tomcat 代码集

Tomcat类是整个tomcat的起点，负责加载所有的配置信息以及把配置信息解析转换成tomcat组件对象。

Context addWebapp(String contextPath, String baseDir) throws ServletException //添加context（这个可以理解为默认context）
Context addContext(String contextPath, String baseDir) //添加context （这个是真正的上层业务逻辑的context）
Wrapper addServlet(String contextPath, String servletName,String servletClass)
public void start() throws LifecycleException { //Server和Connector的加载
    getServer();
    getConnector();
    server.start();
}

public Host getHost() { //随着context的加载而加载
    if (host == null) {
        host = new StandardHost();
        host.setName(hostname);

        getEngine().addChild( host );
    }
    return host;
}

public Engine getEngine() {
    if(engine == null ) {
        getServer();
        engine = new StandardEngine();
        engine.setRealm(defaultRealm);
        service.setContainer(engine);
    }
    return engine;
}

从接口上看：一个Server中包含了多个Service，一个Service中包含多个Connector以及一个Engine，一个Engine中包含多个Host，一个Host下有多个Context，一个Context下有多个Wrapper。

但是从实现上可以看到一个tomcat其实内部只包含了一个Server，一个Server包含了一个Service，一个Service包含了一个Connector

interface Server extends Lifecycle{
	public void addService(Service service);
}

public interface Service extends Lifecycle {
	public void addConnector(Connector connector);
	public void setContainer(Container container);
}
public class StandardService extends LifecycleMBeanBase implements Service {
	protected Connector connectors[] = new Connector[0];
	protected Container container = null;
}

连接器

class Connector extends LifecycleMBeanBase{
protected ProtocolHandler protocolHandler = null;
public Request createRequest() {
    Request request = new Request();
    request.setConnector(this);
    return (request);
}
public Response createResponse() {
    Response response = new Response();
    response.setConnector(this);
    return (response);
}
@Override
protected void initInternal() throws LifecycleException {

    super.initInternal();

    // Initialize adapter
    adapter = new CoyoteAdapter(this);
    protocolHandler.setAdapter(adapter);

    try {
        protocolHandler.init();
    } catch (Exception e) {
        throw new LifecycleException
            (sm.getString
             ("coyoteConnector.protocolHandlerInitializationFailed"), e);
    }
}
protected void startInternal() throws LifecycleException {
	protocolHandler.start();
}
}
 
public interface ProtocolHandler {//协议托管
	public void setAdapter(Adapter adapter);
	public Adapter getAdapter();
	其他组件生命周期的方法 start、init等等
}

AbstractEndpoint：整个tomcat I/O流的处理框架，内部实现了tomcat底层通讯的所需要的一些基本组件。

public abstract class AbstractEndpoint {
private volatile LimitLatch connectionLimitLatch = null;
public static interface Handler {
	public Object getGlobal();
	public void recycle();
}
public abstract static class Acceptor implements Runnable {
}
}

1.LimitLatch：用于限制tomcat并发数，当一个请求进来之后，只有等到了LimitLatch才能进行下一步的处理，否则只能等待

2.Aceptor：用于接受socket，并对socket进行封装

3.Handler：用于处理Aceptor处理后的Socket

public abstract class AbstractProtocol implements ProtocolHandler, MBeanRegistration {
	protected AbstractEndpoint endpoint = null;
	protected static class RecycledProcessors<P extends Processor<S>, S> extends ConcurrentLinkedQueue<Processor<S>>{
		private transient AbstractConnectionHandler<S,P> handler;
		public Processor<S> poll()
		public boolean offer(Processor<S> processor)
	}
	protected abstract static class AbstractConnectionHandler<S,P extends Processor<S> implements AbstractEndpoint.Handler{
		protected RecycledProcessors<P,S> recycledProcessors = new RecycledProcessors<P,S>(this);
		public SocketState process(SocketWrapper<S> socket, SocketStatus status) {
			...
			state = processor.process(socket);
		}
		protected abstract P createProcessor();
	}
}
 
