下面是tomcat start的一部分UML
Bootstrap.start()
public void start()
throws Exception {
if( catalinaDaemon==null ) init();
Method method = catalinaDaemon.getClass().getMethod("start", (Class [] )null);
method.invoke(catalinaDaemon, (Object [])null);
}以上是在Bootstrap應用反射調用Catalina start方法.
Catalina.start()
/**
* Start a new server instance. 啓動server
*/
public void start() {
if (server == null) {
load();
}
long t1 = System.nanoTime();
// Start the new server
if (server instanceof Lifecycle) {//只有實現Lifecycle才能調用start
try {
((Lifecycle) server).start();
} catch (LifecycleException e) {
log.error("Catalina.start: ", e);
}
}
long t2 = System.nanoTime();
if(log.isInfoEnabled())
log.info("Server startup in " + ((t2 - t1) / 1000000) + " ms");
try {
// Register shutdown hook
if (useShutdownHook) { //添加關閉鉤子，使系統exit時，能做一些資源回收處理
if (shutdownHook == null) {
shutdownHook = new CatalinaShutdownHook();
}
Runtime.getRuntime().addShutdownHook(shutdownHook);
}
} catch (Throwable t) {
// This will fail on JDK 1.2. Ignoring, as Tomcat can run
// fine without the shutdown hook.
}
if (await) {
await();
stop();
}
}
StandardServer.start
public void start() throws LifecycleException {
// Validate and update our current component state
if (started) {
log.debug(sm.getString("standardServer.start.started"));
return;
}
// Notify our interested LifecycleListeners
lifecycle.fireLifecycleEvent(BEFORE_START_EVENT, null);//觸發相應的事件
lifecycle.fireLifecycleEvent(START_EVENT, null);
started = true;
// Start our defined Services
synchronized (services) {
for (int i = 0; i < services.length; i++) { //啓動service
if (services[i] instanceof Lifecycle)
((Lifecycle) services[i]).start();
}
}
// Notify our interested LifecycleListeners
lifecycle.fireLifecycleEvent(AFTER_START_EVENT, null);
}
StandardService.start()
public void start() throws LifecycleException {
// Validate and update our current component state
if (log.isInfoEnabled() && started) {
log.info(sm.getString("standardService.start.started"));
}
if( ! initialized )
init();
// Notify our interested LifecycleListeners
lifecycle.fireLifecycleEvent(BEFORE_START_EVENT, null); //觸發感興趣的事件
if(log.isInfoEnabled())
log.info(sm.getString("standardService.start.name", this.name));
lifecycle.fireLifecycleEvent(START_EVENT, null);
started = true;
// Start our defined Container first
if (container != null) {
synchronized (container) {
if (container instanceof Lifecycle) {//啓動容器
((Lifecycle) container).start();
}
}
}
synchronized (executors) {
for ( int i=0; i<executors.size(); i++ ) {
executors.get(i).start();
}
}
// Start our defined Connectors second
synchronized (connectors) {
for (int i = 0; i < connectors.length; i++) {//啓動connector,這裏就可以監聽客戶端請求
if (connectors[i] instanceof Lifecycle)
((Lifecycle) connectors[i]).start();
}
}
// Notify our interested LifecycleListeners
lifecycle.fireLifecycleEvent(AFTER_START_EVENT, null);
}StandardEngine.start()
public void start() throws LifecycleException {
if( started ) {
return;
}
if( !initialized ) {
init();
}
// Look for a realm - that may have been configured earlier.
// If the realm is added after context - it'll set itself.
