Configuring Druid DataSource Monitoring and Filters in Spring Boot

Druid is a Java database connection pool developed by Alibaba, offering powerful monitoring and extensibility features that surpass other pools such as HikariCP, C3P0, and DBCP. It provides built‑in filters like StatFilter for statistics, WallFilter for SQL injection protection, and log4j2 for logging.

1. Adding Dependencies

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

<dependency>
  <groupId>mysql</groupId>
  <artifactId>mysql-connector-java</artifactId>
  <scope>runtime</scope>
</dependency>

<dependency>
  <groupId>org.springframework.boot</groupId>
  <artifactId>spring-boot-starter-log4j2</artifactId>
</dependency>

<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>

2. Configuring Druid Properties

The application.yml file can be used to set datasource credentials, driver class, URL, and Druid‑specific pool settings such as initial-size , minIdle , max-active , and validation queries. Filters are enabled via the filters property (e.g., stat,wall,log4j2 ), and the WebStatFilter is configured to monitor web requests.

spring:
  datasource:
    druid:
      # JDBC basic configuration
      username: xxx
      password: xxx
      driver-class-name: com.mysql.cj.jdbc.Driver
      url: jdbc:mysql://127.0.0.1:3306/test?serverTimezone=Asia/Shanghai
      platform: mysql
      type: com.alibaba.druid.pool.DruidDataSource

      # Connection pool configuration
      initial-size: 5
      minIdle: 10
      max-active: 20
      max-wait: 60000
      min-evictable-idle-time-millis: 600000
      max-evictable-idle-time-millis: 900000
      validationQuery: select 1
      testWhileIdle: true
      testOnBorrow: false
      poolPreparedStatements: true
      maxOpenPreparedStatements: 20
      keepAlive: true
      aop-patterns: "com.springboot.template.dao.*"

      # Enable built‑in filters
      filters: stat,wall,log4j2

      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
        deny: ""

3. Enabling SQL Monitoring and Slow‑SQL Logging

By setting log-slow-sql: true and slow-sql-millis: 2000 in the stat filter configuration, Druid records any SQL that exceeds two seconds, outputting it to the log.

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

4. Spring AOP Monitoring

Adding the spring-boot-starter-aop dependency and configuring spring.datasource.druid.aop-patterns enables method‑level monitoring of DAO calls.

spring.datasource.druid.aop-patterns="com.springboot.template.dao.*"

5. Removing the Default Alibaba Advertisement

The Druid UI includes a footer advertisement injected by common.js . It can be removed either by editing the JAR‑packed common.js (commenting out // this.buildFooter(); ) or by registering a custom servlet filter that rewrites the JavaScript response.

@Configuration
@ConditionalOnWebApplication
public class RemoveDruidAdConfig {
    @Bean
    public FilterRegistrationBean removeDruidAdFilterRegistrationBean(DruidStatProperties properties) {
        DruidStatProperties.StatViewServlet config = properties.getStatViewServlet();
        String pattern = config.getUrlPattern() != null ? config.getUrlPattern() : "/druid/*";
        String commonJsPattern = pattern.replaceAll("\\*", "js/common.js");
        Filter filter = new Filter() {
            @Override public void init(FilterConfig filterConfig) throws ServletException {}
            @Override public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
                chain.doFilter(request, response);
                response.resetBuffer();
                String text = Utils.readFromResource("support/http/resources/js/common.js");
                text = text.replaceAll("\n", "");
                text = text.replaceAll("powered.*?shrek.wang", "");
                response.getWriter().write(text);
            }
            @Override public void destroy() {}
        };
        FilterRegistrationBean registrationBean = new FilterRegistrationBean();
        registrationBean.setFilter(filter);
        registrationBean.addUrlPatterns(commonJsPattern);
        return registrationBean;
    }
}

6. Accessing Druid Monitoring Data Programmatically

After enabling StatFilter , the DruidStatManagerFacade API can retrieve datasource statistics, e.g., via DruidStatManagerFacade#getDataSourceStatDataList() . A simple REST controller can expose this data as JSON.

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

The document concludes with a promotional section unrelated to the technical content.