Struts2源码分析--请求处理（转）
转帖原地址：http://www.blogjava.net/myyate/articles/Struts2_source_java.html
Struts2架构图
?? ? ? ?请求首先通过Filter chain，Filter主要包括ActionContextCleanUp，它主要清理当前线程的ActionContext和Dispatcher；FilterDispatcher主要通过AcionMapper来决定需要调用哪个Action。?? ? ? ?ActionMapper取得了ActionMapping后，在Dispatcher的serviceAction方法里创建ActionProxy，ActionProxy创建ActionInvocation，然后ActionInvocation调用Interceptors，执行Action本身，创建Result并返回，当然，如果要在返回之前做些什么，可以实现PreResultListener。?Struts2部分类介绍这部分从Struts2参考文档中翻译就可以了。ActionMapper?? ? ? ?ActionMapper其实是HttpServletRequest和Action调用请求的一个映射，它屏蔽了Action对于Request等java Servlet类的依赖。Struts2中它的默认实现类是DefaultActionMapper，ActionMapper很大的用处可以根据自己的需要来设计url格式，它自己也有Restful的实现，具体可以参考文档的docs\actionmapper.html。ActionProxy&ActionInvocation?? ? ? ?Action的一个代理，由ActionProxyFactory创建，它本身不包括Action实例，默认实现DefaultActionProxy是由ActionInvocation持有Action实例。ActionProxy作用是如何取得Action，无论是本地还是远程。而ActionInvocation的作用是如何执行Action，拦截器的功能就是在ActionInvocation中实现的。ConfigurationProvider&Configuration?? ? ? ?ConfigurationProvider就是Struts2中配置文件的解析器，Struts2中的配置文件主要是尤其实现类XmlConfigurationProvider及其子类StrutsXmlConfigurationProvider来解析，?Struts2请求流程1、客户端发送请求2、请求先通过ActionContextCleanUp-->FilterDispatcher3、FilterDispatcher通过ActionMapper来决定这个Request需要调用哪个Action4、如果ActionMapper决定调用某个Action，FilterDispatcher把请求的处理交给ActionProxy，这儿已经转到它的Delegate--Dispatcher来执行5、ActionProxy根据ActionMapping和ConfigurationManager找到需要调用的Action类6、ActionProxy创建一个ActionInvocation的实例7、ActionInvocation调用真正的Action，当然这涉及到相关拦截器的调用8、Action执行完毕，ActionInvocation创建Result并返回，当然，如果要在返回之前做些什么，可以实现PreResultListener。添加PreResultListener可以在Interceptor中实现，不知道其它还有什么方式？?Struts2(2.1.2)部分源码阅读?? ?从org.apache.struts2.dispatcher.FilterDispatcher开始?? ?//创—ispatcher，此类是一个Delegate，它是真正完成根据url解析，读取对应Action的地方????public?void?init(FilterConfig?filterConfig)?throws?ServletException?{
????????try?{
????????????this.filterConfig?=?filterConfig;
????????????initLogging();
????????????dispatcher?=?createDispatcher(filterConfig);
????????????dispatcher.init();
????????????dispatcher.getContainer().inject(this);
????????????//读取初始参数pakages，调用parse()，解析成类似/org/apache/struts2/static,/template的数组
????????????String?param?=?filterConfig.getInitParameter("packages");
????????????String?packages?=?"org.apache.struts2.static?template?org.apache.struts2.interceptor.debugging";
????????????if?(param?!=?null)?{
????????????????packages?=?param?+?"?"?+?packages;
????????????}
????????????this.pathPrefixes?=?parse(packages);
????????}?finally?{
????????????ActionContext.setContext(null);
????????}
????}?? ??顺着流程我们看Disptcher的init方法。init方法里就是初始读取一些配置文件等，先看init_DefaultProperties，主要是读取properties配置文件。?? ?private?void?init_DefaultProperties()?{
????????configurationManager.addConfigurationProvider(new?DefaultPropertiesProvider());
????}?? ?打开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?=?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struts-default.xml和Struts.xml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。来看XmlConfigurationProvider的源代码，详细的我自己也就大体浏览了一下，各位可以自己研读。?? ?protected?PackageConfig?addPackage(Element?packageElement)?throws?ConfigurationException?{
????????PackageConfig.Builder?newPackage?=?buildPackageContext(packageElement);
????????if?(newPackage.isNeedsRefresh())?{
????????????return?newPackage.build();
????????}
????????
