Tomcat：Tomcat启动时加载web.xml
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server.xml配置文件样例：
<?xml version="1.0" encoding="UTF-8"?> <!-- Licensed to the Apache Software Foundation (ASF) under one or more contributor license agreements. See the NOTICE file distributed with this work for additional information regarding copyright ownership. The ASF licenses this file to You under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at http://www.apache.org/licenses/LICENSE-2.0 Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License. --> <!-- Note: A "Server" is not itself a "Container", so you may not define subcomponents such as "Valves" at this level. Documentation at /docs/config/server.html --> <Server port="8005" shutdown="SHUTDOWN"> <Listener className="org.apache.catalina.startup.VersionLoggerListener"/> <!-- Security listener. Documentation at /docs/config/listeners.html <Listener className="org.apache.catalina.security.SecurityListener" /> --> <!--APR library loader. Documentation at /docs/apr.html --> <Listener SSLEngine="on" className="org.apache.catalina.core.AprLifecycleListener"/> <!-- Prevent memory leaks due to use of particular java/javax APIs--> <Listener className="org.apache.catalina.core.JreMemoryLeakPreventionListener"/> <Listener className="org.apache.catalina.mbeans.GlobalResourcesLifecycleListener"/> <Listener className="org.apache.catalina.core.ThreadLocalLeakPreventionListener"/> <!-- Global JNDI resources Documentation at /docs/jndi-resources-howto.html --> <GlobalNamingResources> <!-- Editable user database that can also be used by UserDatabaseRealm to authenticate users --> <Resource auth="Container" description="User database that can be updated and saved" factory="org.apache.catalina.users.MemoryUserDatabaseFactory" name="UserDatabase" pathname="conf/tomcat-users.xml" type="org.apache.catalina.UserDatabase"/> </GlobalNamingResources> <!-- A "Service" is a collection of one or more "Connectors" that share a single "Container" Note: A "Service" is not itself a "Container", so you may not define subcomponents such as "Valves" at this level. Documentation at /docs/config/service.html --> <Service name="Catalina"> <!--The connectors can use a shared executor, you can define one or more named thread pools--> <!-- <Executor name="tomcatThreadPool" namePrefix="catalina-exec-" maxThreads="150" minSpareThreads="4"/> --> <!-- A "Connector" represents an endpoint by which requests are received and responses are returned. Documentation at : Java HTTP Connector: /docs/config/http.html Java AJP Connector: /docs/config/ajp.html APR (HTTP/AJP) Connector: /docs/apr.html Define a non-SSL/TLS HTTP/1.1 Connector on port 8080 --> <Connector connectionTimeout="20000" port="8080" protocol="HTTP/1.1" redirectPort="8443"/> <!-- A "Connector" using the shared thread pool--> <!-- <Connector executor="tomcatThreadPool" port="8080" protocol="HTTP/1.1" connectionTimeout="20000" redirectPort="8443" /> --> <!-- Define an SSL/TLS HTTP/1.1 Connector on port 8443 This connector uses the NIO implementation. The default SSLImplementation will depend on the presence of the APR/native library and the useOpenSSL attribute of the AprLifecycleListener. Either JSSE or OpenSSL style configuration may be used regardless of the SSLImplementation selected. JSSE style configuration is used below. --> <!-- <Connector port="8443" protocol="org.apache.coyote.http11.Http11NioProtocol" maxThreads="150" SSLEnabled="true"> <SSLHostConfig> <Certificate certificateKeystoreFile="conf/localhost-rsa.jks" type="RSA" /> </SSLHostConfig> </Connector> --> <!-- Define an SSL/TLS HTTP/1.1 Connector on port 8443 with HTTP/2 This connector uses the APR/native implementation which always uses OpenSSL for TLS. Either JSSE or OpenSSL style configuration may be used. OpenSSL style configuration is used below. --> <!-- <Connector port="8443" protocol="org.apache.coyote.http11.Http11AprProtocol" maxThreads="150" SSLEnabled="true" > <UpgradeProtocol className="org.apache.coyote.http2.Http2Protocol" /> <SSLHostConfig> <Certificate certificateKeyFile="conf/localhost-rsa-key.pem" certificateFile="conf/localhost-rsa-cert.pem" certificateChainFile="conf/localhost-rsa-chain.pem" type="RSA" /> </SSLHostConfig> </Connector> --> <!-- Define an AJP 1.3 Connector on port 8009 --> <Connector port="8009" protocol="AJP/1.3" redirectPort="8443"/> <!