文章源自JAVA秀-https://www.javaxiu.com/19939.html
前一章节回顾： 通过前一个章节的了解，我们基本上对web.xml和ServletContext有了一个比较深入的了解。但是web容器（tomcat或者jetty）是如何读取到web.xml文件的呢？又是如何将web.xml文件中的内容如何提取并解析到ServletContext的呢？本章节我们就来详细的了解一下。文章源自JAVA秀-https://www.javaxiu.com/19939.html
文章源自JAVA秀-https://www.javaxiu.com/19939.html
首先我们可以确定一点，当我们将war包放置到web容器的应用目录（比如tomcat的webapps目录）的时候，tomcat会解压该war包，然后到指定的文件目录读取web.xml文件，直到最后完成web后台服务的启动工作。因为本章节不涉及到tomcat的源码的细节跟踪，所以不会特别细的跟踪和解析没一行代码，只会关注和跟踪核心流程。另外我们需要知道一点StandardContext类的startInternal方法是tomcat容器启动web后台服务的最核心的模板方法，那么我们就从这个方法开始。文章源自JAVA秀-https://www.javaxiu.com/19939.html
1. web容器解析web.xml文件全过程解析
第一步：开始调用StandardContext类的startInternal方法，开始解析web.xml文件。这个就是tomcat容器在启动web后台服务的核心方法，本方法很长，但是我们核心关注的代码只有一行。文章源自JAVA秀-https://www.javaxiu.com/19939.html
@Override
protected synchronized void startInternal() throws LifecycleException {
if(log.isDebugEnabled())
log.debug("Starting " + getBaseName());
// Send j2ee.state.starting notification
if (this.getObjectName() != null) {
Notification notification = new Notification("j2ee.state.starting",
this.getObjectName(), sequenceNumber.getAndIncrement());
broadcaster.sendNotification(notification);
}
setConfigured(false);
boolean ok = true;
// Currently this is effectively a NO-OP but needs to be called to
// ensure the NamingResources follows the correct lifecycle
if (namingResources != null) {
namingResources.start();
}
// Post work directory
postWorkDirectory();
// Add missing components as necessary
if (getResources() == null) { // (1) Required by Loader
if (log.isDebugEnabled())
log.debug("Configuring default Resources");
try {
setResources(new StandardRoot(this));
} catch (IllegalArgumentException e) {
log.error(sm.getString("standardContext.resourcesInit"), e);
ok = false;
}
}
if (ok) {
resourcesStart();
}
if (getLoader() == null) {
WebappLoader webappLoader = new WebappLoader(getParentClassLoader());
webappLoader.setDelegate(getDelegate());
setLoader(webappLoader);
}
// An explicit cookie processor hasn't been specified; use the default
if (cookieProcessor == null) {
cookieProcessor = new Rfc6265CookieProcessor();
}
// Initialize character set mapper
getCharsetMapper();
// Validate required extensions
boolean dependencyCheck = true;
try {
dependencyCheck = ExtensionValidator.validateApplication
(getResources(), this);
} catch (IOException ioe) {
log.error(sm.getString("standardContext.extensionValidationError"), ioe);
dependencyCheck = false;
}
if (!dependencyCheck) {
// do not make application available if dependency check fails
ok = false;
}
// Reading the "catalina.useNaming" environment variable
String useNamingProperty = System.getProperty("catalina.useNaming");
if ((useNamingProperty != null)
&& (useNamingProperty.equals("false"))) {
useNaming = false;
}
if (ok && isUseNaming()) {
if (getNamingContextListener() == null) {
NamingContextListener ncl = new NamingContextListener();
ncl.setName(getNamingContextName());
ncl.setExceptionOnFailedWrite(getJndiExceptionOnFailedWrite());
addLifecycleListener(ncl);
setNamingContextListener(ncl);
}
}
// Standard container startup
if (log.isDebugEnabled())
log.debug("Processing standard container startup");
// Binding thread
ClassLoader oldCCL = bindThread();
try {
if (ok) {
// Start our subordinate components, if any
Loader loader = getLoader();
if (loader instanceof Lifecycle) {
((Lifecycle) loader).start();
}
// since the loader just started, the webapp classloader is now
// created.
