一、启动类：Bootstrap.main()
二、项目运行时加载静态方法
CatalinaProperties.loadProperties()；加载conf/catalina.properties文件，放入到System.setProperty();
三、Bootstrap.initClassLoaders()类加载
3.1 读取catalina.properties中属性：common.loader，将属性指定的的tomcat/lib目录下的所有jar包全路径加载到
ClassLoader commonLoader = createClassLoader(“common”, null);
3.2 读取catalina.properties中属性：server.loader，如果没配置，则返回ClassLoader catalinaLoader=commonLoader；
3.3 读取catalina.properties中属性：shared.loader，如果没配置，则返回ClassLoader sharedLoader=commonLoader；
四、Catalina.load()容器初始化
4.1 Digester digester = createStartDigester();设定service.xml解析规则；
digester.parse(inputSource);将servive.xml文件解析成java对象；
4.2 容器初始化
getServer().init();–》
LifecycleBase.init()–》StandardServer.initInternal()–》services[i].init();
–》
LifecycleBase.init()–》StandardService.initInternal()–》
引擎初始化：engine.init();–》
LifecycleBase.init()–》StandardEngine.initInternal()
端口监听初始化：connector.init();–》
LifecycleBase.init()–》Connector.initInternal()–》 protocolHandler.init(); --》endpoint.init();–》AbstractJsseEndpoint.init()–》AbstractEndpoint.init()–》NioEndpoint.bind();
五、容器启动
六、代码解析
StandardService中的方法startInternal，负责启动引擎和8080端口监听
@Override
protected void startInternal() throws LifecycleException {
if(log.isInfoEnabled())
log.info(sm.getString("standardService.start.name", this.name));
setState(LifecycleState.STARTING);
// 启动引擎
if (engine != null) {
synchronized (engine) {
engine.start();
}
}
synchronized (executors) {
for (Executor executor: executors) {
executor.start();
}
}
mapperListener.start();
// 启动8080端口监听
synchronized (connectorsLock) {
for (Connector connector: connectors) {
try {
// If it has already failed, don't try and start it
if (connector.getState() != LifecycleState.FAILED) {
connector.start();
}
} catch (Exception e) {
log.error(sm.getString(
"standardService.connector.startFailed",
connector), e);
}
}
}
}
在HostConfig类中方法
protected void deployApps() {
File appBase = host.getAppBaseFile();
File configBase = host.getConfigBaseFile();
String[] filteredAppPaths = filterAppPaths(appBase.list());
// Deploy XML descriptors from configBase
deployDescriptors(configBase, configBase.list());
// 对发布的war包解压
deployWARs(appBase, filteredAppPaths);
//对发布的目录直接进行解析
deployDirectories(appBase, filteredAppPaths);
}
HostConfig类中此方法用到了java的future模式，主线程开启子线程，主线程继续异步执行，并且主线程可以通过get方法得到子线程的执行结果，提高了程序的执行效率；
future的参考资料：
https://www.cnblogs.com/cz123/p/7693064.html
http://www.cnblogs.com/dolphin0520/p/3949310.html
https://blog.csdn.net/u010365819/article/details/80761332
protected void deployDirectories(File appBase, String[] files) {
if (files == null)
return;
ExecutorService es = host.getStartStopExecutor();
List<Future<?>> results = new ArrayList<>();
for (int i = 0; i < files.length; i++) {
if (files[i].equalsIgnoreCase("META-INF"))
continue;
if (files[i].equalsIgnoreCase("WEB-INF"))
continue;
File dir = new File(appBase, files[i]);
if (dir.isDirectory()) {
ContextName cn = new ContextName(files[i], false);
if (isServiced(cn.getName()) || deploymentExists(cn.getName()))
continue;
results.add(es.submit(new DeployDirectory(this, cn, dir)));
}
}
for (Future<?> result : results) {
try {
result.get();
} catch (Exception e) {
log.error(sm.getString(
"hostConfig.deployDir.threaded.error"), e);
}
}
}
StandardContext中方法，加载web.xml，启动StandardWrapper，servlet初始化init
@Override
protected synchronized void startInternal() throws LifecycleException {
。。。。。
//在work目录下生成临时目录
postWorkDirectory();
。。。。。
//触发事件，开始加载web.xml文件
fireLifecycleEvent(Lifecycle.CONFIGURE_START_EVENT, null);
。。。。。。
//启动standardWrapper
for (Container child : findChildren()) {
if (!child.getState().isAvailable()) {
child.start();
}
}
。。。。。
//servlet初始化init()
// Load and initialize all "load on startup" servlets
if (ok) {
if (!loadOnStartup(findChildren())){
log.error(sm.getString("standardContext.servletFail"));
ok = false;
}
}
｝
ContextConfig类中方法，加载web.xml文件
protected synchronized void configureStart() {
// Called from StandardContext.start()
if (log.isDebugEnabled()) {
log.debug(sm.getString("contextConfig.start"));
}
if (log.isDebugEnabled()) {
