public void invoke(Request request, Response response) // SimpleContainer.invokethrows IOException, ServletException {String servletName = ( (HttpServletRequest) request).getRequestURI();servletName = servletName.substring(servletName.lastIndexOf("/") + 1);URLClassLoader loader = null;try { // 创建类加载器URL[] urls = new URL[1];URLStreamHandler streamHandler = null;File classPath = new File(WEB_ROOT);String repository = (new URL("file", null, classPath.getCanonicalPath() + File.separator)).toString() ;urls[0] = new URL(null, repository, streamHandler);loader = new URLClassLoader(urls);}catch (IOException e) {System.out.println(e.toString() );}Class myClass = null;try {myClass = loader.loadClass("servlet." + servletName);}catch (ClassNotFoundException e) {System.out.println(e.toString());}Servlet servlet = null;try {servlet = (Servlet) myClass.newInstance(); // 创建请求URI对应的servlet实例 servlet.service((HttpServletRequest) request, (HttpServletResponse) response);}......}

I'm as helpless as a kitten up a tree.
那么实际上应该发送如下内容：
1D\r\n
I'm as helpless as a kitten u
9\r\n
p a tree.
0\r\n
1D 的10进制表示是29， 表明第一个块的长度是29个字节，\0\r\n 表明事务已经完成；

Expect: 100-continue  //客户端发送

HTTP/1.1 100 continue
//注意，返回内容后面要加上 CRLF 字符。然后server 继续读取输入流的内容。

public final class HttpConnectorimplements Connector, Lifecycle, Runnable {

public final class Bootstrap {public static void main(String[] args) {HttpConnector connector = new HttpConnector();SimpleContainer container = new SimpleContainer();connector.setContainer(container);try {connector.initialize();connector.start();// make the application wait until we press any key.System.in.read();}catch (Exception e) {e.printStackTrace();}}
}

 public void initialize() // <span style="font-family: 宋体; font-size: 16px;  line-height: 24px;"><strong>HttpConnector.initialize()</strong></span>throws LifecycleException {if (initialized)throw new LifecycleException (sm.getString("httpConnector.alreadyInitialized"));this.initialized=true;Exception eRethrow = null;// Establish a server socket on the specified porttry {serverSocket = open();} catch (IOException ioe) {log("httpConnector, io problem: ", ioe);eRethrow = ioe;} catch (KeyStoreException kse) {log("httpConnector, keystore problem: ", kse);eRethrow = kse;} catch (NoSuchAlgorithmException nsae) {log("httpConnector, keystore algorithm problem: ", nsae);eRethrow = nsae;} catch (CertificateException ce) {log("httpConnector, certificate problem: ", ce);eRethrow = ce;} catch (UnrecoverableKeyException uke) {log("httpConnector, unrecoverable key: ", uke);eRethrow = uke;} catch (KeyManagementException kme) {log("httpConnector, key management problem: ", kme);eRethrow = kme;}if ( eRethrow != null )throw new LifecycleException(threadName + ".open", eRethrow);}

 private ServerSocket open() // HttpConnector.open()throws IOException, KeyStoreException, NoSuchAlgorithmException,CertificateException, UnrecoverableKeyException,KeyManagementException{// Acquire the server socket factory for this ConnectorServerSocketFactory factory = getFactory();// If no address is specified, open a connection on all addressesif (address == null) {log(sm.getString("httpConnector.allAddresses"));try {return (factory.createSocket(port, acceptCount));} catch (BindException be) {throw new BindException(be.getMessage() + ":" + port);}}// Open a server socket on the specified addresstry {InetAddress is = InetAddress.getByName(address);log(sm.getString("httpConnector.anAddress", address));try {return (factory.createSocket(port, acceptCount, is));} catch (BindException be) {throw new BindException(be.getMessage() + ":" + address +":" + port);}} catch (Exception e) {log(sm.getString("httpConnector.noAddress", address));try {return (factory.createSocket(port, acceptCount));} catch (BindException be) {throw new BindException(be.getMessage() + ":" + port);}}}