.????????addResultTypes(newPackage,?packageElement);
????????loadInterceptors(newPackage,?packageElement);
????????loadDefaultInterceptorRef(newPackage,?packageElement);
????????loadDefaultClassRef(newPackage,?packageElement);
????????loadGlobalResults(newPackage,?packageElement);
????????loadGobalExceptionMappings(newPackage,?packageElement);
????????NodeList?actionList?=?packageElement.getElementsByTagName("action");
????????for?(int?i?=?0;?i?<?actionList.getLength();?i++)?{
????????????Element?actionElement?=?(Element)?actionList.item(i);
????????????addAction(actionElement,?newPackage);
????????}
????????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技巧，我的xwork2.0.*是没有的，但是看源码是看到xwork2.1.*是可以的。继续看XmlConfigurationProvider的源代码：?? ?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?)?{
????????????????????????????????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，用逗号隔开即可。?? ?private?void?init_CustomConfigurationProviders()?{
????????String?configProvs?=?initParams.get("configProviders");
????????if?(configProvs?!=?null)?{
????????????String[]?classes?=?configProvs.split("\\s*[,]\\s*");
????????????for?(String?cname?:?classes)?{
????????????????try?{
????????????????????Class?cls?=?ClassLoaderUtils.loadClass(cname,?this.getClass());
????????????????????ConfigurationProvider?prov?=?(ConfigurationProvider)cls.newInstance();
????????????????????configurationManager.addConfigurationProvider(prov);
????????????????}
????????????????
????????????}
????????}
????}?? ?好了，现在再回到FilterDispatcher，每次发送一个Request，FilterDispatcher都会调用doFilter方法。?? ?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?{
????????????ValueStack?stack?=?dispatcher.getContainer().getInstance(ValueStackFactory.class).createValueStack();
????????????ActionContext?ctx?=?new?ActionContext(stack.getContext());
????????????ActionContext.setContext(ctx);
????????????
????????????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?{
????????????????????chain.doFilter(request,?response);
????????????????}
????????????????return;
????????????}
????????????//正式开始Action的方法了
????????????dispatcher.serviceAction(request,?response,?servletContext,?mapping);
????????}?finally?{
????????????try?{
????????????????ActionContextCleanUp.cleanUp(req);
????????????}?finally?{
????????????????UtilTimerStack.pop(timerKey);
????????????}
????????}
????}?? ?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.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,?method,?extraContext,?true,?false);
????????????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)?{
????????????sendError(request,?response,?context,?HttpServletResponse.SC_INTERNAL_SERVER_ERROR,?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?Map<String,Object>?createContextMap(HttpServletRequest?request,?HttpServletResponse?response,
????????????ActionMapping?mapping,?ServletContext?context)?{
????????//?request?map?wrapping?the?http?request?objects
????????Map?requestMap?=?new?RequestMap(request);
????????//?parameters?map?wrapping?the?http?parameters.??ActionMapping?parameters?are?now?handled?and?applied?separately
????????Map?params?=?new?HashMap(request.getParameterMap());
????????//?session?map?wrapping?the?http?session
????????Map?session?=?new?SessionMap(request);
????????//?application?map?wrapping?the?ServletContext
????????Map?application?=?new?ApplicationMap(context);
????????Map<String,Object>?extraContext?=?createContextMap(requestMap,?params,?session,?application,?request,?response,?context);
????????extraContext.put(ServletActionContext.ACTION_MAPPING,?mapping);
????????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();
????????//?Setting?this?so?that?other?classes,?like?object?factories,?can?use?the?ActionProxy?and?other
????????//?contextual?information?to?operate
????????ActionContext?actionContext?=?ActionContext.getContext();
????????if(actionContext?!=?null)?{
????????????actionContext.setActionInvocation(this);
????????}
????????//创建Action，可Struts2里是每次请求都新建一个Action
????????createAction(contextMap);
????????if?(pushAction)?{
????????????stack.push(action);
????????????contextMap.put("action",?action);
????????}
????????invocationContext?=?new?ActionContext(contextMap);
????????invocationContext.setName(proxy.getActionName());
????????//?get?a?new?List?so?we?don't?get?problems?with?the?iterator?if?someone?changes?the?list
????????List?interceptorList?=?new?ArrayList(proxy.getConfig().getInterceptors());
????????interceptors?=?interceptorList.iterator();
????}
????protected?void?createAction(Map?contextMap)?{
????????//?load?action
????????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);
????????}?