setClassLoaderProperty("clearReferencesRmiTargets",
getClearReferencesRmiTargets());
setClassLoaderProperty("clearReferencesStopThreads",
getClearReferencesStopThreads());
setClassLoaderProperty("clearReferencesStopTimerThreads",
getClearReferencesStopTimerThreads());
setClassLoaderProperty("clearReferencesHttpClientKeepAliveThread",
getClearReferencesHttpClientKeepAliveThread());
setClassLoaderProperty("clearReferencesObjectStreamClassCaches",
getClearReferencesObjectStreamClassCaches());
setClassLoaderProperty("clearReferencesObjectStreamClassCaches",
getClearReferencesObjectStreamClassCaches());
setClassLoaderProperty("clearReferencesThreadLocals",
getClearReferencesThreadLocals());
// By calling unbindThread and bindThread in a row, we setup the
// current Thread CCL to be the webapp classloader
unbindThread(oldCCL);
oldCCL = bindThread();
// Initialize logger again. Other components might have used it
// too early, so it should be reset.
logger = null;
getLogger();
Realm realm = getRealmInternal();
if(null != realm) {
if (realm instanceof Lifecycle) {
((Lifecycle) realm).start();
}
// Place the CredentialHandler into the ServletContext so
// applications can have access to it. Wrap it in a "safe"
// handler so application's can't modify it.
CredentialHandler safeHandler = new CredentialHandler() {
@Override
public boolean matches(String inputCredentials, String storedCredentials) {
return getRealmInternal().getCredentialHandler().matches(inputCredentials, storedCredentials);
}
@Override
public String mutate(String inputCredentials) {
return getRealmInternal().getCredentialHandler().mutate(inputCredentials);
}
};
context.setAttribute(Globals.CREDENTIAL_HANDLER, safeHandler);
}
// Notify our interested LifecycleListeners
//关键行代码，在这行方法处，正式开始解析web.xml文件，前面的代码都是准备工作
fireLifecycleEvent(Lifecycle.CONFIGURE_START_EVENT, null);
// Start our child containers, if not already started
for (Container child : findChildren()) {
if (!child.getState().isAvailable()) {
child.start();
}
}
// Start the Valves in our pipeline (including the basic),
// if any
if (pipeline instanceof Lifecycle) {
((Lifecycle) pipeline).start();
}
// Acquire clustered manager
Manager contextManager = null;
Manager manager = getManager();
if (manager == null) {
if (log.isDebugEnabled()) {
log.debug(sm.getString("standardContext.cluster.noManager",
Boolean.valueOf((getCluster() != null)),
Boolean.valueOf(distributable)));
}
if ((getCluster() != null) && distributable) {
try {
contextManager = getCluster().createManager(getName());
} catch (Exception ex) {
log.error(sm.getString("standardContext.cluster.managerError"), ex);
ok = false;
}
} else {
contextManager = new StandardManager();
}
}
// Configure default manager if none was specified
if (contextManager != null) {
if (log.isDebugEnabled()) {
log.debug(sm.getString("standardContext.manager",
contextManager.getClass().getName()));
}
setManager(contextManager);
}
if (manager!=null && (getCluster() != null) && distributable) {
//let the cluster know that there is a context that is distributable
//and that it has its own manager
getCluster().registerManager(manager);
}
}
if (!getConfigured()) {
log.error(sm.getString("standardContext.configurationFail"));
ok = false;
}
// We put the resources into the servlet context
if (ok)
getServletContext().setAttribute
(Globals.RESOURCES_ATTR, getResources());
if (ok ) {
if (getInstanceManager() == null) {