-- An Engine represents the entry point (within Catalina) that processes every request. The Engine implementation for Tomcat stand alone analyzes the HTTP headers included with the request, and passes them on to the appropriate Host (virtual host). Documentation at /docs/config/engine.html --> <!-- You should set jvmRoute to support load-balancing via AJP ie : <Engine name="Catalina" defaultHost="localhost" jvmRoute="jvm1"> --> <Engine defaultHost="localhost" name="Catalina"> <!--For clustering, please take a look at documentation at: /docs/cluster-howto.html (simple how to) /docs/config/cluster.html (reference documentation) --> <!-- <Cluster className="org.apache.catalina.ha.tcp.SimpleTcpCluster"/> --> <!-- Use the LockOutRealm to prevent attempts to guess user passwords via a brute-force attack --> <Realm className="org.apache.catalina.realm.LockOutRealm"> <!-- This Realm uses the UserDatabase configured in the global JNDI resources under the key "UserDatabase". Any edits that are performed against this UserDatabase are immediately available for use by the Realm. --> <Realm className="org.apache.catalina.realm.UserDatabaseRealm" resourceName="UserDatabase"/> </Realm> <Host appBase="webapps" autoDeploy="true" name="localhost" unpackWARs="true"> <!-- SingleSignOn valve, share authentication between web applications Documentation at: /docs/config/valve.html --> <!-- <Valve className="org.apache.catalina.authenticator.SingleSignOn" /> --> <!-- Access log processes all example. Documentation at: /docs/config/valve.html Note: The pattern used is equivalent to using pattern="common" --> <Valve className="org.apache.catalina.valves.AccessLogValve" directory="logs" pattern="%h %l %u %t "%r" %s %b" refix="localhost_access_log" suffix=".txt"/> <Context docBase="mybaits-test-dynamic-sql" path="/mybaits-test-dynamic-sql" reloadable="true" source="org.eclipse.jst.j2ee.server:mybaits-test-dynamic-sql"/> </Host> <!--spring_security_01_war--> <Host name="lhd.myweb.com" appBase="/opt/apache-tomcat-8.5.49/webapps" unpackWARs="true" autoDeploy="true"> <Context docBase="/opt/apache-tomcat-8.5.49/webapps/spring_security_01_war" path="" /> <Valve className="org.apache.catalina.valves.AccessLogValve" directory="logs" pattern="%h %l %u %t "%r" %s %b" refix="localhost_access_log" suffix=".txt"/> </Host> </Engine> </Service> <Service name="Catalina2"> <Connector connectionTimeout="20000" port="8200" protocol="HTTP/1.1" redirectPort="8443"/> <Connector port="8010" protocol="AJP/1.3" redirectPort="8443"/> <Engine defaultHost="localhost" name="Catalina"> <Realm className="org.apache.catalina.realm.LockOutRealm"> <Realm className="org.apache.catalina.realm.UserDatabaseRealm" resourceName="UserDatabase"/> </Realm> <!--spring_security_01_war--> <Host name="lhd.myweb.com" appBase="/opt/apache-tomcat-8.5.49/webapps" unpackWARs="true" autoDeploy="true"> <Context docBase="/opt/apache-tomcat-8.5.49/webapps/spring_security_01_war" path="" /> <Valve className="org.apache.catalina.valves.AccessLogValve" directory="logs" pattern="%h %l %u %t "%r" %s %b" refix="localhost_access_log" suffix=".txt"/> </Host> </Engine> </Service> </Server>
在Tomcat启动时，会加载并解析tomcat安装目录/conf/server.xml文件，在server.xml配置文件中通过Host或Content进行web应用加载：
1）Host配置： 在tomcat的server.xml中默认Host配置：
<Host appBase="webapps" autoDeploy="true" name="localhost" unpackWARs="true">
如此设置则会自动加载webapps下的文件夹或者war包。
2）Content配置：
<Context docBase="/xxxxx" path="/xxxx" reloadable="true" ></Context>
如此则会加载指定的context。
备注：
样例server.xml访问站点的方式包含：
1）http://localhost:8080/mybaits-test-dynamic-sql
2）http://lhd.myweb.com:8080/
3）http://lhd.myweb.com:8200/
1）配置Host的appBase则可以自动加载appBase文件夹下的应用
1.1）查看StandardHost的startInternal方法：
/** * Start this component and implement the requirements * of {@link org.apache.catalina.util.LifecycleBase#startInternal()}. * * @exception LifecycleException if this component detects a fatal error * that prevents this component from being used */ @Override protected synchronized void startInternal() throws LifecycleException { // Set error report valve String errorValve = getErrorReportValveClass(); if ((errorValve != null) && (!errorValve.equals(""))) { try { boolean found = false; Valve[] valves = getPipeline().getValves(); for (Valve valve : valves) { if (errorValve.equals(valve.getClass().getName())) { found = true; break; } } if(!found) { Valve valve = (Valve) Class.forName(errorValve).getConstructor().newInstance(); getPipeline().addValve(valve); } } catch (Throwable t) { ExceptionUtils.handleThrowable(t); log.error(sm.getString("standardHost.invalidErrorReportValveClass", errorValve), t); } } super.startInternal(); }
