struts2源码分析--请求流程
??????? if (configurationManager == null) {
??????????? configurationManager = new ConfigurationManager(BeanSelectionProvider.DEFAULT_BEAN_NAME);
??????? }
??????? init_DefaultProperties(); // [1]
??????? init_TraditionalXmlConfigurations(); // [2]
??????? init_LegacyStrutsProperties(); // [3]
??????? init_ZeroConfiguration(); // [4]
??????? init_CustomConfigurationProviders(); // [5]
??????? init_MethodConfigurationProvider();
??????? init_FilterInitParameters() ; // [6]
??????? init_AliasStandardObjects() ; // [7]
??????? Container container = init_PreloadConfiguration();
??????? init_CheckConfigurationReloading(container);
??????? init_CheckWebLogicWorkaround(container);
??? }
??? private void init_DefaultProperties() {
??????? configurationManager.addConfigurationProvider(new DefaultPropertiesProvider());
??? }
??? //DefaultPropertiesProvider
??? public void register(ContainerBuilder builder, LocatableProperties props)
??????????? throws ConfigurationException {
????????
??????? Settings defaultSettings = null;
??????? try {
??????????? defaultSettings = new PropertiesSettings("org/apache/struts2/default");
??????? } catch (Exception e) {
??????????? throw new ConfigurationException("Could not find or error in org/apache/struts2/default.properties", e);
??????? }
????????
??????? loadSettings(props, defaultSettings);
??? }
??? //PropertiesSettings
??? //读取org/apache/struts2/default.properties的配置信息，如果项目中需要覆盖，可以在classpath里的struts.properties里覆写
??? public PropertiesSettings(String name) {
????????
??????? URL settingsUrl = ClassLoaderUtils.getResource(name + ".properties", getClass());
????????
??????? if (settingsUrl == null) {
??????????? LOG.debug(name + ".properties missing");
??????????? settings = new LocatableProperties();
??????????? return;
??????? }
??????? //settings的类型为LocatableProperties，继承Properties
??????? settings = new LocatableProperties(new LocationImpl(null, settingsUrl.toString()));
??????? // Load settings
??????? InputStream in = null;
??????? try {
??????????? in = settingsUrl.openStream();
??????????? settings.load(in);
??????? } catch (IOException e) {
??????????? throw new StrutsException("Could not load " + name + ".properties:" + e, e);
??????? } finally {
??????????? if(in != null) {
??????????????? try {
??????????????????? in.close();
??????????????? } catch(IOException io) {
??????????????????? LOG.warn("Unable to close input stream", io);
??????????????? }
??????????? }
??????? }
??? }
??? 再来看init_TraditionalXmlConfigurations方法，这个是读取Action配置的方法。
??? private void init_TraditionalXmlConfigurations() {
??????? //首先读取web.xml中的config初始参数值
??????? //如果没有配置就使用默认的"struts-default.xml,struts-plugin.xml,struts.xml"，
??????? //这儿就可以看出为什么默认的配置文件必须取名为这三个名称了
??????? //如果不想使用默认的名称，直接在web.xml中配置config初始参数即可
??????? String configPaths = initParams.get("config");
??????? if (configPaths == null) {
??????????? configPaths = DEFAULT_CONFIGURATION_PATHS;
??????? }
??????? String[] files = configPaths.split("\\s*[,]\\s*");
??????? //依次解析配置文件，xwork.xml单独解析
??????? for (String file : files) {
??????????? if (file.endsWith(".xml")) {
??????????????? if ("xwork.xml".equals(file)) {
??????????????????? configurationManager.addConfigurationProvider(new XmlConfigurationProvider(file, false));
??????????????? } else {
??????????????????? configurationManager.addConfigurationProvider(new StrutsXmlConfigurationProvider(file, false, servletContext));
??????????????? }
??????????? } else {
??????????????? throw new IllegalArgumentException("Invalid configuration file name");
??????????? }
??????? }
??? }