log.debug(sm.getString("contextConfig.xmlSettings",
context.getName(),
Boolean.valueOf(context.getXmlValidation()),
Boolean.valueOf(context.getXmlNamespaceAware())));
}
//解析web.xml
webConfig();
if (!context.getIgnoreAnnotations()) {
applicationAnnotationsConfig();
}
if (ok) {
validateSecurityRoles();
}
// Configure an authenticator if we need one
if (ok) {
authenticatorConfig();
}
// Dump the contents of this pipeline if requested
if (log.isDebugEnabled()) {
log.debug("Pipeline Configuration:");
Pipeline pipeline = context.getPipeline();
Valve valves[] = null;
if (pipeline != null) {
valves = pipeline.getValves();
}
if (valves != null) {
for (int i = 0; i < valves.length; i++) {
log.debug(" " + valves[i].getClass().getName());
}
}
log.debug("======================");
}
// Make our application available if no problems were encountered
if (ok) {
context.setConfigured(true);
} else {
log.error(sm.getString("contextConfig.unavailable"));
context.setConfigured(false);
}
}
ContextConfig类中方法
protected void webConfig() {
WebXmlParser webXmlParser = new WebXmlParser(context.getXmlNamespaceAware(),
context.getXmlValidation(), context.getXmlBlockExternal());
//解析tomcat的conf目录下的web.xml文件
Set<WebXml> defaults = new HashSet<>();
defaults.add(getDefaultWebXmlFragment(webXmlParser));
WebXml webXml = createWebXml();
// 解析发布项目的web.xml文件
InputSource contextWebXml = getContextWebXmlSource();
if (!webXmlParser.parseWebXml(contextWebXml, webXml, false)) {
ok = false;
}
ServletContext sContext = context.getServletContext();
// Ordering is important here
//读取到jdk的jre目录下所有jar包
// Step 1. Identify all the JARs packaged with the application and those
// provided by the container. If any of the application JARs have a
// web-fragment.xml it will be parsed at this point. web-fragment.xml
// files are ignored for container provided JARs.
Map<String,WebXml> fragments = processJarsForWebFragments(webXml, webXmlParser);
// Step 2. Order the fragments.
Set<WebXml> orderedFragments = null;
orderedFragments =
WebXml.orderWebFragments(webXml, fragments, sContext);
// Step 3. Look for ServletContainerInitializer implementations
if (ok) {
processServletContainerInitializers();
}
if (!webXml.isMetadataComplete() || typeInitializerMap.size() > 0) {
// Step 4. Process /WEB-INF/classes for annotations and
// @HandlesTypes matches
Map<String,JavaClassCacheEntry> javaClassCache = new HashMap<>();
//加载所有class文件
if (ok) {
WebResource[] webResources =
context.getResources().listResources("/WEB-INF/classes");
for (WebResource webResource : webResources) {
// Skip the META-INF directory from any JARs that have been
// expanded in to WEB-INF/classes (sometimes IDEs do this).
if ("META-INF".equals(webResource.getName())) {
continue;
}
//将class文件装载到map中javaClassCache
processAnnotationsWebResource(webResource, webXml,
webXml.isMetadataComplete(), javaClassCache);
}
}
// Step 5. Process JARs for annotations and
// @HandlesTypes matches - only need to process those fragments we
// are going to use (remember orderedFragments includes any
// container fragments)
if (ok) {
//解析项目的web.xml文件
processAnnotations(
orderedFragments, webXml.isMetadataComplete(), javaClassCache);
}
// Cache, if used, is no longer required so clear it
javaClassCache.clear();
}
if (!webXml.isMetadataComplete()) {
// Step 6. Merge web-fragment.xml files into the main web.xml
// file.
if (ok) {
ok = webXml.merge(orderedFragments);
}
// Step 7. Apply global defaults
// Have to merge defaults before JSP conversion since defaults
// provide JSP servlet definition.
webXml.merge(defaults);
// Step 8. Convert explicitly mentioned jsps to servlets
if (ok) {
convertJsps(webXml);
}
// Step 9. Apply merged web.xml to Context
if (ok) {
configureContext(webXml);
}
} else {
//解析tomcat的web.xml文件
webXml.merge(defaults);
convertJsps(webXml);
//加载servlet，也就是StandardWrapper
configureContext(webXml);
}
if (context.getLogEffectiveWebXml()) {
log.info("web.xml:\n" + webXml.toXml());
}
// Always need to look for static resources
// Step 10. Look for static resources packaged in JARs
if (ok) {
// Spec does not define an order.