Super.startInternal()方法是ContainerBase.java中的方法：
/** * Start this component and implement the requirements * of {@link org.apache.catalina.util.LifecycleBase#startInternal()}. * * @exception LifecycleException if this component detects a fatal error * that prevents this component from being used */ @Override protected synchronized void startInternal() throws LifecycleException { // Start our subordinate components, if any logger = null; getLogger(); Cluster cluster = getClusterInternal(); if (cluster instanceof Lifecycle) { ((Lifecycle) cluster).start(); } Realm realm = getRealmInternal(); if (realm instanceof Lifecycle) { ((Lifecycle) realm).start(); } // Start our child containers, if any Container children[] = findChildren(); List<Future<Void>> results = new ArrayList<>(); for (int i = 0; i < children.length; i++) { results.add(startStopExecutor.submit(new StartChild(children[i]))); } MultiThrowable multiThrowable = null; for (Future<Void> result : results) { try { result.get(); } catch (Throwable e) { log.error(sm.getString("containerBase.threadedStartFailed"), e); if (multiThrowable == null) { multiThrowable = new MultiThrowable(); } multiThrowable.add(e); } } if (multiThrowable != null) { throw new LifecycleException(sm.getString("containerBase.threadedStartFailed"), multiThrowable.getThrowable()); } // Start the Valves in our pipeline (including the basic), if any if (pipeline instanceof Lifecycle) { ((Lifecycle) pipeline).start(); } setState(LifecycleState.STARTING); // Start our thread threadStart(); }
查看ContainerBase#startInternal()中调用了ContainerBase#setState(LifecycleState.STARTING);
/** * Provides a mechanism for sub-classes to update the component state. * Calling this method will automatically fire any associated * {@link Lifecycle} event. It will also check that any attempted state * transition is valid for a sub-class. * * @param state The new state for this component * @throws LifecycleException when attempting to set an invalid state */ protected synchronized void setState(LifecycleState state) throws LifecycleException { setStateInternal(state, null, true); }
查看ContainerBase#setState(LifecycleState state)方法内部调用了ContainerBase#setStateInternal(state,null,true)方法：
private synchronized void setStateInternal(LifecycleState state, Object data, boolean check) throws LifecycleException { if (log.isDebugEnabled()) { log.debug(sm.getString("lifecycleBase.setState", this, state)); } if (check) { // Must have been triggered by one of the abstract methods (assume // code in this class is correct) // null is never a valid state if (state == null) { invalidTransition("null"); // Unreachable code - here to stop eclipse complaining about // a possible NPE further down the method return; } // Any method can transition to failed // startInternal() permits STARTING_PREP to STARTING // stopInternal() permits STOPPING_PREP to STOPPING and FAILED to // STOPPING if (!(state == LifecycleState.FAILED || (this.state == LifecycleState.STARTING_PREP && state == LifecycleState.STARTING) || (this.state == LifecycleState.STOPPING_PREP && state == LifecycleState.STOPPING) || (this.state == LifecycleState.FAILED && state == LifecycleState.STOPPING))) { // No other transition permitted invalidTransition(state.name()); } } this.state = state; String lifecycleEvent = state.getLifecycleEvent(); if (lifecycleEvent != null) { fireLifecycleEvent(lifecycleEvent, data); } }
在ContainerBase#setStateInternal()内部调用了ContainerBase#fireLifecycleEvent(lifecycleEvent,data);方法：
/** * The list of registered LifecycleListeners for event notifications. */ private final List<LifecycleListener> lifecycleListeners = new CopyOnWriteArrayList<>(); /** * Allow sub classes to fire {@link Lifecycle} events. * * @param type Event type * @param data Data associated with event. */ protected void fireLifecycleEvent(String type, Object data) { LifecycleEvent event = new LifecycleEvent(this, type, data); for (LifecycleListener listener : lifecycleListeners) { listener.lifecycleEvent(event); } }
StandardHost在启动时，会通知所有listener它的启动状态，而StandardHost有一个默认listener是HostConfig，所以会调用到HostConfig的lifecycleEvent方法。
LifecycleListener接口的实现类：
1.2）查看HostConfig的lifecycleEvent方法：
查看HostConfig#lifecycleEvent()方法代码：