??? 对于其它配置文件只用StrutsXmlConfigurationProvider，此类继承XmlConfigurationProvider，而XmlConfigurationProvider又实现ConfigurationProvider接口。类XmlConfigurationProvider负责配置文件的读取和解析，addAction()方法负责读取<action>标签，并将数据保存在ActionConfig中；addResultTypes()方法负责将<result-type>标签转化为ResultTypeConfig对象；loadInterceptors()方法负责将<interceptor>标签转化为InterceptorConfi对象；loadInterceptorStack()方法负责将<interceptor-ref>标签转化为InterceptorStackConfig对象；loadInterceptorStacks()方法负责将<interceptor-stack>标签转化成InterceptorStackConfig对象。而上面的方法最终会被addPackage()方法调用，将所读取到的数据汇集到PackageConfig对象中。
??? protected PackageConfig addPackage(Element packageElement) throws ConfigurationException {
??????? PackageConfig.Builder newPackage = buildPackageContext(packageElement);
??????? if (newPackage.isNeedsRefresh()) {
??????????? return newPackage.build();
??????? }
??????? if (LOG.isDebugEnabled()) {
??????????? LOG.debug("Loaded " + newPackage);
??????? }
??????? // add result types (and default result) to this package
??????? addResultTypes(newPackage, packageElement);
??????? // load the interceptors and interceptor stacks for this package
??????? loadInterceptors(newPackage, packageElement);
??????? // load the default interceptor reference for this package
??????? loadDefaultInterceptorRef(newPackage, packageElement);
??????? // load the default class ref for this package
??????? loadDefaultClassRef(newPackage, packageElement);
??????? // load the global result list for this package
??????? loadGlobalResults(newPackage, packageElement);
??????? // load the global exception handler list for this package
??????? loadGobalExceptionMappings(newPackage, packageElement);
??????? // get actions
??????? NodeList actionList = packageElement.getElementsByTagName("action");
??????? for (int i = 0; i < actionList.getLength(); i++) {
??????????? Element actionElement = (Element) actionList.item(i);
??????????? addAction(actionElement, newPackage);
??????? }
??????? // load the default action reference for this package
??????? loadDefaultActionRef(newPackage, packageElement);
??????? PackageConfig cfg = newPackage.build();
??????? configuration.addPackageConfig(cfg.getName(), cfg);
??????? return cfg;
??? }
??? 这儿发现一个配置上的小东西，我的xwork2.0.*是没有的，但是看源码是看到xwork2.1.*是可以的。看如下代码：
??? private List loadConfigurationFiles(String fileName, Element includeElement) {
??????? List<Document> docs = new ArrayList<Document>();
??????? if (!includedFileNames.contains(fileName)) {
??????????? ...........
??????????????? Element rootElement = doc.getDocumentElement();
??????????????? NodeList children = rootElement.getChildNodes();
??????????????? int childSize = children.getLength();
??????????????? for (int i = 0; i < childSize; i++) {
??????????????????? Node childNode = children.item(i);
??????????????????? if (childNode instanceof Element) {
??????????????????????? Element child = (Element) childNode;
??????????????????????? final String nodeName = child.getNodeName();
??????????????????????? //解析每个action配置是，对于include文件可以使用通配符*来进行配置
??????????????????????? //如Struts.xml中可配置成<include file="actions_*.xml"/>
??????????????????????? if (nodeName.equals("include")) {
??????????????????????????? String includeFileName = child.getAttribute("file");
??????????????????????????? if(includeFileName.indexOf('*') != -1 ) {
??????????????????????????????? // handleWildCardIncludes(includeFileName, docs, child);
??????????????????????????????? ClassPathFinder wildcardFinder = new ClassPathFinder();
??????????????????????????????? wildcardFinder.setPattern(includeFileName);
??????????????????????????????? Vector<String> wildcardMatches = wildcardFinder.findMatches();
??????????????????????????????? for (String match : wildcardMatches) {
??????????????????????????????????? docs.addAll(loadConfigurationFiles(match, child));
??????????????????????????????? }
??????????????????????????? }
??????????????????????????? else {
????????????????????????????????
??????????????????????????????? docs.addAll(loadConfigurationFiles(includeFileName, child));????
??????????????????????????? }????
