关于 druid 监控的两个小问题

前一段时间做一个小需求，需要展示 druid 的监控页面，我们都知道 druid 监控地址是：http://ip:port/druid/index.html，但是当时一直报 404，后来查了资料，引入的 jar 包：

<dependency>
  <groupId>com.alibaba</groupId>
  <artifactId>druid</artifactId>
  <version>1.2.24</version>
</dependency>

应该是因为不是通过 starter 包引入的，所以需要手动配置：

package cn.bridgeli.demo;

import com.alibaba.druid.support.jakarta.StatViewServlet;
import com.alibaba.druid.support.jakarta.WebStatFilter;
import com.alibaba.druid.util.Utils;
import jakarta.servlet.Filter;
import jakarta.servlet.FilterChain;
import jakarta.servlet.ServletException;
import jakarta.servlet.ServletRequest;
import jakarta.servlet.ServletResponse;
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.io.IOException;

@Configuration
public class DruidConfig {

  @Bean
  public ServletRegistrationBean<StatViewServlet> statViewServlet() {
    ServletRegistrationBean<StatViewServlet> servletRegistrationBean = new ServletRegistrationBean<>(new StatViewServlet(), "/druid/*");
    // 设置登录用户名和密码
    servletRegistrationBean.addInitParameter("loginUsername", "BridgeLi");
    servletRegistrationBean.addInitParameter("loginPassword", "BridgeLi");
    return servletRegistrationBean;
  }

  @Bean
  public FilterRegistrationBean<WebStatFilter> webStatFilter() {
    FilterRegistrationBean<WebStatFilter> filterRegistrationBean = new FilterRegistrationBean<>(new WebStatFilter());
    filterRegistrationBean.addUrlPatterns("/*");
    filterRegistrationBean.addInitParameter("exclusions", "*.js,*.gif,*.jpg,*.png,*.css,*.ico,/druid/*");
    return filterRegistrationBean;
  }
}

另外一个小问题就是，这么引入之后，打开监控页最下面会有 alibaba 的广告，一般情况下，我们肯定是想去掉的，广告代码所在的位置在 support/http/resources/js/common.js 这个 js 里面，网上有人说直接解压删掉，重新打包就行了，但是这个有问题就是必须用重新打包的这个 jar，搜了一下资料，其实去掉也很简单，在上面的那个类里面增加一个 配置过滤掉即可：

@Bean
public FilterRegistrationBean<Filter> removeDruidAdFilterRegistrationBean() {
  // 获取web监控页面的参数
  // 提取common.js的配置路径
  String pattern = "/druid/*";
  String commonJsPattern = pattern.replaceAll("\\*", "js/common.js");
  final String filePath = "support/http/resources/js/common.js";
  // 创建filter进行过滤
  Filter filter = new Filter() {
    @Override
    public void init(jakarta.servlet.FilterConfig filterConfig) throws ServletException {
    }

    @Override
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
      chain.doFilter(request, response);
      // 重置缓冲区，响应头不会被重置
      response.resetBuffer();
      // 获取common.js
      String text = Utils.readFromResource(filePath);
      // 正则替换banner, 除去底部的广告信息
      text = text.replaceAll("<a.*?banner\"></a><br/>", "");
      text = text.replaceAll("powered.*?shrek.wang</a>", "");
      response.getWriter().write(text);
    }

    @Override
    public void destroy() {
    }
  };
  FilterRegistrationBean<Filter> registrationBean = new FilterRegistrationBean<>();
  registrationBean.setFilter(filter);
  registrationBean.addUrlPatterns(commonJsPattern);
  return registrationBean;
}

如果是引入的 starter 也可以把方法的声明改成下面这种：

@SuppressWarnings({"rawtypes", "unchecked"})
@Bean
@ConditionalOnProperty(name = "spring.datasource.druid.statViewServlet.enabled", havingValue = "true")
public FilterRegistrationBean removeDruidFilterRegistrationBean(DruidStatProperties properties) {
  // 获取web监控页面的参数
  DruidStatProperties.StatViewServlet config = properties.getStatViewServlet();
  // 提取common.js的配置路径
  String pattern = config.getUrlPattern() != null ? config.getUrlPattern() : "/druid/*";
  String commonJsPattern = pattern.replaceAll("\\*", "js/common.js");
  final String filePath = "support/http/resources/js/common.js";
  // 创建filter进行过滤
  Filter filter = new Filter() {
    @Override
    public void init(javax.servlet.FilterConfig filterConfig) throws ServletException {
    }

    @Override
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
      chain.doFilter(request, response);
      // 重置缓冲区，响应头不会被重置
      response.resetBuffer();
      // 获取common.js
      String text = Utils.readFromResource(filePath);
      // 正则替换banner, 除去底部的广告信息
      text = text.replaceAll("<a.*?banner\"></a><br/>", "");
      text = text.replaceAll("powered.*?shrek.wang</a>", "");
      response.getWriter().write(text);
    }

    @Override
    public void destroy() {
    }
  };
  FilterRegistrationBean<Filter> registrationBean = new FilterRegistrationBean<>();
  registrationBean.setFilter(filter);
  registrationBean.addUrlPatterns(commonJsPattern);
  return registrationBean;
}

其实就是怎么拿到 common.js 而已。