public abstract class AbstractHttp11Protocol extends AbstractProtocol
public abstract class AbstractHttp11JsseProtocol extends AbstractHttp11Protocol
public class Http11NioProtocol extends AbstractHttp11JsseProtocol {
	public Http11NioProtocol() {
  		  endpoint=new NioEndpoint();
  	 	  cHandler = new Http11ConnectionHandler(this);
  	 	  ((NioEndpoint) endpoint).setHandler(cHandler);
	}

	protected static class Http11ConnectionHandler extends AbstractConnectionHandler<NioChannel,Http11NioProcessor> implements Handler {
		public Http11NioProcessor createProcessor() {
    		Http11NioProcessor processor = new Http11NioProcessor(proto.getMaxHttpHeaderSize(), (NioEndpoint)proto.endpoint,proto.getMaxTrailerSize());
            ...
		    register(processor);
    		return processor;
		}
	}
}
public class NioEndpoint extends AbstractEndpoint {
	protected class Acceptor extends AbstractEndpoint.Acceptor {
		public void run(){
			try {
				countUpOrAwaitConnection();
				socket = serverSock.accept();
			} catch (IOException ioe) {
					...
			}
			if (running && !paused) {
		    if (!setSocketOptions(socket)) {
        		countDownConnection();
		        closeSocket(socket);
		    }
		}
		protected boolean setSocketOptions(SocketChannel socket) {
 		   // Process the connection
  		  try {
	        socket.configureBlocking(false);
    	    Socket sock = socket.socket();
        	socketProperties.setProperties(sock);

	        NioChannel channel = nioChannels.poll();
    	    if ( channel == null ) {
        	    // SSL setup
            	if (sslContext != null) {
      			 …
                channel = new SecureNioChannel(socket, engine, bufhandler, selectorPool);
            } else {
                …
                channel = new NioChannel(socket, bufhandler);
            }
	        } else {
 	        	   channel.setIOChannel(socket);
 			}
				 getPoller0().register(channel);
			}
		}
	}
 
	public class Poller implements Runnable {
 	   public void run() {
   	     Iterator<SelectionKey> iterator =
  	              keyCount > 0 ? selector.selectedKeys().iterator() : null;
   	     while (iterator != null && iterator.hasNext()) {
    	        SelectionKey sk = iterator.next();
     	       KeyAttachment attachment = (KeyAttachment) sk.attachment();
      	      // Attachment may be null if another thread has called
      	      // cancelledKey()
      	      if (attachment == null) {
        	        iterator.remove();
         	   } else {
          	      attachment.access();
          	      iterator.remove();
          	      processKey(sk, attachment);
            }
        }
    }

   	 protected boolean processKey(SelectionKey sk, KeyAttachment attachment) {
    	    if (!processSocket(channel, SocketStatus.OPEN, true)){
    	        processSocket(channel, SocketStatus.DISCONNECT, true);
    	    }
   	 }

   	 	public boolean processSocket(NioChannel socket, SocketStatus status, boolean dispatch) {
    	    SocketProcessor sc = processorCache.poll();
    	    if ( sc == null ) sc = new SocketProcessor(socket,status);
    	    else sc.reset(socket,status);
     	   if ( dispatch && getExecutor()!=null ) getExecutor().execute(sc);
     	   else sc.run();
   	 	}
	}

	protected class SocketProcessor implements Runnable {
 	   public void run() {
  	      if (status == null) {
   	         state = handler.process(
     	               (KeyAttachment) key.attachment(),
   	                 SocketStatus.OPEN);
     	   } else {
     	       state = handler.process(
        	            (KeyAttachment) key.attachment(),
        	            status);
       		 }
   		 }
	}
}

Processor：协议处理器，把socket处理成request和response。

public interface Processor<S> {
	SocketState process(SocketWrapper<S> socketWrapper) throws IOException;
}
public abstract class AbstractProcessor<S> implements ActionHook, Processor<S> {
	protected Adapter adapter;
	protected AbstractEndpoint endpoint;
	public abstract SocketState process(SocketWrapper<S> socket)
}
 
public abstract class AbstractHttp11Processor<S> extends AbstractProcessor<S> {
	Request request ;
	Response response ;
	public SocketState process(SocketWrapper<S> socketWrapper){
		setSocketWrapper(socketWrapper);
		prepareRequest(); //加一些Http的参数给request
		adapter.service(request, response);
	}
}
public class Http11NioProcessor extends AbstractHttp11Processor<NioChannel> {
}