??????????????????? }
??????????????? }
??????????????? }
??????????????? docs.add(doc);
??????????????? loadedFileUrls.add(url.toString());
??????????? }
??????? }
??????? return docs;
??? }
??? init_CustomConfigurationProviders方式初始自定义的Provider，配置类全名和实现ConfigurationProvider接口就可以。
??? public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain) throws IOException, ServletException {
??????? HttpServletRequest request = (HttpServletRequest) req;
??????? HttpServletResponse response = (HttpServletResponse) res;
??????? ServletContext servletContext = getServletContext();
??????? String timerKey = "FilterDispatcher_doFilter: ";
??????? try {
??????????? UtilTimerStack.push(timerKey);
??????????? //根据content type来使用不同的Request封装，可以参见Dispatcher的wrapRequest
??????????? request = prepareDispatcherAndWrapRequest(request, response);
??????????? ActionMapping mapping;
??????????? try {
??????????????? //根据url取得对应的Action的配置信息--ActionMapping，actionMapper是通过Container的inject注入的
??????????????? mapping = actionMapper.getMapping(request, dispatcher.getConfigurationManager());
??????????? } catch (Exception ex) {
??????????????? LOG.error("error getting ActionMapping", ex);
??????????????? dispatcher.sendError(request, response, servletContext, HttpServletResponse.SC_INTERNAL_SERVER_ERROR, ex);
??????????????? return;
??????????? }
??????????? //如果找不到对应的action配置，则直接返回。比如你输入***.jsp等等
??????????? //这儿有个例外，就是如果path是以“/struts”开头，则到初始参数packages配置的包路径去查找对应的静态资源并输出到页面流中，当然.class文件除外。如果再没有则跳转到404
????????? if (mapping == null) {
??????????????? // there is no action in this request, should we look for a static resource?
??????????????? String resourcePath = RequestUtils.getServletPath(request);
??????????????? if ("".equals(resourcePath) && null != request.getPathInfo()) {
??????????????????? resourcePath = request.getPathInfo();
??????????????? }
??????????????? if (serveStatic && resourcePath.startsWith("/struts")) {
??????????????????? String name = resourcePath.substring("/struts".length());
??????????????????? findStaticResource(name, request, response);
??????????????? } else {
??????????????????? // this is a normal request, let it pass through
??????????????????? chain.doFilter(request, response);
??????????????? }
??????????????? // The framework did its job here
??????????????? return;
??????????? }
??????????? //正式开始执行Action的方法了
??????????? dispatcher.serviceAction(request, response, servletContext, mapping);
??????? } finally {
??????????? try {
??????????????? ActionContextCleanUp.cleanUp(req);
??????????? } finally {
??????????????? UtilTimerStack.pop(timerKey);
??????????? }
??????? }
??? }
??? 来看Dispatcher类的serviceAction方法：
??? public void serviceAction(HttpServletRequest request, HttpServletResponse response, ServletContext context,
????????????????????????????? ActionMapping mapping) throws ServletException {
??????? Map<String, Object> extraContext = createContextMap(request, response, mapping, context);
??????? // If there was a previous value stack, then create a new copy and pass it in to be used by the new Action
??????? ValueStack stack = (ValueStack) request.getAttribute(ServletActionContext.STRUTS_VALUESTACK_KEY);
??????? if (stack != null) {
??????????? extraContext.put(ActionContext.VALUE_STACK, ValueStackFactory.getFactory().createValueStack(stack));
??????? }
??????? String timerKey = "Handling request from Dispatcher";
??????? try {
??????????? UtilTimerStack.push(timerKey);
??????????? String namespace = mapping.getNamespace();
??????????? String name = mapping.getName();
??????????? String method = mapping.getMethod();
??????????? Configuration config = configurationManager.getConfiguration();
??????????? ActionProxy proxy = config.getContainer().getInstance(ActionProxyFactory.class).createActionProxy(namespace, name, extraContext, true, false);
??????????? proxy.setMethod(method);
??????????? request.setAttribute(ServletActionContext.STRUTS_VALUESTACK_KEY, proxy.getInvocation().getStack());
??????????? // if the ActionMapping says to go straight to a result, do it!