// Use ordered JARs followed by remaining JARs
Set<WebXml> resourceJars = new LinkedHashSet<>();
for (WebXml fragment : orderedFragments) {
resourceJars.add(fragment);
}
for (WebXml fragment : fragments.values()) {
if (!resourceJars.contains(fragment)) {
resourceJars.add(fragment);
}
}
processResourceJARs(resourceJars);
// See also StandardContext.resourcesStart() for
// WEB-INF/classes/META-INF/resources configuration
}
// Step 11. Apply the ServletContainerInitializer config to the
// context
if (ok) {
for (Map.Entry<ServletContainerInitializer,
Set<Class<?>>> entry :
initializerClassMap.entrySet()) {
if (entry.getValue().isEmpty()) {
context.addServletContainerInitializer(
entry.getKey(), null);
} else {
context.addServletContainerInitializer(
entry.getKey(), entry.getValue());
}
}
}
}
ContextConfig的configureContext方法负责初始化servlet，也就是StandardWrapper
private void configureContext(WebXml webxml) {
。。。。。
for (ServletDef servlet : webxml.getServlets().values()) {
Wrapper wrapper = context.createWrapper();
// Description is ignored
// Display name is ignored
// Icons are ignored
// jsp-file gets passed to the JSP Servlet as an init-param
if (servlet.getLoadOnStartup() != null) {
wrapper.setLoadOnStartup(servlet.getLoadOnStartup().intValue());
}
if (servlet.getEnabled() != null) {
wrapper.setEnabled(servlet.getEnabled().booleanValue());
}
wrapper.setName(servlet.getServletName());
Map<String,String> params = servlet.getParameterMap();
for (Entry<String, String> entry : params.entrySet()) {
wrapper.addInitParameter(entry.getKey(), entry.getValue());
}
wrapper.setRunAs(servlet.getRunAs());
Set<SecurityRoleRef> roleRefs = servlet.getSecurityRoleRefs();
for (SecurityRoleRef roleRef : roleRefs) {
wrapper.addSecurityReference(
roleRef.getName(), roleRef.getLink());
}
wrapper.setServletClass(servlet.getServletClass());
MultipartDef multipartdef = servlet.getMultipartDef();
if (multipartdef != null) {
if (multipartdef.getMaxFileSize() != null &&
multipartdef.getMaxRequestSize()!= null &&
multipartdef.getFileSizeThreshold() != null) {
wrapper.setMultipartConfigElement(new MultipartConfigElement(
multipartdef.getLocation(),
Long.parseLong(multipartdef.getMaxFileSize()),
Long.parseLong(multipartdef.getMaxRequestSize()),
Integer.parseInt(
multipartdef.getFileSizeThreshold())));
} else {
wrapper.setMultipartConfigElement(new MultipartConfigElement(
multipartdef.getLocation()));
}
}
if (servlet.getAsyncSupported() != null) {
wrapper.setAsyncSupported(
servlet.getAsyncSupported().booleanValue());
}
wrapper.setOverridable(servlet.isOverridable());
//启动StandardWrapper的startInternal方法
context.addChild(wrapper);
}
for (Entry<String, String> entry :
webxml.getServletMappings().entrySet()) {
context.addServletMappingDecoded(entry.getKey(), entry.getValue());
}
SessionConfig sessionConfig = webxml.getSessionConfig();
if (sessionConfig != null) {
if (sessionConfig.getSessionTimeout() != null) {
context.setSessionTimeout(
sessionConfig.getSessionTimeout().intValue());
}
SessionCookieConfig scc =
context.getServletContext().getSessionCookieConfig();
scc.setName(sessionConfig.getCookieName());
scc.setDomain(sessionConfig.getCookieDomain());
scc.setPath(sessionConfig.getCookiePath());
scc.setComment(sessionConfig.getCookieComment());
if (sessionConfig.getCookieHttpOnly() != null) {
scc.setHttpOnly(sessionConfig.getCookieHttpOnly().booleanValue());
}
if (sessionConfig.getCookieSecure() != null) {
scc.setSecure(sessionConfig.getCookieSecure().booleanValue());
}
if (sessionConfig.getCookieMaxAge() != null) {
scc.setMaxAge(sessionConfig.getCookieMaxAge().intValue());
}
if (sessionConfig.getSessionTrackingModes().size() > 0) {
context.getServletContext().setSessionTrackingModes(
sessionConfig.getSessionTrackingModes());
}
}
}
https://my.oschina.net/andylucc/blog/596046
Servlet容器对上下文参数、监听器、过滤器、Servlet的装配顺序为：上下文参数->过滤器->监听器->Servlet。
Servlet支持容器启动时加载、是否异步配置以及配置覆盖。
七、端口监听代码解析
StandardService中的方法startInternal，负责启动引擎和8080端口监听
