tomcat源码分析（二）启动过程

在Catalina的load方法中，首先初始化Server组件。

  // Start the new server
        if (server instanceof Lifecycle) {
            try {
                server.initialize();
            } catch (LifecycleException e) {
                log.error("Catalina.start", e);
            }
        }

在StandardServer中初始化service

    public void initialize()
        throws LifecycleException
    {
        if (initialized) {
                log.info(sm.getString("standardServer.initialize.initialized"));
            return;
        }
        lifecycle.fireLifecycleEvent(INIT_EVENT, null);
        initialized = true;

        if( oname==null ) {
            try {
                oname=new ObjectName( "Catalina:type=Server");
                Registry.getRegistry(null, null)
                    .registerComponent(this, oname, null );
            } catch (Exception e) {
                log.error("Error registering ",e);
            }
        }

        // Register global String cache
        try {
            ObjectName oname2 =
                new ObjectName(oname.getDomain() + ":type=StringCache");
            Registry.getRegistry(null, null)
                .registerComponent(new StringCache(), oname2, null );
        } catch (Exception e) {
            log.error("Error registering ",e);
        }

        // Initialize our defined Services
        for (int i = 0; i < services.length; i++) {
            services[i].initialize();
        }
    }

在StandardService又初始化Connector

    public void initialize()
            throws LifecycleException
    {
        // Service shouldn‘t be used with embeded, so it doesn‘t matter
        if (initialized) {
            if(log.isInfoEnabled())
                log.info(sm.getString("standardService.initialize.initialized"));
            return;
        }
        initialized = true;

        if( oname==null ) {
            try {
                // Hack - Server should be deprecated...
                Container engine=this.getContainer();
                domain=engine.getName();
                oname=new ObjectName(domain + ":type=Service,serviceName="+name);
                this.controller=oname;
                Registry.getRegistry(null, null)
                    .registerComponent(this, oname, null);

                Executor[] executors = findExecutors();
                for (int i = 0; i < executors.length; i++) {
                    ObjectName executorObjectName =
                        new ObjectName(domain + ":type=Executor,name=" + executors[i].getName());
                    Registry.getRegistry(null, null)
                        .registerComponent(executors[i], executorObjectName, null);
                }

            } catch (Exception e) {
                log.error(sm.getString("standardService.register.failed",domain),e);
            }

        }
        if( server==null ) {
            // Register with the server
            // HACK: ServerFactory should be removed...

            ServerFactory.getServer().addService(this);
        }

        // Initialize our defined Connectors
        synchronized (connectors) {
                for (int i = 0; i < connectors.length; i++) {
                    connectors[i].initialize();
                }
        }
    }

我们从Connector的初始化方法开始看：

public void initialize()
        throws LifecycleException
    {
        if (initialized) {
            if(log.isInfoEnabled())
                log.info(sm.getString("coyoteConnector.alreadyInitialized"));
           return;
        }

        this.initialized = true;

        if( oname == null && (container instanceof StandardEngine)) {
            try {
                // we are loaded directly, via API - and no name was given to us
                StandardEngine cb=(StandardEngine)container;
                oname = createObjectName(cb.getName(), "Connector");
                Registry.getRegistry(null, null)
                    .registerComponent(this, oname, null);
                controller=oname;
            } catch (Exception e) {
                log.error( "Error registering connector ", e);
            }
            if(log.isDebugEnabled())
                log.debug("Creating name for connector " + oname);
        }

        // Initializa adapter
        adapter = new CoyoteAdapter(this);//创建一个适配器，该适配器会完成请求的真正处理
        protocolHandler.setAdapter(adapter);

        IntrospectionUtils.setProperty(protocolHandler, "jkHome",
                                       System.getProperty("catalina.base"));

        try {
            protocolHandler.init();//对于不同的协议，会有不同的ProtocolHandler实现类，我们来看Http11Protocol，它用来处理HTTP请求
        } catch (Exception e) {
            throw new LifecycleException
                (sm.getString
                 ("coyoteConnector.protocolHandlerInitializationFailed", e));
        }
    }

Http11Protocol的init()的核心代码

 public void init() throws Exception {
        endpoint.setName(getName());
        endpoint.setHandler(cHandler);
    ...
  try {
            endpoint.init();
        } catch (Exception ex) {
            log.error(sm.getString("http11protocol.endpoint.initerror"), ex);
            throw ex;
        }
}

endpoint的实现是JIoEndPoint

public void init()
        throws Exception {

        if (initialized)
            return;

        // Initialize thread count defaults for acceptor
    //默认处理线程数
        if (acceptorThreadCount == 0) {
            acceptorThreadCount = 1;
        }
    //得到服务端默认Socket即DefaultServerSocketFactory
        if (serverSocketFactory == null) {
            serverSocketFactory = ServerSocketFactory.getDefault();
        }
    //创建服务端Socket,为客户端请求做准备
        if (serverSocket == null) {
            try {
                if (address == null) {
                    serverSocket = serverSocketFactory.createSocket(port, backlog);
                } else {
                    serverSocket = serverSocketFactory.createSocket(port, backlog, address);
                }
            } catch (BindException be) {
                if (address == null)
                    throw new BindException(be.getMessage() + "<null>:" + port);
                else
                    throw new BindException(be.getMessage() + " " +
                            address.toString() + ":" + port);
            }
        }
        //if( serverTimeout >= 0 )
        //    serverSocket.setSoTimeout( serverTimeout );

        initialized = true;

    }

所有的加载工作已经完成了。接下来要启动这些组件了。