 private Stack processors = new Stack(); // HttpConnector.java

    void recycle(HttpProcessor processor) { // HttpConnector.java//        if (debug >= 2)//            log("recycle: Recycling processor " + processor);processors.push(processor);}

private HttpProcessor createProcessor() {synchronized (processors) {if (processors.size() > 0) {// if (debug >= 2)// log("createProcessor: Reusing existing processor");return ((HttpProcessor) processors.pop()); // attend for this line.}if ((maxProcessors > 0) && (curProcessors < maxProcessors)) {// if (debug >= 2)// log("createProcessor: Creating new processor");return (newProcessor());} else {if (maxProcessors < 0) {// if (debug >= 2)// log("createProcessor: Creating new processor");return (newProcessor());} else {// if (debug >= 2)// log("createProcessor: Cannot create new processor");return (null);}}}}

     public void start() throws LifecycleException { // HttpConnector.start()// Validate and update our current stateif (started)throw new LifecycleException(sm.getString("httpConnector.alreadyStarted"));threadName = "HttpConnector[" + port + "]";lifecycle.fireLifecycleEvent(START_EVENT, null);started = true;// Start our background threadthreadStart(); // invoke run method.// Create the specified minimum number of processorswhile (curProcessors < minProcessors) {if ((maxProcessors > 0) && (curProcessors >= maxProcessors))break;HttpProcessor processor = newProcessor();recycle(processor);}}

      private HttpProcessor newProcessor() { // H<span style="font-family: 宋体;">ttpConnector.newProcessor()</span>//        if (debug >= 2)//            log("newProcessor: Creating new processor");HttpProcessor processor = new HttpProcessor(this, curProcessors++);if (processor instanceof Lifecycle) {try {((Lifecycle) processor).start();} catch (LifecycleException e) {log("newProcessor", e);return (null);}}created.addElement(processor);  // created is a Vector Collection.return (processor);} 

     private Vector created = new Vector();

 void recycle(HttpProcessor processor) { // HttpContainer.recycle()//        if (debug >= 2)//            log("recycle: Recycling processor " + processor);processors.push(processor);}

 public void stop() throws LifecycleException {// Validate and update our current stateif (!started)throw new LifecycleException(sm.getString("httpConnector.notStarted"));lifecycle.fireLifecycleEvent(STOP_EVENT, null);started = false;// Gracefully shut down all processors we have createdfor (int i = created.size() - 1; i >= 0; i--) {HttpProcessor processor = (HttpProcessor) created.elementAt(i); // this line.if (processor instanceof Lifecycle) {try {((Lifecycle) processor).stop();} catch (LifecycleException e) {log("HttpConnector.stop", e);}}}synchronized (threadSync) {// Close the server socket we were usingif (serverSocket != null) {try {serverSocket.close();} catch (IOException e) {;}}// Stop our background threadthreadStop();}serverSocket = null;}

public void run() { // HttpConnector.run()// Loop until we receive a shutdown commandwhile (!stopped) {// Accept the next incoming connection from the server socketSocket socket = null;try {//                if (debug >= 3)//                    log("run: Waiting on serverSocket.accept()");socket = serverSocket.accept();//                if (debug >= 3)//                    log("run: Returned from serverSocket.accept()");if (connectionTimeout > 0)socket.setSoTimeout(connectionTimeout);socket.setTcpNoDelay(tcpNoDelay);} catch (AccessControlException ace) {log("socket accept security exception", ace);continue;} catch (IOException e) {//                if (debug >= 3)//                    log("run: Accept returned IOException", e);try {// If reopening fails, exitsynchronized (threadSync) {if (started && !stopped)log("accept error: ", e);if (!stopped) {//                    if (debug >= 3)//                        log("run: Closing server socket");serverSocket.close();//                        if (debug >= 3)//                            log("run: Reopening server socket");serverSocket = open();}}//                    if (debug >= 3)//                        log("run: IOException processing completed");} catch (IOException ioe) {log("socket reopen, io problem: ", ioe);break;} catch (KeyStoreException kse) {log("socket reopen, keystore problem: ", kse);break;} catch (NoSuchAlgorithmException nsae) {log("socket reopen, keystore algorithm problem: ", nsae);break;} catch (CertificateException ce) {log("socket reopen, certificate problem: ", ce);break;} catch (UnrecoverableKeyException uke) {log("socket reopen, unrecoverable key: ", uke);break;} catch (KeyManagementException kme) {log("socket reopen, key management problem: ", kme);break;}continue;}// Hand this socket off to an appropriate processorHttpProcessor processor = createProcessor();if (processor == null) {try {log(sm.getString("httpConnector.noProcessor"));socket.close();} catch (IOException e) {;}continue;}//            if (debug >= 3)//                log("run: Assigning socket to processor " + processor);processor.assign(socket);// The processor will recycle itself when it finishes}// Notify the threadStop() method that we have shut ourselves down//        if (debug >= 3)//            log("run: Notifying threadStop() that we have shut down");synchronized (threadSync) {threadSync.notifyAll();}}

