// invoke each valve added to the pipeline，先是非基础阀调用 invoke方法
for(;;){valve[i].invoke();
}
// then, invoke the basic valve， 后是基础阀调用 invoke方法（基础阀最后一个调用invoke方法）
basicValve.invoke(...);public void invoke(Request request, Response response) // SimplePipeline.invoke()throws IOException, ServletException {// Invoke the first Valve in this pipeline for this request(new SimplePipelineValveContext()).invokeNext(request, response);}
public void invokeNext(Request request, Response response) // SimplePipeline.invokeNext()throws IOException, ServletException {int subscript = stage;stage = stage + 1;// Invoke the requested Valve for the current request threadif (subscript < valves.length) {valves[subscript].invoke(request, response, this);}else if ((subscript == valves.length) && (basic != null)) {basic.invoke(request, response, this);}else {throw new ServletException("No valve");}}} // end of inner class

public interface Pipeline {public Valve getBasic();public void setBasic(Valve valve);public void addValve(Valve valve);public Valve[] getValves(); public void invoke(Request request, Response response) throws IOException, ServletException;public void removeValve(Valve valve); 
} 

public interface Valve {public String getInfo();                                                                              
　　 public void invoke(Request request, Response response,ValveContext context) throws IOException, ServletException;

public interface Contained {   public Container getContainer();public void setContainer(Container container);
} 

public interface Wrapper extends Container {     public long getAvailable();public void setAvailable(long available);public String getJspFile(); public void setJspFile(String jspFile); public int getLoadOnStartup(); public void setLoadOnStartup(int value); public String getRunAs(); public void setRunAs(String runAs); public String getServletClass(); public void setServletClass(String servletClass); public boolean isUnavailable(); public void addInitParameter(String name, String value);     public void addInstanceListener(InstanceListener listener);     public void addSecurityReference(String name, String link);     public Servlet allocate() throws ServletException;     public void deallocate(Servlet servlet) throws ServletException;     public String findInitParameter(String name);    public String[] findInitParameters();     public String findSecurityReference(String name);     public String[] findSecurityReferences();    public void load() throws ServletException;    public void removeInitParameter(String name); public void removeInstanceListener(InstanceListener listener);     public void removeSecurityReference(String name);  public void unavailable(UnavailableException unavailable);   public void unload() throws ServletException;
}

public class SimpleLoader implements Loader {public static final String WEB_ROOT =System.getProperty("user.dir") + File.separator  + "webroot";ClassLoader classLoader = null;Container container = null;public SimpleLoader() {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);classLoader = new URLClassLoader(urls);}catch (IOException e) {System.out.println(e.toString() );}}

public class SimplePipeline implements Pipeline {public SimplePipeline(Container container) {setContainer(container);}// The basic Valve (if any) associated with this Pipeline.protected Valve basic = null;// The Container with which this Pipeline is associated.protected Container container = null;// the array of Valvesprotected Valve valves[] = new Valve[0];public void setContainer(Container container) {this.container = container;}public Valve getBasic() {return basic;}public void setBasic(Valve valve) {this.basic = valve;((Contained) valve).setContainer(container);}public void addValve(Valve valve) {if (valve instanceof Contained)((Contained) valve).setContainer(this.container);synchronized (valves) {Valve results[] = new Valve[valves.length +1];System.arraycopy(valves, 0, results, 0, valves.length);results[valves.length] = valve;valves = results;}}public Valve[] getValves() {return valves;}public void invoke(Request request, Response response)throws IOException, ServletException {// Invoke the first Valve in this pipeline for this request(new SimplePipelineValveContext()).invokeNext(request, response);}public void removeValve(Valve valve) {}// this class is copied from org.apache.catalina.core.StandardPipeline class's// StandardPipelineValveContext inner class.protected class SimplePipelineValveContext implements ValveContext {protected int stage = 0;public String getInfo() {return null;}public void invokeNext(Request request, Response response)throws IOException, ServletException {int subscript = stage;stage = stage + 1;// Invoke the requested Valve for the current request threadif (subscript < valves.length) {valves[subscript].invoke(request, response, this);}else if ((subscript == valves.length) && (basic != null)) {basic.invoke(request, response, this);}else {throw new ServletException("No valve");}}} // end of inner class
}

public class SimpleWrapper implements Wrapper, Pipeline {// the servlet instanceprivate Servlet instance = null;private String servletClass;private Loader loader;private String name;private SimplePipeline pipeline = new SimplePipeline(this);protected Container parent = null;public SimpleWrapper() {pipeline.setBasic(new SimpleWrapperValve());}public synchronized void addValve(Valve valve) {pipeline.addValve(valve);}public Servlet allocate() throws ServletException {// Load and initialize our instance if necessaryif (instance==null) {try {instance = loadServlet();}catch (ServletException e) {throw e;}catch (Throwable e) {throw new ServletException("Cannot allocate a servlet instance", e);}}return instance;}private Servlet loadServlet() throws ServletException {if (instance!=null)return instance;Servlet servlet = null;String actualClass = servletClass;if (actualClass == null) {throw new ServletException("servlet class has not been specified");}Loader loader = getLoader();// Acquire an instance of the class loader to be usedif (loader==null) {throw new ServletException("No loader.");}ClassLoader classLoader = loader.getClassLoader();// Load the specified servlet class from the appropriate class loaderClass classClass = null;try {if (classLoader!=null) {classClass = classLoader.loadClass(actualClass);}}catch (ClassNotFoundException e) {throw new ServletException("Servlet class not found");}// Instantiate and initialize an instance of the servlet class itselftry {servlet = (Servlet) classClass.newInstance();}catch (Throwable e) {throw new ServletException("Failed to instantiate servlet");}// Call the initialization method of this servlettry {servlet.init(null);}catch (Throwable f) {throw new ServletException("Failed initialize servlet.");}return servlet;}public String getInfo() {return null;}public Loader getLoader() {if (loader != null)return (loader);if (parent != null)return (parent.getLoader());return (null);}