??????????? if (mapping.getResult() != null) {
??????????????? Result result = mapping.getResult();
??????????????? result.execute(proxy.getInvocation());
??????????? } else {
??????????????? proxy.execute();
??????????? }
??????????? // If there was a previous value stack then set it back onto the request
??????????? if (stack != null) {
??????????????? request.setAttribute(ServletActionContext.STRUTS_VALUESTACK_KEY, stack);
??????????? }
??????? } catch (ConfigurationException e) {
??????????? LOG.error("Could not find action or result", e);
??????????? sendError(request, response, context, HttpServletResponse.SC_NOT_FOUND, e);
??????? } catch (Exception e) {
??????????? throw new ServletException(e);
??????? } finally {
??????????? UtilTimerStack.pop(timerKey);
??????? }
??? }
??? 第一句createContextMap()方法，该方法主要把Application、Session、Request的key value值拷贝到Map中，并放在HashMap<String,Object>中，可以参见createContextMap方法：
??? public HashMap<String,Object> createContextMap(Map requestMap,
??????????????????????????????????? Map parameterMap,
??????????????????????????????????? Map sessionMap,
??????????????????????????????????? Map applicationMap,
??????????????????????????????????? HttpServletRequest request,
??????????????????????????????????? HttpServletResponse response,
??????????????????????????????????? ServletContext servletContext) {
??????? HashMap<String,Object> extraContext = new HashMap<String,Object>();
??????? extraContext.put(ActionContext.PARAMETERS, new HashMap(parameterMap));
??????? extraContext.put(ActionContext.SESSION, sessionMap);
??????? extraContext.put(ActionContext.APPLICATION, applicationMap);
??????? Locale locale;
??????? if (defaultLocale != null) {
??????????? locale = LocalizedTextUtil.localeFromString(defaultLocale, request.getLocale());
??????? } else {
??????????? locale = request.getLocale();
??????? }
??????? extraContext.put(ActionContext.LOCALE, locale);
??????? //extraContext.put(ActionContext.DEV_MODE, Boolean.valueOf(devMode));
??????? extraContext.put(StrutsStatics.HTTP_REQUEST, request);
??????? extraContext.put(StrutsStatics.HTTP_RESPONSE, response);
??????? extraContext.put(StrutsStatics.SERVLET_CONTEXT, servletContext);
??????? // helpers to get access to request/session/application scope
??????? extraContext.put("request", requestMap);
??????? extraContext.put("session", sessionMap);
??????? extraContext.put("application", applicationMap);
??????? extraContext.put("parameters", parameterMap);
??????? AttributeMap attrMap = new AttributeMap(extraContext);
??????? extraContext.put("attr", attrMap);
??????? return extraContext;
??? }
??? 后面才是最主要的--ActionProxy，ActionInvocation。ActionProxy是Action的一个代理类，也就是说Action的调用是通过ActionProxy实现的，其实就是调用了ActionProxy.execute()方法，而该方法又调用了ActionInvocation.invoke()方法。归根到底，最后调用的是DefaultActionInvocation.invokeAction()方法。先看DefaultActionInvocation的init方法。
??? public void init(ActionProxy proxy) {
??????? this.proxy = proxy;
??????? Map contextMap = createContextMap();
??????? //设置ActionContext，把ActionInvocation和Action压入ValueStack
??????? ActionContext actionContext = ActionContext.getContext();
??????? if(actionContext != null) {
??????????? actionContext.setActionInvocation(this);
??????? }
??????? //创建Action，可以看出Struts2里是每次请求都新建一个Action，careateAction方法可以自己参考
??????? createAction(contextMap);
??????? if (pushAction) {
??????????? stack.push(action);
??????????? contextMap.put("action", action);
??????? }
??????? invocationContext = new ActionContext(contextMap);
??????? invocationContext.setName(proxy.getActionName());
??????? List interceptorList = new ArrayList(proxy.getConfig().getInterceptors());
??????? interceptors = interceptorList.iterator();
??? }
??? protected void createAction(Map contextMap) {
??????? String timerKey = "actionCreate: "+proxy.getActionName();
??????? try {
??????????? UtilTimerStack.push(timerKey);
??????????? //这儿默认建立Action是StrutsObjectFactory，实际中我使用的时候都是使用Spring创建的Action，这个时候使用的是SpringObjectFactory
??????????? action = objectFactory.buildAction(proxy.getActionName(), proxy.getNamespace(), proxy.getConfig(), contextMap);
??????? }
???????? .......?