javax.naming.Context context = null;
if (isUseNaming() && getNamingContextListener() != null) {
context = getNamingContextListener().getEnvContext();
}
Map<String, Map<String, String>> injectionMap = buildInjectionMap(
getIgnoreAnnotations() ? new NamingResourcesImpl(): getNamingResources());
setInstanceManager(new DefaultInstanceManager(context,
injectionMap, this, this.getClass().getClassLoader()));
}
getServletContext().setAttribute(
InstanceManager.class.getName(), getInstanceManager());
InstanceManagerBindings.bind(getLoader().getClassLoader(), getInstanceManager());
}
// Create context attributes that will be required
if (ok) {
getServletContext().setAttribute(
JarScanner.class.getName(), getJarScanner());
}
// Set up the context init params
mergeParameters();
// Call ServletContainerInitializers
for (Map.Entry<ServletContainerInitializer, Set<Class<?>>> entry :
initializers.entrySet()) {
try {
entry.getKey().onStartup(entry.getValue(),
getServletContext());
} catch (ServletException e) {
log.error(sm.getString("standardContext.sciFail"), e);
ok = false;
break;
}
}
// Configure and call application event listeners
if (ok) {
if (!listenerStart()) {
log.error(sm.getString("standardContext.listenerFail"));
ok = false;
}
}
// Check constraints for uncovered HTTP methods
// Needs to be after SCIs and listeners as they may programmatically
// change constraints
if (ok) {
checkConstraintsForUncoveredMethods(findConstraints());
}
try {
// Start manager
Manager manager = getManager();
if (manager instanceof Lifecycle) {
((Lifecycle) manager).start();
}
} catch(Exception e) {
log.error(sm.getString("standardContext.managerFail"), e);
ok = false;
}
// Configure and call application filters
if (ok) {
if (!filterStart()) {
log.error(sm.getString("standardContext.filterFail"));
ok = false;
}
}
// Load and initialize all "load on startup" servlets
if (ok) {
if (!loadOnStartup(findChildren())){
log.error(sm.getString("standardContext.servletFail"));
ok = false;
}
}
// Start ContainerBackgroundProcessor thread
super.threadStart();
} finally {
// Unbinding thread
unbindThread(oldCCL);
}
// Set available status depending upon startup success
if (ok) {
if (log.isDebugEnabled())
log.debug("Starting completed");
} else {
log.error(sm.getString("standardContext.startFailed", getName()));
}
startTime=System.currentTimeMillis();
// Send j2ee.state.running notification
if (ok && (this.getObjectName() != null)) {
Notification notification =
new Notification("j2ee.state.running", this.getObjectName(),
sequenceNumber.getAndIncrement());
broadcaster.sendNotification(notification);
}
// The WebResources implementation caches references to JAR files. On
// some platforms these references may lock the JAR files. Since web
// application start is likely to have read from lots of JARs, trigger
// a clean-up now.
getResources().gc();
// Reinitializing if something went wrong
if (!ok) {
setState(LifecycleState.FAILED);
} else {
setState(LifecycleState.STARTING);
}
}第二步：本方法不会进行web.xml文件的解析工作，而是再次委托给LifecycleListener接口的实现类处理。这里LifecycleListener接口的实现类是ContextConfig类文章源自JAVA秀-https://www.javaxiu.com/19939.html
protected void fireLifecycleEvent(String type, Object data) {
LifecycleEvent event = new LifecycleEvent(this, type, data);
for (LifecycleListener listener : lifecycleListeners) {
//再次委托给ContextConfig类的lifecycleEvent方法解析web.xml文件
listener.lifecycleEvent(event);
}
