching, and enabling built‑in filters ( stat,wall,log4j2 ).

spring:
  datasource:
    druid:
      initial-size: 5
      minIdle: 10
      max-active: 20
      max-wait: 60000
      time-between-eviction-runs-millis: 2000
      min-evictable-idle-time-millis: 600000
      max-evictable-idle-time-millis: 900000
      validationQuery: select 1
      testWhileIdle: true
      testOnBorrow: false
      testOnReturn: false
      poolPreparedStatements: true
      maxOpenPreparedStatements: 20
      keepAlive: true
      aop-patterns: "com.springboot.template.dao.*"
      filters: stat,wall,log4j2
      filter:
        stat:
          enabled: true
          db-type: mysql
          log-slow-sql: true
          slow-sql-millis: 2000
        slf4j:
          enabled: true
      web-stat-filter:
        enabled: true
        url-pattern: "/*"
        exclusions: "*.js,*.gif,*.jpg,*.png,*.css,*.ico,/druid/*"
        session-stat-enable: true
        session-stat-max-count: 1000
      stat-view-servlet:
        enabled: true
        url-pattern: /druid/*
        reset-enable: false
        login-username: root
        login-password: 123
        allow: 127.0.0.1

4. Monitoring Pages

After starting the application, access /druid/login.html to view the built‑in monitoring UI, which includes DataSource basic info, SQL statistics, URL statistics, Spring AOP monitoring, SQL firewall, session details, and a JSON API.

5. SQL Monitoring & Slow‑Query Logging

Enable WebStatFilter to collect request‑level SQL data and configure StatFilter to log slow queries (default threshold 2 seconds).

spring:
  datasource:
    druid:
      web-stat-filter:
        enabled: true
        url-pattern: "/*"
        exclusions: "*.js,*.gif,*.jpg,*.png,*.css,*.ico,/druid/*"
        session-stat-enable: true
        session-stat-max-count: 1000

      filter:
        stat:
          enabled: true
          db-type: mysql
          log-slow-sql: true
          slow-sql-millis: 2000

6. Removing Druid’s Footer Advertisement

Two approaches are provided: (1) manually comment out the this.buildFooter(); line in the JAR’s common.js ; (2) register a custom servlet filter that rewrites the resource, stripping the ad HTML.

@Configuration
@ConditionalOnWebApplication
@AutoConfigureAfter(DruidDataSourceAutoConfigure.class)
@ConditionalOnProperty(name = "spring.datasource.druid.stat-view-servlet.enabled", havingValue = "true", matchIfMissing = true)
public class RemoveDruidAdConfig {
    @Bean
    public FilterRegistrationBean removeDruidAdFilterRegistrationBean(DruidStatProperties properties) {
        // ... create filter that reads common.js, removes ad snippets, writes back ...
    }
}

7. Programmatic Access to Monitoring Data

Use DruidStatManagerFacade (e.g., getDataSourceStatDataList() ) or expose a custom @RestController to return the statistics as JSON.

@RestController
@RequestMapping("/druid")
public class DruidStatController {
    @GetMapping("/stat")
    public Object druidStat() {
        return DruidStatManagerFacade.getInstance().getDataSourceStatDataList();
    }
}