???????? catch (Exception e) {
??????????? ........
??????????? throw new XWorkException(gripe, e, proxy.getConfig());
??????? } finally {
??????????? UtilTimerStack.pop(timerKey);
??????? }
??????? if (actionEventListener != null) {
??????????? action = actionEventListener.prepare(action, stack);
??????? }
??? }
??? 接下来看看DefaultActionInvocation 的invoke方法。
??? public String invoke() throws Exception {
??????? String profileKey = "invoke: ";
??????? try {
??????????? UtilTimerStack.push(profileKey);
????????????
??????????? if (executed) {
??????????????? throw new IllegalStateException("Action has already executed");
??????????? }
??????????????? //先执行interceptors
??????????? if (interceptors.hasNext()) {
??????????????? final InterceptorMapping interceptor = (InterceptorMapping) interceptors.next();
??????????????? UtilTimerStack.profile("interceptor: "+interceptor.getName(),?
??????????????????????? new UtilTimerStack.ProfilingBlock<String>() {
??????????????????????????? public String doProfiling() throws Exception {
??????????????????????????????? resultCode = interceptor.getInterceptor().intercept(DefaultActionInvocation.this);
??????????????????????????????? return null;
??????????????????????????? }
??????????????? });
??????????? } else {
??????????????????????? //interceptor执行完了之后执行action
??????????????? resultCode = invokeActionOnly();
??????????? }
??????????? if (!executed) {
??????????????? if (preResultListeners != null) {
??????????????????? for (Iterator iterator = preResultListeners.iterator();
??????????????????????? iterator.hasNext();) {
??????????????????????? PreResultListener listener = (PreResultListener) iterator.next();
????????????????????????
??????????????????????? String _profileKey="preResultListener: ";
??????????????????????? try {
??????????????????????????? UtilTimerStack.push(_profileKey);
??????????????????????????? listener.beforeResult(this, resultCode);
??????????????????????? }
??????????????????????? finally {
??????????????????????????? UtilTimerStack.pop(_profileKey);
??????????????????????? }
??????????????????? }
??????????????? }
??????????????? // now execute the result, if we're supposed to
??????????????? if (proxy.getExecuteResult()) {
??????????????????? executeResult();
??????????????? }
??????????????? executed = true;
??????????? }
??????????? return resultCode;
??????? }
??????? finally {
??????????? UtilTimerStack.pop(profileKey);
??????? }
??? }
???? 看程序中的if(interceptors.hasNext())语句，当然，interceptors里存储的是interceptorMapping列表（它包括一个Interceptor和一个name），所有的截拦器必须实现Interceptor的intercept方法，而该方法的参数恰恰又是ActionInvocation，在intercept方法中还是调用invocation.invoke()，从而实现了一个Interceptor链的调用。当所有的Interceptor执行完，最后调用invokeActionOnly方法来执行Action相应的方法。
??? protected String invokeAction(Object action, ActionConfig actionConfig) throws Exception {
??????? String methodName = proxy.getMethod();
??????? String timerKey = "invokeAction: "+proxy.getActionName();
??????? try {
??????????? UtilTimerStack.push(timerKey);
????????????
??????????? boolean methodCalled = false;
??????????? Object methodResult = null;
??????????? Method method = null;
??????????? try {
??????????????? //获得Action对应的方法
??????????????? method = getAction().getClass().getMethod(methodName, new Class[0]);
??????????? } catch (NoSuchMethodException e) {
??????????????? try {
??????????????????? //如果没有对应的方法，则使用do+Xxxx来再次获得方法
??????????????????? String altMethodName = "do" + methodName.substring(0, 1).toUpperCase() + methodName.substring(1);
??????????????????? method = getAction().getClass().getMethod(altMethodName, new Class[0]);
??????????????? } catch (NoSuchMethodException e1) {
??????????????????? .....