}第三步：本方法不会进行web.xml文件的解析工作，而是再次委托给configureStart方法继续处理文章源自JAVA秀-https://www.javaxiu.com/19939.html
@Override
public void lifecycleEvent(LifecycleEvent event) {
// Identify the context we are associated with
try {
context = (Context) event.getLifecycle();
} catch (ClassCastException e) {
log.error(sm.getString("contextConfig.cce", event.getLifecycle()), e);
return;
}
// Process the event that has occurred
if (event.getType().equals(Lifecycle.CONFIGURE_START_EVENT)) {
//再次委托给configureStart方法继续处理
configureStart();
} else if (event.getType().equals(Lifecycle.BEFORE_START_EVENT)) {
beforeStart();
} else if (event.getType().equals(Lifecycle.AFTER_START_EVENT)) {
// Restore docBase for management tools
if (originalDocBase != null) {
context.setDocBase(originalDocBase);
}
} else if (event.getType().equals(Lifecycle.CONFIGURE_STOP_EVENT)) {
configureStop();
} else if (event.getType().equals(Lifecycle.AFTER_INIT_EVENT)) {
init();
} else if (event.getType().equals(Lifecycle.AFTER_DESTROY_EVENT)) {
destroy();
}
}第四步：本方法不会进行web.xml文件的解析工作，而是再次委托给webConfig方法继续处理文章源自JAVA秀-https://www.javaxiu.com/19939.html
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())));
}
//再次委托给webConfig方法继续处理
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);
}
}第五步：本方法不会进行web.xml文件详细解析工作，但是是一个重要的模板方法。这个方法完成，基本上也就完成了将web.xml文件信息提取解析到ServletContext对象的操作文章源自JAVA秀-https://www.javaxiu.com/19939.html
protected void webConfig() {
WebXmlParser webXmlParser = new WebXmlParser(context.getXmlNamespaceAware(),
context.getXmlValidation(), context.getXmlBlockExternal());
Set<WebXml> defaults = new HashSet<>();
defaults.add(getDefaultWebXmlFragment(webXmlParser));
Set<WebXml> tomcatWebXml = new HashSet<>();
tomcatWebXml.add(getTomcatWebXmlFragment(webXmlParser));
//创建一个空WebXml对象，里面暂时不包含任何信息
WebXml webXml = createWebXml();
//将web.xml文件抽象（转换）为一个contextWebXml实例（InputSource对象），此时的contextWebXml实例就是web.xml文件的最新的信息承载者。
InputSource contextWebXml = getContextWebXmlSource();
//使用webXmlParser对象，将contextWebXml中的信息提取并存储到webXml对象中，此时的webXml对象就是web.xml文件的最新的信息承载者。
if (!webXmlParser.parseWebXml(contextWebXml, webXml, false)) {
ok = false;
}
//从StardardContext对象中获取一个空的ServletContext对象
ServletContext sContext = context.getServletContext();
// Ordering is important here
// 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) {
// Steps 4 & 5.
processClasses(webXml, orderedFragments);
}
if (!webXml.isMetadataComplete()) {
// Step 6. Merge web-fragment.xml files into the main web.xml
// file.
if (ok) {
ok = webXml.merge(orderedFragments);
}
// Step 7a
// merge tomcat-web.xml
webXml.merge(tomcatWebXml);
// Step 7b. 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) {
//将webXml中的信息提取并存储到ServletContext对象中，此时的ServletContext对象就是web.xml文件的最新的信息承载者。这儿也就是下面的第三步。
configureContext(webXml);
}
} else {
webXml.merge(tomcatWebXml);
webXml.merge(defaults);
convertJsps(webXml);
configureContext(webXml);
}
if (context.getLogEffectiveWebXml()) {
log.info(sm.getString("contextConfig.effectiveWebXml", 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());
}
}
}
}
//这个方法里面有一个常量Constants.ApplicationWebXml，我们跳转到这个常量的定义String ApplicationWebXml = "/WEB-INF/web.xml"，从这儿我们基本上确定就是从这儿开始web.xml的解析的
protected InputSource getContextWebXmlSource() {
InputStream stream = null;
InputSource source = null;
URL url = null;
String altDDName = null;
// Open the application web.xml file, if it exists
ServletContext servletContext = context.getServletContext();
try {
if (servletContext != null) {