Adaptor用于真正处理请求，也就是把Request和Response传递给上层的Web应用Container

public interface Adapter { //连接了底层的processor和上层的container
	public void service(Request req, Response res)
}
public class CoyoteAdapter implements Adapter {
	public void service(org.apache.coyote.Request req, org.apache.coyote.Response res){
		Request request = (Request) req.getNote(ADAPTER_NOTES); //ServletRequest
		Response response = (Response) res.getNote(ADAPTER_NOTES);//ServletResponse
		boolean postParseSuccess = postParseRequest(req, request, res, response);
		connector.getService().getContainer().getPipeline().getFirst().invoke(request, response); //进入容器
	}
 
	protected boolean postParseRequest(org.apache.coyote.Request req,
                                   Request request,
                                   org.apache.coyote.Response res,
                                   Response response){
		//cookie、session、requestLine等等Http组件
		connector.getMapper().map(serverName, decodedURI, version,
                          request.getMappingData()); //设置本次请求的host、context、wrapper
		request.setContext((Context) request.getMappingData().context);
		request.setWrapper((Wrapper) request.getMappingData().wrapper);
		parseSessionCookiesId(req, request);
		parseSessionSslId(request);
	}
}
 
public final class Mapper {
	protected Host[] hosts = new Host[0];
	protected static final class Host extends MapElement {
	    public ContextList contextList = null;
	}
	protected static final class ContextList {
    	public Context[] contexts = new Context[0];
	}
	public synchronized void addHost(String name, String[] aliases,Object host)
	public void addContextVersion(String hostName, Object host, String path,String version, Object context, String[] welcomeResources,javax.naming.Context resources)
	public void map(MessageBytes host, MessageBytes uri, String version, MappingData mappingData)
}
public class MapperListener extends LifecycleMBeanBase{
	private Mapper mapper = null;
	@Override
	public void startInternal() throws LifecycleException {
	    setState(LifecycleState.STARTING);
	    Engine engine = (Engine) connector.getService().getContainer();
    	addListeners(engine);
	    Container[] conHosts = engine.findChildren();
    	for (Container conHost : conHosts) {
        Host host = (Host) conHost;
        if (!LifecycleState.NEW.equals(host.getState())) {
            registerHost(host);
        }
    }
	}
	private void registerHost(Host host) {
   	 mapper.addHost(host.getName(), aliases, host);
   	 for (Container container : host.findChildren()) {
   	     if (container.getState().isAvailable()) {
   	         registerContext((Context) container);
   	     }
  	  }
	}
 
	private void registerContext(Context context) {
   	 for (Container container : context.findChildren()) {
   	     registerWrapper((Wrapper) container);
    	}
	}
}

生命周期接口：

public interface Lifecycle {
	LifeCycle所有需要的时间状态：BEFORE_INIT_EVENT、AFTER_INIT_EVENT、START_EVENT等等
	public void init() throws LifecycleException;
	public void start() throws LifecycleException;
	public void stop() throws LifecycleException;
	public void destroy() throws LifecycleException;
}
 
public abstract class LifecycleBase implements Lifecycle {
	private LifecycleSupport lifecycle = new LifecycleSupport(this);
	public final synchronized void init() throws LifecycleException {
  		  if (!state.equals(LifecycleState.NEW)) {
   		     invalidTransition(Lifecycle.BEFORE_INIT_EVENT);
   		 }
   	 	setStateInternal(LifecycleState.INITIALIZING, null, false);

   		 try {
     	   initInternal();
  		  } catch (Throwable t) {
      	  ExceptionUtils.handleThrowable(t);
        	setStateInternal(LifecycleState.FAILED, null, false);
	        throw new LifecycleException(
    	            sm.getString("lifecycleBase.initFail",toString()), t);
	    }

    	setStateInternal(LifecycleState.INITIALIZED, null, false);
	}
	protected abstract void initInternal() throws LifecycleException;
	protected abstract void stopInternal() throws LifecycleException;
	...
}
 
public final class LifecycleSupport {
	private LifecycleListener listeners[] = new LifecycleListener[0];
	public void addLifecycleListener(LifecycleListener listener)
	public void fireLifecycleEvent(String type, Object data) {