??????????????? }
??????????? }
????????????
??????????? if (!methodCalled) {
??????????????? methodResult = method.invoke(action, new Object[0]);
??????????? }
??????????? //根据不同的Result类型返回不同值
??????????? if (methodResult instanceof Result) {
??????????????? this.explicitResult = (Result) methodResult;
??????????????? return null;
??????????? } else {
??????????????? return (String) methodResult;
??????????? }
??????? }
??????? ....
??????? } finally {
??????????? UtilTimerStack.pop(timerKey);
??????? }
??? }
????? 好了，action执行完了，还要根据ResultConfig返回到view，也就是在invoke方法中调用executeResult方法。
??? private void executeResult() throws Exception {
??????? //根据ResultConfig创建Result
??????? result = createResult();
??????? String timerKey = "executeResult: "+getResultCode();
??????? try {
??????????? UtilTimerStack.push(timerKey);
??????????? if (result != null) {
??????????????? //这儿正式执行:)
??????????????? //可以参考Result的实现，如用了比较多的ServletDispatcherResult,ServletActionRedirectResult,ServletRedirectResult
??????????????? result.execute(this);
??????????? } else if (resultCode != null && !Action.NONE.equals(resultCode)) {
??????????????? throw new ConfigurationException("No result defined for action " + getAction().getClass().getName()?
??????????????????????? + " and result " + getResultCode(), proxy.getConfig());
??????????? } else {
??????????????? if (LOG.isDebugEnabled()) {
??????????????????? LOG.debug("No result returned for action "+getAction().getClass().getName()+" at "+proxy.getConfig().getLocation());
??????????????? }
??????????? }
??????? } finally {
??????????? UtilTimerStack.pop(timerKey);
??????? }
??? }
??? public Result createResult() throws Exception {
??????? if (explicitResult != null) {
??????????? Result ret = explicitResult;
??????????? explicitResult = null;;
??????????? return ret;
??????? }
??????? ActionConfig config = proxy.getConfig();
??????? Map results = config.getResults();
??????? ResultConfig resultConfig = null;
??????? synchronized (config) {
??????????? try {
??????????????? //根据result名称获得ResultConfig，resultCode就是result的name
??????????????? resultConfig = (ResultConfig) results.get(resultCode);
??????????? } catch (NullPointerException e) {
??????????? }
??????????? if (resultConfig == null) {
??????????????? //如果找不到对应name的ResultConfig，则使用name为*的Result
??????????????? resultConfig = (ResultConfig) results.get("*");
??????????? }
??????? }
??????? if (resultConfig != null) {
??????????? try {
??????????????? //参照StrutsObjectFactory的代码
??????????????? Result result = objectFactory.buildResult(resultConfig, invocationContext.getContextMap());
??????????????? return result;
??????????? } catch (Exception e) {
??????????????? LOG.error("There was an exception while instantiating the result of type " + resultConfig.getClassName(), e);
??????????????? throw new XWorkException(e, resultConfig);
??????????? }
??????? } else if (resultCode != null && !Action.NONE.equals(resultCode) && unknownHandler != null) {
??????????? return unknownHandler.handleUnknownResult(invocationContext, proxy.getActionName(), proxy.getConfig(), resultCode);
??????? }
??????? return null;
??? }
??? //StrutsObjectFactory
??? public Result buildResult(ResultConfig resultConfig, Map extraContext) throws Exception {
??????? String resultClassName = resultConfig.getClassName();
??????? if (resultClassName == null)
??????????? return null;
??????? //创建Result，因为Result是有状态的，所以每次请求都新建一个
??????? Object result = buildBean(resultClassName, extraContext);
??????? reflectionProvider.setProperties(resultConfig.getParams(), result, extraContext);
??????? if (result instanceof Result)
??????????? return (Result) result;
??????? throw new ConfigurationException(result.getClass().getName() + " does not implement Result.");
??? }
?