@Override
protected void startInternal() throws LifecycleException {
if(log.isInfoEnabled())
log.info(sm.getString("standardService.start.name", this.name));
setState(LifecycleState.STARTING);
// 启动引擎
if (engine != null) {
synchronized (engine) {
engine.start();
}
}
synchronized (executors) {
for (Executor executor: executors) {
executor.start();
}
}
mapperListener.start();
// 启动8080端口监听
synchronized (connectorsLock) {
for (Connector connector: connectors) {
try {
// If it has already failed, don't try and start it
if (connector.getState() != LifecycleState.FAILED) {
connector.start();
}
} catch (Exception e) {
log.error(sm.getString(
"standardService.connector.startFailed",
connector), e);
}
}
}
}
Connector方法startInternal负责启动端口监听
@Override
protected void startInternal() throws LifecycleException {
// Validate settings before starting
if (getPort() < 0) {
throw new LifecycleException(sm.getString(
"coyoteConnector.invalidPort", Integer.valueOf(getPort())));
}
setState(LifecycleState.STARTING);
try {
//启动端口监听
protocolHandler.start();
} catch (Exception e) {
throw new LifecycleException(
sm.getString("coyoteConnector.protocolHandlerStartFailed"), e);
}
}
NioEndpoint类中方法startInternal调用方法startAcceptorThreads启动端口监听线程
/**
* Start the NIO endpoint, creating acceptor, poller threads.
*/
@Override
public void startInternal() throws Exception {
if (!running) {
running = true;
paused = false;
processorCache = new SynchronizedStack<>(SynchronizedStack.DEFAULT_SIZE,
socketProperties.getProcessorCache());
eventCache = new SynchronizedStack<>(SynchronizedStack.DEFAULT_SIZE,
socketProperties.getEventCache());
nioChannels = new SynchronizedStack<>(SynchronizedStack.DEFAULT_SIZE,
socketProperties.getBufferPool());
// Create worker collection
if ( getExecutor() == null ) {
createExecutor();
}
initializeConnectionLatch();
// Start poller threads
pollers = new Poller[getPollerThreadCount()];
for (int i=0; i<pollers.length; i++) {
pollers[i] = new Poller();
Thread pollerThread = new Thread(pollers[i], getName() + "-ClientPoller-"+i);
pollerThread.setPriority(threadPriority);
pollerThread.setDaemon(true);
pollerThread.start();
}
//启动端口监听线程
startAcceptorThreads();
}
}
AbstractEndpoint类中的方法
protected final void startAcceptorThreads() {
int count = getAcceptorThreadCount();
acceptors = new Acceptor[count];
for (int i = 0; i < count; i++) {
acceptors[i] = createAcceptor();
String threadName = getName() + "-Acceptor-" + i;
acceptors[i].setThreadName(threadName);
Thread t = new Thread(acceptors[i], threadName);
t.setPriority(getAcceptorThreadPriority());
t.setDaemon(getDaemon());
t.start();
}
}
识得庐山真面目
NioEndpoint的内部线程类Acceptor完成了8080端口的监听，往后的所有http请求都将进入到这个方法
protected class Acceptor extends AbstractEndpoint.Acceptor {
@Override
public void run() {
int errorDelay = 0;
// Loop until we receive a shutdown command
while (running) {
// Loop if endpoint is paused
while (paused && running) {
state = AcceptorState.PAUSED;
try {
Thread.sleep(50);
} catch (InterruptedException e) {
// Ignore
}
}
if (!running) {
break;
}
state = AcceptorState.RUNNING;
try {
//if we have reached max connections, wait
countUpOrAwaitConnection();
SocketChannel socket = null;
try {
// Accept the next incoming connection from the server
// 8080端口监听
socket = serverSock.accept();
} catch (IOException ioe) {
// We didn't get a socket
countDownConnection();
if (running) {
// Introduce delay if necessary
errorDelay = handleExceptionWithDelay(errorDelay);
// re-throw
throw ioe;
} else {
break;
}
}
// Successful accept, reset the error delay
errorDelay = 0;
// Configure the socket
if (running && !paused) {
// setSocketOptions() will hand the socket off to
// an appropriate processor if successful
if (!setSocketOptions(socket)) {
closeSocket(socket);
}
} else {
closeSocket(socket);
}
} catch (Throwable t) {
ExceptionUtils.handleThrowable(t);
log.error(sm.getString("endpoint.accept.fail"), t);
}
}
state = AcceptorState.ENDED;
}