    LifecycleEvent event = new LifecycleEvent(lifecycle, type, data);
    LifecycleListener interested[] = listeners;
    for (int i = 0; i < interested.length; i++)
        interested[i].lifecycleEvent(event);

	}
}
 
public abstract class LifecycleMBeanBase extends LifecycleBase implements MBeanRegistration

容器的接口：

public interface Container extends Lifecycle {
 	public void addChild(Container child);
	public Pipeline getPipeline();
	public void backgroundProcess();
	public void addContainerListener(ContainerListener listener);
}
 
public abstract class ContainerBase extends LifecycleMBeanBase{
	protected Pipeline pipeline = new StandardPipeline(this);
	@Override
	public void backgroundProcess() {

           cluster.backgroundProcess();

            loader.backgroundProcess();

            manager.backgroundProcess();
            realm.backgroundProcess();
        Valve current = pipeline.getFirst();
   		 while (current != null) {
        		try {
       	     current.backgroundProcess();
     	   } catch (Exception e) {
      	      log.warn(sm.getString("containerBase.backgroundProcess.valve", current), e);
      	  }
       	 current = current.getNext();
   		 }
   		 fireLifecycleEvent(Lifecycle.PERIODIC_EVENT, null);
	}
	public void invoke(Request request, Response response)
    	throws IOException, ServletException {
	    pipeline.getFirst().invoke(request, response);
	}
 
	protected class ContainerBackgroundProcessor implements Runnable {
   		 public void run() {
     		Thread.sleep(backgroundProcessorDelay * 1000L);
      	  	processChildren(parent, cl);
    	}
    	protected void processChildren(Container container, ClassLoader cl) {
        	container.backgroundProcess();
        	Container[] children = container.findChildren();
        	for (int i = 0; i < children.length; i++) {
         	   if (children[i].getBackgroundProcessorDelay() <= 0) {
           	     processChildren(children[i], cl);
            }
        }
    }
}

Container的默认实现为ContainerBase，然后对应的四个子类为StandardEngine、StandardHost、StandardContext、StandardWrapper。

public interface Pipeline {
	public void addValve(Valve valve);
	public Valve[] getValves();
}
class StandardPipeline extends LifecycleBase implements Pipeline, Contained{
	protected Valve first = null;
	protected Valve basic = null;
}
public interface Valve  {
	public Valve getNext();
	public void backgroundProcess();
	public void invoke(Request request, Response response)
}

public abstract class ValveBase extends LifecycleMBeanBase
    implements Contained, Valve {
	protected Container container = null;
	public abstract void invoke(Request request, Response response)throws IOException, ServletException;
}

阀门控制整个请求的流向，Valve则是真正对请求进行处理，Container存储了所需要的所有原始信息

public interface Wrapper extends Container {
	public Servlet allocate() throws ServletException;
	public void load() throws ServletException;
}
class StandardWrapper extends ContainerBase implements ServletConfig, Wrapper{
	protected volatile Servlet instance = null;
	protected InstanceSupport instanceSupport = new InstanceSupport(this);
}
final class StandardWrapperValve extends ValveBase {
	public final void invoke(Request request, Response response){
		if (!unavailable) {
	 	   servlet = wrapper.allocate();
		}
		ApplicationFilterChain filterChain = factory.createFilterChain(request, wrapper, servlet);
		...
		filterChain.doFilter(request.getRequest(), response.getResponse());
}
 
public final class ApplicationFilterFactory {
	public ApplicationFilterChain createFilterChain(ServletRequest request, Wrapper wrapper, Servlet servlet){
		filterChain = (ApplicationFilterChain) req.getFilterChain();
		filterChain.setServlet(servlet);
		filterChain.setSupport(((StandardWrapper)wrapper).getInstanceSupport());
	}
}
 
public final class InstanceSupport {
    private Wrapper wrapper = null;
    private InstanceListener listeners[] = new InstanceListener[0];
    public void fireInstanceEvent(String type, Filter filter,
                                  ServletRequest request,
                                  ServletResponse response) {

        InstanceEvent event = new InstanceEvent(wrapper, filter, type,
                request, response);
        InstanceListener interested[] = listeners;
        for (int i = 0; i < interested.length; i++)
            interested[i].instanceEvent(event);
    }
}