altDDName = (String)servletContext.getAttribute(Globals.ALT_DD_ATTR);
if (altDDName != null) {
try {
stream = new FileInputStream(altDDName);
url = new File(altDDName).toURI().toURL();
} catch (FileNotFoundException e) {
log.error(sm.getString("contextConfig.altDDNotFound",
altDDName));
} catch (MalformedURLException e) {
log.error(sm.getString("contextConfig.applicationUrl"));
}
}
else {
//此处的Constants.ApplicationWebXml常量就是"web.xml"，从这里我们基本上可以确定了，从这行代码开始，就是web.xml开始被tomcat这个web容器开始解析的开端
stream = servletContext.getResourceAsStream
(Constants.ApplicationWebXml);
try {
url = servletContext.getResource(
Constants.ApplicationWebXml);
} catch (MalformedURLException e) {
log.error(sm.getString("contextConfig.applicationUrl"));
}
}
}
if (stream == null || url == null) {
if (log.isDebugEnabled()) {
log.debug(sm.getString("contextConfig.applicationMissing") + " " + context);
}
} else {
source = new InputSource(url.toExternalForm());
source.setByteStream(stream);
}
} finally {
if (source == null && stream != null) {
try {
stream.close();
} catch (IOException e) {
// Ignore
}
}
}
return source;
}第六步：将WebXml对象中承载的web.xml文件的标签信息，提取出来，并解析到ServletContext对象中，最终完成web.xml文件到ServletContext的解析操作。文章源自JAVA秀-https://www.javaxiu.com/19939.html
private void configureContext(WebXml webxml) {
// As far as possible, process in alphabetical order so it is easy to
// check everything is present
// Some validation depends on correct public ID
context.setPublicId(webxml.getPublicId());
// Everything else in order
context.setEffectiveMajorVersion(webxml.getMajorVersion());
context.setEffectiveMinorVersion(webxml.getMinorVersion());
//context-param标签信息的解析
for (Entry<String, String> entry : webxml.getContextParams().entrySet()) {
context.addParameter(entry.getKey(), entry.getValue());
}
context.setDenyUncoveredHttpMethods(
webxml.getDenyUncoveredHttpMethods());
context.setDisplayName(webxml.getDisplayName());
context.setDistributable(webxml.isDistributable());
for (ContextLocalEjb ejbLocalRef : webxml.getEjbLocalRefs().values()) {
context.getNamingResources().addLocalEjb(ejbLocalRef);
}
for (ContextEjb ejbRef : webxml.getEjbRefs().values()) {
context.getNamingResources().addEjb(ejbRef);
}
for (ContextEnvironment environment : webxml.getEnvEntries().values()) {
context.getNamingResources().addEnvironment(environment);
}
for (ErrorPage errorPage : webxml.getErrorPages().values()) {
context.addErrorPage(errorPage);
}
//过滤器标签信息的解析
for (FilterDef filter : webxml.getFilters().values()) {
if (filter.getAsyncSupported() == null) {
filter.setAsyncSupported("false");
}
context.addFilterDef(filter);
}
for (FilterMap filterMap : webxml.getFilterMappings()) {
context.addFilterMap(filterMap);
}
//监听器标签信息的解析
context.setJspConfigDescriptor(webxml.getJspConfigDescriptor());
for (String listener : webxml.getListeners()) {
context.addApplicationListener(listener);
}
for (Entry<String, String> entry :
webxml.getLocaleEncodingMappings().entrySet()) {
context.addLocaleEncodingMappingParameter(entry.getKey(),
entry.getValue());
}
// Prevents IAE
if (webxml.getLoginConfig() != null) {
context.setLoginConfig(webxml.getLoginConfig());
}
for (MessageDestinationRef mdr :
webxml.getMessageDestinationRefs().values()) {
context.getNamingResources().addMessageDestinationRef(mdr);
}
// messageDestinations were ignored in Tomcat 6, so ignore here
context.setIgnoreAnnotations(webxml.isMetadataComplete());