HttpProcessor processor = createProcessor(); // invoked by HttpContainer.run() method.
private Stack processors = new Stack(); // you should know the processors is a Stack.

     private HttpProcessor createProcessor() { // HttpConnector.createProcessor() synchronized (processors) {if (processors.size() > 0) {// if (debug >= 2)// log("createProcessor: Reusing existing processor");return ((HttpProcessor) processors.pop());}if ((maxProcessors > 0) && (curProcessors < maxProcessors)) {// if (debug >= 2)// log("createProcessor: Creating new processor");return (newProcessor());} else {if (maxProcessors < 0) {// if (debug >= 2)// log("createProcessor: Creating new processor");return (newProcessor());} else {// if (debug >= 2)// log("createProcessor: Cannot create new processor");return (null);}}}}<span style="font-family: 宋体;"> </span>

 // Hand this socket off to an appropriate processorHttpProcessor processor = createProcessor(); // these code are located in HttpConnector.run() if (processor == null) {try {log(sm.getString("httpConnector.noProcessor"));socket.close();} catch (IOException e) {;}continue;}//            if (debug >= 3)//                log("run: Assigning socket to processor " + processor);processor.assign(socket); // this line, invoked by HttpConnector.run method.// The processor will recycle itself when it finishes}// Notify the threadStop() method that we have shut ourselves down//        if (debug >= 3)//            log("run: Notifying threadStop() that we have shut down");synchronized (threadSync) {threadSync.notifyAll();}

 synchronized void assign(Socket socket) {// Wait for the Processor to get the previous Socketwhile (available) {try {wait();} catch (InterruptedException e) {}}// Store the newly available Socket and notify our threadthis.socket = socket;available = true;notifyAll();if ((debug >= 1) && (socket != null))log(" An incoming request is being assigned");}