if( realm == null ) {//註冊mbean
ObjectName realmName=null;
try {
realmName=new ObjectName( domain + ":type=Realm");
if( mserver.isRegistered(realmName ) ) {
mserver.invoke(realmName, "init",
new Object[] {},
new String[] {}
);
}
} catch( Throwable t ) {
log.debug("No realm for this engine " + realmName);
}
}
// Log our server identification information
//System.out.println(ServerInfo.getServerInfo());
if(log.isInfoEnabled())
log.info( "Starting Servlet Engine: " + ServerInfo.getServerInfo());
if( mbeans != null ) {
try {
Registry.getRegistry(null, null)
.invoke(mbeans, "start", false);
} catch (Exception e) {
log.error("Error in start() for " + mbeansFile, e);
}
}
// Standard container startup
super.start();//這裏調用父類的start
}
由於StandardHost和StandardEngine有共同的方法，所以這裏都抽象到ContainerBase中，那麼我們看看ContainerBase.start是怎麼實現的
public synchronized void start() throws LifecycleException {
// Validate and update our current component state
if (started) {
if(log.isInfoEnabled())
log.info(sm.getString("containerBase.alreadyStarted", logName()));
return;
}
// Notify our interested LifecycleListeners
lifecycle.fireLifecycleEvent(BEFORE_START_EVENT, null);
started = true;
// Start our subordinate components, if any
if ((loader != null) && (loader instanceof Lifecycle))
((Lifecycle) loader).start();
logger = null;
getLogger();
if ((logger != null) && (logger instanceof Lifecycle))
((Lifecycle) logger).start();
if ((manager != null) && (manager instanceof Lifecycle))
((Lifecycle) manager).start();
if ((cluster != null) && (cluster instanceof Lifecycle))
((Lifecycle) cluster).start();
if ((realm != null) && (realm instanceof Lifecycle))
((Lifecycle) realm).start();
if ((resources != null) && (resources instanceof Lifecycle))
((Lifecycle) resources).start();
// Start our child containers, if any
Container children[] = findChildren();//查找子子容器
for (int i = 0; i < children.length; i++) {
if (children[i] instanceof Lifecycle)
((Lifecycle) children[i]).start();
}
// Start the Valves in our pipeline (including the basic), if any
if (pipeline instanceof Lifecycle)
((Lifecycle) pipeline).start();
// Notify our interested LifecycleListeners
lifecycle.fireLifecycleEvent(START_EVENT, null);
// Start our thread
threadStart();//啓動後臺定時線程
// Notify our interested LifecycleListeners
lifecycle.fireLifecycleEvent(AFTER_START_EVENT, null);
}上面查找子容器是StandardHost,我們進入start方法看看
public synchronized void start() throws LifecycleException {
if( started ) {
return;
}
if( ! initialized )//初始化
init();
// Look for a realm - that may have been configured earlier.
// If the realm is added after context - it'll set itself.
if( realm == null ) { //查找realm
ObjectName realmName=null;
try {
realmName=new ObjectName( domain + ":type=Realm,host=" + getName());
if( mserver.isRegistered(realmName ) ) {
mserver.invoke(realmName, "init",
new Object[] {},
new String[] {}
);
}
} catch( Throwable t ) {
log.debug("No realm for this host " + realmName);
}
}
// Set error report valve
if ((errorReportValveClass != null) //設置valve過濾器
&& (!errorReportValveClass.equals(""))) {
try {
boolean found = false;
if(errorReportValveObjectName != null) {
ObjectName[] names =
((StandardPipeline)pipeline).getValveObjectNames();
for (int i=0; !found && i<names.length; i++)
if(errorReportValveObjectName.equals(names[i]))
found = true ;
}
if(!found) {
Valve valve = (Valve) Class.forName(errorReportValveClass)
.newInstance();
addValve(valve);
errorReportValveObjectName = ((ValveBase)valve).getObjectName() ;
}
} catch (Throwable t) {
log.error(sm.getString
("standardHost.invalidErrorReportValveClass",
errorReportValveClass));
}
}
if(log.isDebugEnabled()) {
if (xmlValidation)
log.debug(sm.getString("standardHost.validationEnabled"));
else
log.debug(sm.getString("standardHost.validationDisabled"));
}
super.start();//調用父類的start
}如果在pipeline設置了Valves，那麼容器啓動過程中會依次調用valve
StandardPipeline.start
public synchronized void start() throws LifecycleException {
// Validate and update our current component state
if (started)
throw new LifecycleException
(sm.getString("standardPipeline.alreadyStarted"));
// Notify our interested LifecycleListeners
lifecycle.fireLifecycleEvent(BEFORE_START_EVENT, null);
started = true;
// Start the Valves in our pipeline (including the basic), if any
Valve current = first;
if (current == null) {
current = basic;
}
while (current != null) {//循環調用valve
if (current instanceof Lifecycle)
((Lifecycle) current).start();
registerValve(current);
current = current.getNext();
}
// Notify our interested LifecycleListeners
lifecycle.fireLifecycleEvent(START_EVENT, null);
// Notify our interested LifecycleListeners
lifecycle.fireLifecycleEvent(AFTER_START_EVENT, null);
}在Pipeline添加的valve將依次調用，這裏valve可以理解爲servlet中的過濾器。