弱小和无知不是生存的障碍，傲慢才是
**

spring:
  datasource:
    url: jdbc:mysql://127.0.0.1:3306/java58
    username: root
    password: admin
    driver-class-name: com.mysql.cj.jdbc.Driver
    type: com.alibaba.druid.pool.DruidDataSource
    #  数据源其他配置
    initialSize: 5
    minIdle: 5
    maxActive: 20
    maxWait: 60000
    timeBetweenEvictionRunsMillis: 60000
    minEvictableIdleTimeMillis: 300000
    validaionQuery: SELECT 1 FROM DUAL
    testWhileIdle: true
    testOnBorrow: false
    testOnReturn: false
    poolPreparedStatements: true
    #    配置监控统计拦截的filters 去掉后监控界面sql无法统计，‘wall’用于防火墙
    filters: stat,wall,log4j
    maxPoolPreparedStatementPerConnectionSize: 20
    useGlobalDataSourceStat: true
    connectionProperties: druid.stat.mergeSql=true,druid.stat.slowSqlMills=500
server:
  port: 8080

从initialSize开始往后的在DataSourceProperties中并无属性，所以这些数据默认是不起作用的，

是加载不到druid数据源中

所以编写配置类

新版本似乎解决了（未验证）

import com.alibaba.druid.pool.DruidDataSource;
import com.alibaba.druid.support.http.StatViewServlet;
import com.alibaba.druid.support.http.WebStatFilter;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.boot.web.servlet.FilterRegistrationBean;
import org.springframework.boot.web.servlet.ServletRegistrationBean;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import java.util.HashMap;
import java.util.Map;
@Configuration
public class DruidConfig {
  @Bean
  @ConfigurationProperties(prefix = "spring.datasource")
  public DataSource druid() {
    return new DruidDataSource();
  }
//配置servlet filter
  @Bean
  public ServletRegistrationBean myServlet() {
    ServletRegistrationBean bean = new ServletRegistrationBean(new StatViewServlet(), "/druid/*");
    Map<String, String> initParams = new HashMap<>();
    initParams.put("loginUsername", "admin");
    initParams.put("loginPassword", "123456");
    initParams.put("allow", "");// 如果不写就是默认允许所有
    initParams.put("deny", "127.0.0.1");
    //是否能够重置数据.
    bean.addInitParameter("resetEnable", "false");
    bean.setInitParameters(initParams);
    return bean;
  }
  @Bean
  public FilterRegistrationBean myFilter() {
    FilterRegistrationBean bean = new FilterRegistrationBean();
    bean.setFilter(new WebStatFilter());
    Map<String, String> initParams = new HashMap<>();
    initParams.put("exclusions", "*.js,*.css,/druid/*");
    bean.setInitParameters(initParams);
    bean.addUrlPatterns("/*");
    return bean;
  }
}

浏览器访问：http://localhost:8080/druid/login.html