tomcat 七 源码分析-5 server初始化中的JMX(DynamicMBean)

tomcat 7 源码分析-5 server初始化中的JMX(DynamicMBean)
tomcat 7 源码分析-5 server初始化中的JMX(DynamicMBean)

protected void initInternal() throws LifecycleException { super.initInternal(); // Register global String cache // Note although the cache is global, if there are multiple Servers // present in the JVM (may happen when embedding) then the same cache // will be registered under multiple names onameStringCache = register(new StringCache(), "type=StringCache"); // Register the MBeanFactory onameMBeanFactory = register(new MBeanFactory(), "type=MBeanFactory"); // Register the naming resources onameNamingResoucres = register(globalNamingResources, "type=NamingResources"); // Initialize our defined Services for (int i = 0; i < services.length; i++) { services[i].init(); } }

?先看super.initInternal();


protected void initInternal() throws LifecycleException { // If oname is not null then registration has already happened via // preRegister(). if (oname == null) { mserver = Registry.getRegistry(null, null).getMBeanServer(); oname = register(this, getObjectNameKeyProperties()); } }

?看来问题的关键就在register这个函数了。


protected final ObjectName register(Object obj, String objectNameKeyProperties) { // Construct an object name with the right domain StringBuilder name = new StringBuilder(getDomain()); name.append(':'); name.append(objectNameKeyProperties); ObjectName on = null; try { on = new ObjectName(name.toString()); Registry.getRegistry(null, null).registerComponent(obj, on, null); } catch (MalformedObjectNameException e) { log.warn(sm.getString("lifecycleMBeanBase.registerFail", obj, name), e); } catch (Exception e) { log.warn(sm.getString("lifecycleMBeanBase.registerFail", obj, name), e); } return on; }

?接下去看registerComponent函数


public void registerComponent(Object bean, ObjectName oname, String type) throws Exception { if( log.isDebugEnabled() ) { log.debug( "Managed= "+ oname); } if( bean ==null ) { log.error("Null component " + oname ); return; } try { if( type==null ) { type=bean.getClass().getName(); } ManagedBean managed = findManagedBean(bean.getClass(), type); // The real mbean is created and registered DynamicMBean mbean = managed.createMBean(bean); if( getMBeanServer().isRegistered( oname )) { if( log.isDebugEnabled()) { log.debug("Unregistering existing component " + oname ); } getMBeanServer().unregisterMBean( oname ); } getMBeanServer().registerMBean( mbean, oname); } catch( Exception ex) { log.error("Error registering " + oname, ex ); throw ex; } }

?终于知道这一段代码要完成什么功能了，原来register就是将参数中的object注册到MBeanServer中去，而且使用的是DynamicMBean。

Tomcat中

BaseModelMBean实现了DynamicMBean接口，是真正意思上的动态Mbeans。

ManagedBean是对MBeans的管理，例如生产Mbean等。

Registry是又一层次的封装，是将Object(Mbeans)注册到MBeanServer的一个接口，同时还提供对已有Mbeans的查找，防止重复注册等。

说到这里，如果不了解MBean的话，肯定不知道在说什么。所以我下一个续，先从简单的Standard MBeans说起。