public class SimpleWrapperValve implements Valve, Contained {protected Container container;public void invoke(Request request, Response response, ValveContext valveContext)throws IOException, ServletException {SimpleWrapper wrapper = (SimpleWrapper) getContainer();ServletRequest sreq = request.getRequest();ServletResponse sres = response.getResponse();Servlet servlet = null;HttpServletRequest hreq = null;if (sreq instanceof HttpServletRequest)hreq = (HttpServletRequest) sreq;HttpServletResponse hres = null;if (sres instanceof HttpServletResponse)hres = (HttpServletResponse) sres;// Allocate a servlet instance to process this requesttry {servlet = wrapper.allocate();if (hres!=null && hreq!=null) {servlet.service(hreq, hres);}else {servlet.service(sreq, sres);}}catch (ServletException e) {}}public String getInfo() {return null;}public Container getContainer() {return container;}public void setContainer(Container container) {this.container = container;}
}

public class ClientIPLoggerValve implements Valve, Contained {protected Container container;public void invoke(Request request, Response response, ValveContext valveContext)throws IOException, ServletException {// Pass this request on to the next valve in our pipelinevalveContext.invokeNext(request, response);System.out.println("Client IP Logger Valve");ServletRequest sreq = request.getRequest();System.out.println(sreq.getRemoteAddr());System.out.println("------------------------------------");}public String getInfo() {return null;}public Container getContainer() {return container;}public void setContainer(Container container) {this.container = container;}
}

public class HeaderLoggerValve implements Valve, Contained {protected Container container;public void invoke(Request request, Response response, ValveContext valveContext)throws IOException, ServletException {// Pass this request on to the next valve in our pipelinevalveContext.invokeNext(request, response);System.out.println("Header Logger Valve");ServletRequest sreq = request.getRequest();if (sreq instanceof HttpServletRequest) {HttpServletRequest hreq = (HttpServletRequest) sreq;Enumeration headerNames = hreq.getHeaderNames();while (headerNames.hasMoreElements()) {String headerName = headerNames.nextElement().toString();String headerValue = hreq.getHeader(headerName);System.out.println(headerName + ":" + headerValue);}}elseSystem.out.println("Not an HTTP Request");System.out.println("------------------------------------");}public String getInfo() {return null;}public Container getContainer() {return container;}public void setContainer(Container container) {this.container = container;}
}

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.chapter5.startup/Bootstrap1 
HttpConnector Opening server socket on all host IP addresses
HttpConnector[8080] Starting background thread
ModernServlet -- init
Client IP Logger Valve
127.0.0.1
------------------------------------
Header Logger Valve
host:localhost:8080
connection:keep-alive
accept:text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8
user-agent:Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/39.0.2171.71 Safari/537.36
accept-encoding:gzip, deflate, sdch
accept-language:zh-CN,zh;q=0.8,en;q=0.6
------------------------------------
Client IP Logger Valve
127.0.0.1
------------------------------------
Header Logger Valve
host:localhost:8080
connection:keep-alive
accept:text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8
user-agent:Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/39.0.2171.71 Safari/537.36
accept-encoding:gzip, deflate, sdch
accept-language:zh-CN,zh;q=0.8,en;q=0.6
------------------------------------

public class SimpleContextMapper implements Mapper {/*** The Container with which this Mapper is associated.*/private SimpleContext context = null;public Container getContainer() {return (context);}public void setContainer(Container container) {if (!(container instanceof SimpleContext))throw new IllegalArgumentException("Illegal type of container");context = (SimpleContext) container;}public String getProtocol() {return null;}public void setProtocol(String protocol) {}/*** Return the child Container that should be used to process this Request,* based upon its characteristics.  If no such child Container can be* identified, return <code>null</code> instead.** @param request Request being processed* @param update Update the Request to reflect the mapping selection?** @exception IllegalArgumentException if the relative portion of the*  path cannot be URL decoded*/public Container map(Request request, boolean update) {// Identify the context-relative URI to be mappedString contextPath =((HttpServletRequest) request.getRequest()).getContextPath();String requestURI = ((HttpRequest) request).getDecodedRequestURI();String relativeURI = requestURI.substring(contextPath.length());// Apply the standard request URI mapping rules from the specificationWrapper wrapper = null;String servletPath = relativeURI;String pathInfo = null;String name = context.findServletMapping(relativeURI);if (name != null)wrapper = (Wrapper) context.findChild(name);return (wrapper);}
}

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.chapter5.startup.
Bootstrap2
HttpConnector Opening server socket on all host IP addresses
HttpConnector[8080] Starting background thread
Client IP Logger Valve
127.0.0.1
------------------------------------
Header Logger Valve
host:localhost:8080
connection:keep-alive
accept:text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8
user-agent:Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/39.0.2171.71 Safari/537.36
accept-encoding:gzip, deflate, sdch
accept-language:zh-CN,zh;q=0.8,en;q=0.6
------------------------------------
init
from service
Client IP Logger Valve
127.0.0.1
------------------------------------