private void process(Socket socket) {boolean ok = true;boolean finishResponse = true;SocketInputStream input = null;OutputStream output = null;// Construct and initialize the objects we will needtry {input = new SocketInputStream(socket.getInputStream(),connector.getBufferSize());} catch (Exception e) {log("process.create", e);ok = false;}keepAlive = true;while (!stopped && ok && keepAlive) {finishResponse = true;try {request.setStream(input);request.setResponse(response);output = socket.getOutputStream();response.setStream(output);response.setRequest(request);((HttpServletResponse) response.getResponse()).setHeader("Server", SERVER_INFO);} catch (Exception e) {log("process.create", e);ok = false;}// Parse the incoming requesttry {if (ok) {parseConnection(socket);parseRequest(input, output);if (!request.getRequest().getProtocol().startsWith("HTTP/0"))parseHeaders(input);if (http11) {// Sending a request acknowledge back to the client if// requested.ackRequest(output);// If the protocol is HTTP/1.1, chunking is allowed.if (connector.isChunkingAllowed())response.setAllowChunking(true);}}} catch (EOFException e) {// It's very likely to be a socket disconnect on either the // client or the serverok = false;finishResponse = false;} catch (ServletException e) {ok = false;try {((HttpServletResponse) response.getResponse()).sendError(HttpServletResponse.SC_BAD_REQUEST);} catch (Exception f) {;}} catch (InterruptedIOException e) {if (debug > 1) {try {log("process.parse", e);((HttpServletResponse) response.getResponse()).sendError(HttpServletResponse.SC_BAD_REQUEST);} catch (Exception f) {;}}ok = false;} catch (Exception e) {try {log("process.parse", e);((HttpServletResponse) response.getResponse()).sendError(HttpServletResponse.SC_BAD_REQUEST);} catch (Exception f) {;}ok = false;}// Ask our Container to process this requesttry {((HttpServletResponse) response).setHeader("Date", FastHttpDateFormat.getCurrentDate());if (ok) {connector.getContainer().invoke(request, response); // process method invokes the invoke method of corresponding servlet container}} catch (ServletException e) {log("process.invoke", e);try {((HttpServletResponse) response.getResponse()).sendError(HttpServletResponse.SC_INTERNAL_SERVER_ERROR);} catch (Exception f) {;}ok = false;} catch (InterruptedIOException e) {ok = false;} catch (Throwable e) {log("process.invoke", e);try {((HttpServletResponse) response.getResponse()).sendError(HttpServletResponse.SC_INTERNAL_SERVER_ERROR);} catch (Exception f) {;}ok = false;}// Finish up the handling of the requestif (finishResponse) {try {response.finishResponse();} catch (IOException e) {ok = false;} catch (Throwable e) {log("process.invoke", e);ok = false;}try {request.finishRequest();} catch (IOException e) {ok = false;} catch (Throwable e) {log("process.invoke", e);ok = false;}try {if (output != null)output.flush();} catch (IOException e) {ok = false;}}// We have to check if the connection closure has been requested// by the application or the response stream (in case of HTTP/1.0// and keep-alive).if ( "close".equals(response.getHeader("Connection")) ) {keepAlive = false;}// End of request processingstatus = Constants.PROCESSOR_IDLE;// Recycling the request and the response objectsrequest.recycle();response.recycle();}try {shutdownInput(input);socket.close();} catch (IOException e) {;} catch (Throwable e) {log("process.invoke", e);}socket = null;}

     public void run() { // HttpProcessor.run()// Process requests until we receive a shutdown signalwhile (!stopped) {// Wait for the next socket to be assignedSocket socket = await(); // this line, <span style="font-family: 宋体; font-size: 16px; line-height: 24px;">run方法的while循环执行到 await方法时会阻塞</span>if (socket == null)continue;// Process the request from this sockettry {process(socket);} catch (Throwable t) {log("process.invoke", t);}// Finish up this requestconnector.recycle(this);}// Tell threadStop() we have shut ourselves down successfullysynchronized (threadSync) {threadSync.notifyAll();}}

private synchronized Socket await() { // HttpProcessor.await()// Wait for the Connector to provide a new Socketwhile (!available) {try {wait();} catch (InterruptedException e) {}}// Notify the Connector that we have received this SocketSocket socket = this.socket;available = false;notifyAll();if ((debug >= 1) && (socket != null))log("  The incoming request has been awaited");return (socket);}