for (Entry<String, String> entry :
webxml.getMimeMappings().entrySet()) {
context.addMimeMapping(entry.getKey(), entry.getValue());
}
context.setRequestCharacterEncoding(webxml.getRequestCharacterEncoding());
// Name is just used for ordering
for (ContextResourceEnvRef resource :
webxml.getResourceEnvRefs().values()) {
context.getNamingResources().addResourceEnvRef(resource);
}
for (ContextResource resource : webxml.getResourceRefs().values()) {
context.getNamingResources().addResource(resource);
}
context.setResponseCharacterEncoding(webxml.getResponseCharacterEncoding());
boolean allAuthenticatedUsersIsAppRole =
webxml.getSecurityRoles().contains(
SecurityConstraint.ROLE_ALL_AUTHENTICATED_USERS);
for (SecurityConstraint constraint : webxml.getSecurityConstraints()) {
if (allAuthenticatedUsersIsAppRole) {
constraint.treatAllAuthenticatedUsersAsApplicationRole();
}
context.addConstraint(constraint);
}
for (String role : webxml.getSecurityRoles()) {
context.addSecurityRole(role);
}
for (ContextService service : webxml.getServiceRefs().values()) {
context.getNamingResources().addService(service);
}
//Servlet标签信息的解析
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());
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());
}
}
// Context doesn't use version directly
for (String welcomeFile : webxml.getWelcomeFiles()) {
/*
* The following will result in a welcome file of "" so don't add
* that to the context
* <welcome-file-list>
* <welcome-file/>
* </welcome-file-list>
*/
if (welcomeFile != null && welcomeFile.length() > 0) {
context.addWelcomeFile(welcomeFile);
}
}
// Do this last as it depends on servlets
for (JspPropertyGroup jspPropertyGroup :
webxml.getJspPropertyGroups()) {
String jspServletName = context.findServletMapping("*.jsp");
if (jspServletName == null) {
jspServletName = "jsp";
}
if (context.findChild(jspServletName) != null) {
for (String urlPattern : jspPropertyGroup.getUrlPatterns()) {
context.addServletMappingDecoded(urlPattern, jspServletName, true);
}
} else {
if(log.isDebugEnabled()) {
for (String urlPattern : jspPropertyGroup.getUrlPatterns()) {
log.debug("Skipping " + urlPattern + " , no servlet " +
jspServletName);
}
}
}
}
for (Entry<String, String> entry :
webxml.getPostConstructMethods().entrySet()) {
context.addPostConstructMethod(entry.getKey(), entry.getValue());
}
for (Entry<String, String> entry :
webxml.getPreDestroyMethods().entrySet()) {
context.addPreDestroyMethod(entry.getKey(), entry.getValue());
}
}说明：怎么样测试第六步的configureContext方法，的确完成了web.xml文件的解析呢？我们在前面一篇文章说过，当web.xml文件北解析完成，那么ServletContext对象中能拿到web.xml中配置的过滤器对象，Servlet对象等等信息。那么我们结合下面的三张图基本上就可以确定了。文章源自JAVA秀-https://www.javaxiu.com/19939.html
首先我们在第五步的configureContext(webXml)行代码处打断点如下：文章源自JAVA秀-https://www.javaxiu.com/19939.html
文章源自JAVA秀-https://www.javaxiu.com/19939.html
其次我们使用idea的注入Evaluate功能，查询ServletContext对象中是否持有过滤器对象，结果是没有。文章源自JAVA秀-https://www.javaxiu.com/19939.html
文章源自JAVA秀-https://www.javaxiu.com/19939.html
最后我们继续运行代码，完成configureContext(webXml)代码的执行，将断点断在下面一行，我们再次使用idea的注入Evaluate功能，查询ServletContext对象中是否持有过滤器对象，我们发现ServletContext对象已经持有了过滤器对象了。文章源自JAVA秀-https://www.javaxiu.com/19939.html
文章源自JAVA秀-https://www.javaxiu.com/19939.html
说明到这一步，也就基本上完成了web.xml文件的大部分的一些解析的工作了。文章源自JAVA秀-https://www.javaxiu.com/19939.html
文章源自JAVA秀-https://www.javaxiu.com/19939.html
更多知识请关注公众号文章源自JAVA秀-https://www.javaxiu.com/19939.html
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