/** * Process the START event for an associated Host. * * @param event The lifecycle event that has occurred */ @Override public void lifecycleEvent(LifecycleEvent event) { // Identify the host we are associated with try { host = (Host) event.getLifecycle(); if (host instanceof StandardHost) { setCopyXML(((StandardHost) host).isCopyXML()); setDeployXML(((StandardHost) host).isDeployXML()); setUnpackWARs(((StandardHost) host).isUnpackWARs()); setContextClass(((StandardHost) host).getContextClass()); } } catch (ClassCastException e) { log.error(sm.getString("hostConfig.cce", event.getLifecycle()), e); return; } // Process the event that has occurred if (event.getType().equals(Lifecycle.PERIODIC_EVENT)) { check(); } else if (event.getType().equals(Lifecycle.BEFORE_START_EVENT)) { beforeStart(); } else if (event.getType().equals(Lifecycle.START_EVENT)) { start(); } else if (event.getType().equals(Lifecycle.STOP_EVENT)) { stop(); } }
在HostConfig#lifecycleEvent()方法内部会调用HostConfig#start()方法：
/** * Process a "start" event for this Host. */ public void start() { if (log.isDebugEnabled()) log.debug(sm.getString("hostConfig.start")); try { ObjectName hostON = host.getObjectName(); oname = new ObjectName (hostON.getDomain() + ":type=Deployer,host=" + host.getName()); Registry.getRegistry(null, null).registerComponent (this, oname, this.getClass().getName()); } catch (Exception e) { log.warn(sm.getString("hostConfig.jmx.register", oname), e); } if (!host.getAppBaseFile().isDirectory()) { log.error(sm.getString("hostConfig.appBase", host.getName(), host.getAppBaseFile().getPath())); host.setDeployOnStartup(false); host.setAutoDeploy(false); } if (host.getDeployOnStartup()) deployApps(); }
在HostConfig#start()内部会调用HostConfig#deployApps()方法：
/** * Deploy applications for any directories or WAR files that are found * in our "application root" directory. */ 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()); // Deploy WARs deployWARs(appBase, filteredAppPaths); // Deploy expanded folders deployDirectories(appBase, filteredAppPaths); }
在HostConfig#deployApps()方法内部会一次调用deployWARs(appBase,filteredAppPaths);和deployDirectories(appBase,filteredAppPaths);方法：
/** * Deploy exploded webapps. * @param appBase The base path for applications * @param files The exploded webapps that should be deployed */ 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); } } }
在HostConfig#deployDirectories()方法内部调用了ExecutorService#submit(new DeployDirectory(this,cn,dir));，对于每一个文件夹，提交了一个部署任务。
1.3）查看DeployDirectory的run方法：
private static class DeployDirectory implements Runnable { private HostConfig config; private ContextName cn; private File dir; public DeployDirectory(HostConfig config, ContextName cn, File dir) { this.config = config; this.cn = cn; this.dir = dir; } @Override public void run() { config.deployDirectory(cn, dir); } }
在DeployDirectory#run()内部调用config.deployDirectory(cn,dir);代码，HostConfig#deployDirectory(cn,dir)方法内部代码：
/** * Deploy exploded webapp. * @param cn The context name * @param dir The path to the root folder of the weapp */ protected void deployDirectory(ContextName cn, File dir) { long startTime = 0; // Deploy the application in this directory if( log.isInfoEnabled() ) { startTime = System.currentTimeMillis(); log.info(sm.getString("hostConfig.deployDir", dir.getAbsolutePath())); } Context context = null; File xml = new File(dir, Constants.ApplicationContextXml); File xmlCopy = new File(host.getConfigBaseFile(), cn.getBaseName() + ".xml"); DeployedApplication deployedApp; boolean copyThisXml = isCopyXML(); boolean deployThisXML = isDeployThisXML(dir, cn); try { if (deployThisXML && xml.exists()) { synchronized (digesterLock) { try { context = (Context) digester.parse(xml); } catch (Exception e) { log.error(sm.getString( "hostConfig.deployDescriptor.error", xml), e); context = new FailedContext(); } finally { digester.reset(); if (context == null) { context = new FailedContext(); } } } if (copyThisXml == false && context instanceof StandardContext) { // Host is using default value. Context may override it. copyThisXml = ((StandardContext) context).getCopyXML(); } if (copyThisXml) { Files.copy(xml.toPath(), xmlCopy.toPath()); context.setConfigFile(xmlCopy.toURI().toURL()); } else { context.setConfigFile(xml.toURI().toURL()); } } else if (!deployThisXML && xml.exists()) { // Block deployment as META-INF/context.xml may contain security // configuration necessary for a secure deployment. log.error(sm.getString("hostConfig.deployDescriptor.blocked", cn.getPath(), xml, xmlCopy)); context = new FailedContext(); } else { context = (Context) Class.forName(contextClass).getConstructor().newInstance(); } Class<?> clazz = Class.forName(host.getConfigClass()); LifecycleListener listener = (LifecycleListener) clazz.ge以上是关于Tomcat：Tomcat启动时加载web.xml的主要内容，如果未能解决你的问题，请参考以下文章