Tomcat学习笔记(十三)
服务器组件和服务组件
服务器组件
org.apache.catalina.Server接口的实例表示Catalina的整个servlet引擎，包含了所有的组件。使用一种优雅的方法来启动/关闭整个系统，不需要再对连接器和容器分别启动/关闭。
关闭/启动的工作原理。当启动服务器组件时，他会启动其中所有的组件，然后它就一直等待关闭命令，如果要关闭系统，可以向指定端口发送一条关闭命令。服务器收到关闭命令后，就会关闭其中所有的组件。
看一下Server接口的几个方法。
public interface Server extends Lifecycle { public int getPort();//返回监听关闭的端口 public void setPort(int port);//设置关闭端口 public Catalina getCatalina();//返回catalina组件 public void addService(Service service);//添加服务 public Service findService(String name);//查询服务 public Service[] findServices();//查询所有服务 public void removeService(Service service);//移除服务 }
StandardServer类
StandardServer类是Server接口的标准实现。
一个服务器组件可以有0个或者多个服务组件。StandardServer类提供了addService()方法、removeService()方法和findService方法的实现。
addService将服务组件添加到服务器组件中，服务器组件中包含一个数组来保存服务组件。
public void addService(Service service) { service.setServer(this); synchronized (services) { Service results[] = new Service[services.length + 1]; System.arraycopy(services, 0, results, 0, services.length); results[services.length] = service; services = results; if (getState().isAvailable()) { //服务可用，就启动服务 try { service.start(); } catch (LifecycleException e) { // Ignore } } // Report this property change to interested listeners support.firePropertyChange("service", null, service); } }
removeService从服务组件数组中移除，并停止服务。
public void removeService(Service service) { synchronized (services) { int j = -1; for (int i = 0; i < services.length; i++) { if (service == services[i]) { j = i; break; } } if (j < 0) return; try { services[j].stop(); } catch (LifecycleException e) { // Ignore } int k = 0; Service results[] = new Service[services.length - 1]; for (int i = 0; i < services.length; i++) { if (i != j) results[k++] = services[i]; } services = results; // Report this property change to interested listeners support.firePropertyChange("service", service, null); } }
StandardServer类的4个生命周期相关的方法，是由LifecycleBase中的init调用initInternal(StandardServer),start调用startInternal（StandardServer）,stop调用stopInternal（StandardServer），await（StandardServer）方法。
initInternal主要是对资源的初始化和服务组件的初始化。
protected void initInternal() throws LifecycleException { super.initInternal(); ... // Register the naming resources globalNamingResources.init(); ... // Initialize our defined Services for (int i = 0; i < services.length; i++) { services[i].init(); } }
startInternal设置生命周期，设置服务器组件的状态，启动服务组件。
@Override protected void startInternal() throws LifecycleException { fireLifecycleEvent(CONFIGURE_START_EVENT, null); setState(LifecycleState.STARTING); globalNamingResources.start(); // Start our defined Services synchronized (services) { for (int i = 0; i < services.length; i++) { services[i].start(); } } }
await一直等待停止命令。
Service接口
主要与连接器，服务器组件，执行器相关的信息
public interface Service extends Lifecycle { public void addConnector(Connector connector); public Connector[] findConnectors(); public void removeConnector(Connector connector); public void addExecutor(Executor ex); public Executor[] findExecutors(); public Executor getExecutor(String name); public void removeExecutor(Executor ex); public Server getServer(); public void setServer(Server server); }
ServiceStandard对Service的接口实现，同时也有生命周期方法
startInternal
protected void startInternal() throws LifecycleException { if(log.isInfoEnabled()) log.info(sm.getString("standardService.start.name", this.name)); setState(LifecycleState.STARTING); // Start our defined Container first if (container != null) { synchronized (container) { container.start(); } } synchronized (executors) { for (Executor executor: executors) { executor.start(); } } // Start our defined Connectors second synchronized (connectors) { for (Connector connector: connectors) { try { // If it has already failed, don't try and start it if (connector.getState() != LifecycleState.FAILED) { connector.start(); } } catch (Exception e) { log.error(sm.getString( "standardService.connector.startFailed", connector), e); } } } }
initInternal初始化容器，执行器以及连接器。
protected void initInternal() throws LifecycleException { super.initInternal(); if (container != null) { container.init(); } // Initialize any Executors for (Executor executor : findExecutors()) { if (executor instanceof LifecycleMBeanBase) { ((LifecycleMBeanBase) executor).setDomain(getDomain()); } executor.init(); } // Initialize our defined Connectors synchronized (connectors) { for (Connector connector : connectors) { try { connector.init(); } catch (Exception e) { String message = sm.getString( "standardService.connector.initFailed", connector); log.error(message, e); if (Boolean.getBoolean("org.apache.catalina.startup.EXIT_ON_INIT_FAILURE")) throw new LifecycleException(message); } } } }
stopInternal停止连接器和执行器。
protected void stopInternal() throws LifecycleException { // Pause connectors first synchronized (connectors) { for (Connector connector: connectors) { try { connector.pause(); } catch (Exception e) { log.error(sm.getString( "standardService.connector.pauseFailed", connector), e); } } } if(log.isInfoEnabled()) log.info(sm.getString("standardService.stop.name", this.name)); setState(LifecycleState.STOPPING); // Stop our defined Container second if (container != null) { synchronized (container) { container.stop(); } } // Now stop the connectors synchronized (connectors) { for (Connector connector: connectors) { if (!LifecycleState.STARTED.equals( connector.getState())) { // Connectors only need stopping if they are currently // started. They may have failed to start or may have been // stopped (e.g. via a JMX call) continue; } try { connector.stop(); } catch (Exception e) { log.error(sm.getString( "standardService.connector.stopFailed", connector), e); } } } synchronized (executors) { for (Executor executor: executors) { executor.stop(); } } }