private void process(Socket socket) { // HttpProcessor.process()boolean ok = true;boolean finishResponse = true;SocketInputStream input = null;OutputStream output = null;// Construct and initialize the objects we will needtry {input = new SocketInputStream(socket.getInputStream(),connector.getBufferSize());} catch (Exception e) {log("process.create", e);ok = false;}keepAlive = true;while (!stopped && ok && keepAlive) {finishResponse = true;try {request.setStream(input);request.setResponse(response);output = socket.getOutputStream();response.setStream(output);response.setRequest(request);((HttpServletResponse) response.getResponse()).setHeader("Server", SERVER_INFO);} catch (Exception e) {log("process.create", e);ok = false;}// Parse the incoming requesttry {if (ok) {parseConnection(socket); // step1：解析连接parseRequest(input, output); // step2：解析请求if (!request.getRequest().getProtocol() .startsWith("HTTP/0"))parseHeaders(input); // step3：解析请求头if (http11) {// Sending a request acknowledge back to the client if// requested.ackRequest(output);// If the protocol is HTTP/1.1, chunking is allowed.if (connector.isChunkingAllowed())response.setAllowChunking(true);}}} catch (EOFException e) {// It's very likely to be a socket disconnect on either the // client or the serverok = false;finishResponse = false;} catch (ServletException e) {ok = false;try {((HttpServletResponse) response.getResponse()).sendError(HttpServletResponse.SC_BAD_REQUEST);} catch (Exception f) {;}} catch (InterruptedIOException e) {if (debug > 1) {try {log("process.parse", e);((HttpServletResponse) response.getResponse()).sendError(HttpServletResponse.SC_BAD_REQUEST);} catch (Exception f) {;}}ok = false;} catch (Exception e) {try {log("process.parse", e);((HttpServletResponse) response.getResponse()).sendError(HttpServletResponse.SC_BAD_REQUEST);} catch (Exception f) {;}ok = false;}// Ask our Container to process this requesttry {((HttpServletResponse) response).setHeader("Date", FastHttpDateFormat.getCurrentDate());if (ok) {connector.getContainer().invoke(request, response);}} catch (ServletException e) {log("process.invoke", e);try {((HttpServletResponse) response.getResponse()).sendError(HttpServletResponse.SC_INTERNAL_SERVER_ERROR);} catch (Exception f) {;}ok = false;} catch (InterruptedIOException e) {ok = false;} catch (Throwable e) {log("process.invoke", e);try {((HttpServletResponse) response.getResponse()).sendError(HttpServletResponse.SC_INTERNAL_SERVER_ERROR);} catch (Exception f) {;}ok = false;}// Finish up the handling of the requestif (finishResponse) {try {response.finishResponse();} catch (IOException e) {ok = false;} catch (Throwable e) {log("process.invoke", e);ok = false;}try {request.finishRequest();} catch (IOException e) {ok = false;} catch (Throwable e) {log("process.invoke", e);ok = false;}try {if (output != null)output.flush();} catch (IOException e) {ok = false;}}// We have to check if the connection closure has been requested// by the application or the response stream (in case of HTTP/1.0// and keep-alive).if ( "close".equals(response.getHeader("Connection")) ) {keepAlive = false;}// End of request processingstatus = Constants.PROCESSOR_IDLE;// Recycling the request and the response objectsrequest.recycle();response.recycle();}try {shutdownInput(input);socket.close();} catch (IOException e) {;} catch (Throwable e) {log("process.invoke", e);}socket = null;}

// Parse the incoming requesttry {  // there code are located in HttpProcessor.process() method.if (ok) {parseConnection(socket);parseRequest(input, output);if (!request.getRequest().getProtocol().startsWith("HTTP/0"))parseHeaders(input);if (http11) {// Sending a request acknowledge back to the client if// requested.ackRequest(output);// If the protocol is HTTP/1.1, chunking is allowed.if (connector.isChunkingAllowed())response.setAllowChunking(true);}}} 

private void parseConnection(Socket socket) // HttpProcessor.parseConnection()throws IOException, ServletException {if (debug >= 2)log("  parseConnection: address=" + socket.getInetAddress() +", port=" + connector.getPort());((HttpRequestImpl) request).setInet(socket.getInetAddress());if (proxyPort != 0)request.setServerPort(proxyPort);elserequest.setServerPort(serverPort);request.setSocket(socket);}

final class DefaultHeaders {// -------------------------------------------------------------- Constantsstatic final char[] AUTHORIZATION_NAME = "authorization".toCharArray();static final char[] ACCEPT_LANGUAGE_NAME = "accept-language".toCharArray();static final char[] COOKIE_NAME = "cookie".toCharArray();static final char[] CONTENT_LENGTH_NAME = "content-length".toCharArray();static final char[] CONTENT_TYPE_NAME = "content-type".toCharArray();static final char[] HOST_NAME = "host".toCharArray();static final char[] CONNECTION_NAME = "connection".toCharArray();static final char[] CONNECTION_CLOSE_VALUE = "close".toCharArray();static final char[] EXPECT_NAME = "expect".toCharArray();static final char[] EXPECT_100_VALUE = "100-continue".toCharArray();static final char[] TRANSFER_ENCODING_NAME ="transfer-encoding".toCharArray();static final HttpHeader CONNECTION_CLOSE =new HttpHeader("connection", "close");static final HttpHeader EXPECT_CONTINUE =new HttpHeader("expect", "100-continue");static final HttpHeader TRANSFER_ENCODING_CHUNKED =new HttpHeader("transfer-encoding", "chunked");

