如何输出TOMCAT的配置参数

有时候我们想获取当前运行的Tomcat的各种参数，比如maxThreads、acceptThreadCount等。例如下面两张图：
#####1、Http11Protocol

#####1、Http11NioProtocol

#####3、实现代码

import com.google.common.collect.Maps;
import org.junit.Test;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import javax.management.MBeanServer;
import javax.management.MBeanServerFactory;
import javax.management.ObjectName;
import java.util.List;
import java.util.Map;


/**
 * Created by wangxindong on 2017/10/31.
 */
public class TomcatContainerMonitor {
    private static final Logger logger = LoggerFactory.getLogger(TomcatContainerMonitor.class);
    private static final String tomcatEmbedDomain = "Tomcat";
    private static final String tomcatDomain = "Catalina";

    private static final String bioProtocol="org.apache.coyote.http11.Http11Protocol";
    private static final String nioProtocol="org.apache.coyote.http11.Http11NioProtocol";

    public  Object doMonitor() {
        Map<String, Object> map = Maps.newHashMap();

        List<MBeanServer> mBeanServers = MBeanServerFactory.findMBeanServer(null);
        if (!mBeanServers.isEmpty()) {
            MBeanServer mBeanServer = mBeanServers.get(0);
            String domain = getTomcatDomian(mBeanServer);
            try {
                ObjectName[] objNames = (ObjectName[]) mBeanServer.getAttribute(new ObjectName(domain, "type", "Service"), "connectorNames");
                for (ObjectName on : objNames) {
                    Map<String, Object> connector = Maps.newHashMap();
                    Object protocol = mBeanServer.getAttribute(on, "protocol");
                    connector.put("protocol", protocol);
                    Object acceptCount = mBeanServer.getAttribute(on, "acceptCount");
                    connector.put("acceptCount", acceptCount);

                    Object connectionTimeout = mBeanServer.getAttribute(on, "connectionTimeout");
                    connector.put("connectionTimeout", connectionTimeout);

                    Object protocolHandlerClassName = mBeanServer.getAttribute(on, "protocolHandlerClassName");
                    connector.put("protocolHandlerClassName", protocolHandlerClassName);

                    Object enableLookups = mBeanServer.getAttribute(on, "enableLookups");
                    connector.put("enableLookups", enableLookups);

                    Object uriEncoding = mBeanServer.getAttribute(on, "URIEncoding");
                    connector.put("URIEncoding", uriEncoding);

                    Object useBodyEncodingForURI = mBeanServer.getAttribute(on, "useBodyEncodingForURI");
                    connector.put("useBodyEncodingForURI", useBodyEncodingForURI);

                    Object localPort = mBeanServer.getAttribute(on, "port");
                    map.put("connector-" + localPort, connector);

                    if (protocolHandlerClassName.toString().equals(nioProtocol)) {//NIO
                        String threadPoolONStr = domain + ":type=ThreadPool,name=\"http-nio-" + localPort + "\"";
                        ObjectName threadPoolON = new ObjectName(threadPoolONStr);
                        Map<String, Object> threadPoolMap = Maps.newHashMap();

                        Object maxConnections = mBeanServer.getAttribute(threadPoolON, "maxConnections");
                        threadPoolMap.put("maxConnections", maxConnections);

                        Object maxThreads = mBeanServer.getAttribute(threadPoolON, "maxThreads");
                        threadPoolMap.put("maxThreads", maxThreads);

                        Object minSpareThreads = mBeanServer.getAttribute(threadPoolON, "minSpareThreads");
                        threadPoolMap.put("minSpareThreads", minSpareThreads);

                        Object acceptorThreadCount = mBeanServer.getAttribute(threadPoolON, "acceptorThreadCount");
                        threadPoolMap.put("acceptorThreadCount", acceptorThreadCount);

                        Object pollerThreadCount = mBeanServer.getAttribute(threadPoolON, "pollerThreadCount");
                        threadPoolMap.put("pollerThreadCount", pollerThreadCount);

                        Object pollerThreadPriority = mBeanServer.getAttribute(threadPoolON, "pollerThreadPriority");
                        threadPoolMap.put("pollerThreadPriority", pollerThreadPriority);

                        connector.put("threadPool", threadPoolMap);
                    }else if(protocolHandlerClassName.toString().equals(bioProtocol)){
                        String threadPoolONStr = domain + ":type=ThreadPool,name=\"http-bio-" + localPort + "\"";
                        ObjectName threadPoolON = new ObjectName(threadPoolONStr);
                        Map<String, Object> threadPoolMap = Maps.newHashMap();

                        Object maxConnections = mBeanServer.getAttribute(threadPoolON, "maxConnections");
                        threadPoolMap.put("maxConnections", maxConnections);

                        Object maxThreads = mBeanServer.getAttribute(threadPoolON, "maxThreads");
                        threadPoolMap.put("maxThreads", maxThreads);

                        Object minSpareThreads = mBeanServer.getAttribute(threadPoolON, "minSpareThreads");
                        threadPoolMap.put("minSpareThreads", minSpareThreads);

                        Object acceptorThreadCount = mBeanServer.getAttribute(threadPoolON, "acceptorThreadCount");
                        threadPoolMap.put("acceptorThreadCount", acceptorThreadCount);

                        connector.put("threadPool", threadPoolMap);
                    }

                }
            } catch (Exception e) {
                logger.warn("获取信息失败", e);
            }
        }
        return map;
    }

    private  String getTomcatDomian(MBeanServer mBeanServer) {
        try {
            mBeanServer.getAttribute(new ObjectName(tomcatEmbedDomain, "type", "Service"), "connectorNames");
            return tomcatEmbedDomain;
        } catch (Exception e) {
            return tomcatDomain;
        }
    }

    @Test
    public void test(){
        TomcatContainerMonitor wcm = new TomcatContainerMonitor();
        wcm.doMonitor();
    }

}

获取MAP对象通过json序列化输出到页面，如上面两张图。
#####4、需要依赖

  com.alibaba
  fastjson
  1.2.39
  


  com.google.collections
  google-collections
  1.0
  


  org.slf4j
  slf4j-api
  1.7.20
  

#####5、原理总结

public abstract class LifecycleMBeanBase extends LifecycleBase
        implements MBeanRegistration {}

Tomcat对server.xml文件解析，解析出来的组件和容器都继承了LifecycleMBeanBase类，其父类LifecycleBase实现了容器的生命周期管理，其接口MBeanRegistration由Java JMX（Java Management Extensions）框架提供，用于监听JMX注册事件；LifecycleMBeanBase的子类都遵循JMX标准，通过getObjectNameKeyProperties()抽象方法定义类的注册名称，并在每个对象初始化（执行生命周期init方法）时注册到MBeanServer中，MBeanServer给出了外部管理系统访问JMX框架的接口，因此外部系统或工具可以实时监控到MBean的各种数据信息。这就是我们能够通过MBeanServer获取到Tomcat各种配置信息的原理。

参考资料：
http://www.fanyilun.me/2016/10/10/Tomcat的启动分析/