一、概述

查看Jetty-io包，清单如下：

接口类：
ByteBufferPool
ClientConnectionFactory
Connection
Connection.Listener
Connection.UpgradeFrom
Connection.UpgradeTo
EndPoint
ManagedSelector.SelectableEndPoint
NetworkTrafficListener
实体类：
AbstractConnection
AbstractEndPoint
ArrayByteBufferPool
ArrayByteBufferPool.Bucket
ByteArrayEndPoint
ByteBufferPool.Lease
ChannelEndPoint
ClientConnectionFactory.Helper
Connection.Listener.Adapter
FillInterest
IdleTimeout
LeakTrackingByteBufferPool
ManagedSelector
MappedByteBufferPool
MappedByteBufferPool.Tagged
NegotiatingClientConnection
NegotiatingClientConnectionFactory
NetworkTrafficListener.Adapter
NetworkTrafficSelectChannelEndPoint
SelectChannelEndPoint
SelectorManager
WriteFlusher
WriterOutputStream
异常类：
EofException
RuntimeIOException

从名字看几个主要的类可能为：Connection、ByteBufferPool、SelectorManager、EndPoint，因为其他类应该是从中延伸出来的。

二、类分析

首先看Connection接口：

public interface Connection extends Closeable
{public void addListener(Listener listener);public void onOpen();/*** <p>Callback method invoked when this {@link Connection} is closed.</p>* <p>Creators of the connection implementation are responsible for calling this method.</p>*/public void onClose();/*** @return the {@link EndPoint} associated with this {@link Connection}*/public EndPoint getEndPoint();/*** <p>Performs a logical close of this connection.</p>* <p>For simple connections, this may just mean to delegate the close to the associated* {@link EndPoint} but, for example, SSL connections should write the SSL close message* before closing the associated {@link EndPoint}.</p>*/@Overridepublic void close();public int getMessagesIn();public int getMessagesOut();public long getBytesIn();public long getBytesOut();public long getCreatedTimeStamp();public interface UpgradeFrom extends Connection{/* ------------------------------------------------------------ *//** Take the input buffer from the connection on upgrade.* <p>This method is used to take any unconsumed input from* a connection during an upgrade.* @return A buffer of unconsumed input. The caller must return the buffer* to the bufferpool when consumed and this connection must not.*/ByteBuffer onUpgradeFrom();}public interface UpgradeTo extends Connection{/*** <p>Callback method invoked when this {@link Connection} is upgraded.</p>* <p>This must be called before {@link #onOpen()}.</p>* @param prefilled An optional buffer that can contain prefilled data. Typically this* results from an upgrade of one protocol to the other where the old connection has buffered* data destined for the new connection.  The new connection must take ownership of the buffer* and is responsible for returning it to the buffer pool*/void onUpgradeTo(ByteBuffer prefilled);}/* ------------------------------------------------------------ *//** * <p>A Listener for connection events.</p>* <p>Listeners can be added to a {@link Connection} to get open and close events.* The AbstractConnectionFactory implements a pattern where objects implement* this interface that have been added via {@link Container#addBean(Object)} to* the Connector or ConnectionFactory are added as listeners to all new connections* </p>*/public interface Listener{public void onOpened(Connection connection);public void onClosed(Connection connection);public static class Adapter implements Listener{@Overridepublic void onOpened(Connection connection){}@Overridepublic void onClosed(Connection connection){}}}
}

Connection接口主要用来添加监听，并定义监听接口Listener。

再看一个实现了Connection接口的抽象类AbstractConnection：

public abstract class AbstractConnection implements Connection
{private static final Logger LOG = Log.getLogger(AbstractConnection.class);private final List<Listener> listeners = new CopyOnWriteArrayList<>();private final long _created=System.currentTimeMillis();private final EndPoint _endPoint;private final Executor _executor;private final Callback _readCallback;private int _inputBufferSize=2048;protected AbstractConnection(EndPoint endp, Executor executor){if (executor == null)throw new IllegalArgumentException("Executor must not be null!");_endPoint = endp;_executor = executor;_readCallback = new ReadCallback();}@Overridepublic void addListener(Listener listener){listeners.add(listener);}public int getInputBufferSize(){return _inputBufferSize;}public void setInputBufferSize(int inputBufferSize){_inputBufferSize = inputBufferSize;}protected Executor getExecutor(){return _executor;}@Deprecatedpublic boolean isDispatchIO(){return false;}protected void failedCallback(final Callback callback, final Throwable x){if (callback.isNonBlocking()){try{callback.failed(x);}catch (Exception e){LOG.warn(e);}}else{try{getExecutor().execute(new Runnable(){@Overridepublic void run(){try{callback.failed(x);}catch (Exception e){LOG.warn(e);}}});}catch(RejectedExecutionException e){LOG.debug(e);callback.failed(x);}}}/*** <p>Utility method to be called to register read interest.</p>* <p>After a call to this method, {@link #onFillable()} or {@link #onFillInterestedFailed(Throwable)}* will be called back as appropriate.</p>* @see #onFillable()*/public void fillInterested(){if (LOG.isDebugEnabled())LOG.debug("fillInterested {}",this);getEndPoint().fillInterested(_readCallback);}public boolean isFillInterested(){return getEndPoint().isFillInterested();}/*** <p>Callback method invoked when the endpoint is ready to be read.</p>* @see #fillInterested()*/public abstract void onFillable();/*** <p>Callback method invoked when the endpoint failed to be ready to be read.</p>* @param cause the exception that caused the failure*/protected void onFillInterestedFailed(Throwable cause){if (LOG.isDebugEnabled())LOG.debug("{} onFillInterestedFailed {}", this, cause);if (_endPoint.isOpen()){boolean close = true;if (cause instanceof TimeoutException)close = onReadTimeout();if (close){if (_endPoint.isOutputShutdown())_endPoint.close();else{_endPoint.shutdownOutput();fillInterested();}}}}/*** <p>Callback method invoked when the endpoint failed to be ready to be read after a timeout</p>* @return true to signal that the endpoint must be closed, false to keep the endpoint open*/protected boolean onReadTimeout(){return true;}@Overridepublic void onOpen(){if (LOG.isDebugEnabled())LOG.debug("onOpen {}", this);for (Listener listener : listeners)listener.onOpened(this);}@Overridepublic void onClose(){if (LOG.isDebugEnabled())LOG.debug("onClose {}",this);for (Listener listener : listeners)listener.onClosed(this);}@Overridepublic EndPoint getEndPoint(){return _endPoint;}@Overridepublic void close(){getEndPoint().close();}@Overridepublic int getMessagesIn(){return -1;}@Overridepublic int getMessagesOut(){return -1;}@Overridepublic long getBytesIn(){return -1;}@Overridepublic long getBytesOut(){return -1;}@Overridepublic long getCreatedTimeStamp(){return _created;}@Overridepublic String toString(){return String.format("%s@%x[%s]",getClass().getSimpleName(),hashCode(),_endPoint);}private class ReadCallback implements Callback{@Overridepublic void succeeded(){onFillable();}@Overridepublic void failed(final Throwable x){onFillInterestedFailed(x);}@Overridepublic String toString(){return String.format("AC.ReadCB@%x{%s}", AbstractConnection.this.hashCode(),AbstractConnection.this);}}
}