 private void parseHeaders(SocketInputStream input) // HttpProcessor.parseHeaders()throws IOException, ServletException {while (true) {HttpHeader header = request.allocateHeader();// Read the next headerinput.readHeader(header);if (header.nameEnd == 0) {if (header.valueEnd == 0) {return;} else {throw new ServletException(sm.getString("httpProcessor.parseHeaders.colon"));}}String value = new String(header.value, 0, header.valueEnd);if (debug >= 1)log(" Header " + new String(header.name, 0, header.nameEnd)+ " = " + value);......request.nextHeader();}}

if (header.nameEnd == 0) {if (header.valueEnd == 0) {return;} else {throw new ServletException(sm.getString("httpProcessor.parseHeaders.colon"));}}

public class SimpleContainer implements Container { // just demonstrate a core method invoke.public void invoke(Request request, Response response)throws IOException, ServletException {String servletName = ( (HttpServletRequest) request).getRequestURI();servletName = servletName.substring(servletName.lastIndexOf("/") + 1);URLClassLoader loader = null;try {URL[] urls = new URL[1];URLStreamHandler streamHandler = null;File classPath = new File(WEB_ROOT);String repository = (new URL("file", null, classPath.getCanonicalPath() + File.separator)).toString() ;urls[0] = new URL(null, repository, streamHandler);loader = new URLClassLoader(urls);}catch (IOException e) {System.out.println(e.toString() );}Class myClass = null;try {myClass = loader.loadClass("servlet." + servletName);}catch (ClassNotFoundException e) {System.out.println(e.toString());}Servlet servlet = null;try {servlet = (Servlet) myClass.newInstance();servlet.service((HttpServletRequest) request, (HttpServletResponse) response);}catch (Exception e) {System.out.println(e.toString());}catch (Throwable e) {System.out.println(e.toString());}}

 /*** Await a newly assigned Socket from our Connector, or <code>null</code>* if we are supposed to shut down.*/private synchronized Socket await() { //HttpProcessor.awati() 方法// Wait for the Connector to provide a new Socketwhile (!available) {try {wait();} catch (InterruptedException e) {}}// Notify the Connector that we have received this SocketSocket socket = this.socket;available = false;notifyAll();if ((debug >= 1) && (socket != null))log("  The incoming request has been awaited");return (socket);}

public final class Bootstrap {public static void main(String[] args) {HttpConnector connector = new HttpConnector();SimpleContainer container = new SimpleContainer(); // 创建容器connector.setContainer(container); // 将该 容器 和 http连接器 相关联try {connector.initialize();connector.start();// make the application wait until we press any key.System.in.read();}catch (Exception e) {e.printStackTrace();}}
}

补充-Complementary ends）

 public HttpProcessor(HttpConnector connector, int id) {super();this.connector = connector;this.debug = connector.getDebug();this.id = id;this.proxyName = connector.getProxyName();this.proxyPort = connector.getProxyPort();this.request = (HttpRequestImpl) connector.createRequest();this.response = (HttpResponseImpl) connector.createResponse();this.serverPort = connector.getPort();this.threadName ="HttpProcessor[" + connector.getPort() + "][" + id + "]";}

 public Request createRequest() {        HttpRequestImpl request = new HttpRequestImpl();request.setConnector(this);return (request);}

public Response createResponse() {HttpResponseImpl response = new HttpResponseImpl();response.setConnector(this);return (response);}

补充-Complementary2 ends）

E:\bench-cluster\cloud-data-preprocess\HowTomcatWorks\src>java -cp .;lib/servlet.jar;lib/catalina_4_1_24.jar;E:\bench-cluster\cloud-data-preprocess\HowTomcatWorks\webroot com.tomcat.chapter4.startup.Bootstrap
HttpConnector Opening server socket on all host IP addresses
HttpConnector[8080] Starting background thread
from service
from service