????????
..????????}?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();
????????????}
????????????//?this?is?needed?because?the?result?will?be?executed,?then?control?will?return?to?the?Interceptor,?which?will
????????????//?return?above?and?flow?through?again
????????????if?(!executed)?{
????????????????????????//在Result返回之前调用preResultListeners
????????????????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?{
????????????????//获得需要执行的方法
????????????????method?=?getAction().getClass().getMethod(methodName,?new?Class[0]);
????????????}?catch?(NoSuchMethodException?e)?{
????????????????//如果没有对应的方法，则使用do+Xxxx来再次获得方法
????????????????try?{
????????????????????String?altMethodName?=?"do"?+?methodName.substring(0,?1).toUpperCase()?+?methodName.substring(1);
????????????????????method?=?getAction().getClass().getMethod(altMethodName,?new?Class[0]);
????????????????}?catch?(NoSuchMethodException?e1)?{
????????????????????//?well,?give?the?unknown?handler?a?shot
????????????????????if?(unknownHandler?!=?null)?{
????????????????????????try?{
????????????????????????????methodResult?=?unknownHandler.handleUnknownActionMethod(action,?methodName);
????????????????????????????methodCalled?=?true;
????????????????????????}?catch?(NoSuchMethodException?e2)?{
????????????????????????????//?throw?the?original?one
????????????????????????????throw?e;
????????????????????????}
????????????????????}?else?{
????????????????????????throw?e;
????????????????????}
????????????????}
????????????}
????????????
????????????if?(!methodCalled)?{
????????????????methodResult?=?method.invoke(action,?new?Object[0]);
????????????}
????????????//根据不同的Result类型返回不同值
????????????//如输出流Result
????????????if?(methodResult?instanceof?Result)?{
????????????????this.explicitResult?=?(Result)?methodResult;
????????????????return?null;
????????????}?else?{
????????????????return?(String)?methodResult;
????????????}
????????}?catch?(NoSuchMethodException?e)?{
????????????throw?new?IllegalArgumentException("The?"?+?methodName?+?"()?is?not?defined?in?action?"?+?getAction().getClass()?+?"");
????????}?catch?(InvocationTargetException?e)?{
????????????//?We?try?to?return?the?source?exception.
????????????Throwable?t?=?e.getTargetException();
????????????if?(actionEventListener?!=?null)?{
????????????????String?result?=?actionEventListener.handleException(t,?getStack());
????????????????if?(result?!=?null)?{
????????????????????return?result;
????????????????}
????????????}
????????????if?(t?instanceof?Exception)?{
????????????????throw(Exception)?t;
????????????}?else?{
????????????????throw?e;
????????????}
????????}?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);
????????//这句很重要，后面将会谈到，reflectionProvider参见OgnlReflectionProvider；
????????//resultConfig.getParams()就是result配置文件里所配置的参数<param>
</param>????????//setProperties方法最终调用的是Ognl类的setValue方法
????????//这句其实就是把param名值设置到根对象result上
????????reflectionProvider.setProperties(resultConfig.getParams(),?result,?extraContext);
????????if?(result?instanceof?Result)
????????????return?(Result)?result;
????????throw?new?ConfigurationException(result.getClass().getName()?+?"?does?not?implement?Result.");
????}?? ?最后补充一下，Struts2的查找值和设置值都是使用Ognl来实现的。关于Ognl的介绍可以到其官方网站查看http://www.ognl.org/，我在网上也找到另外一篇http://www.javaeye.com/topic/254684和http://www.javaeye.com/topic/223612。完了来看下面这段小测试程序（其它的Ognl的测试可以自己添加）。public?class?TestOgnl?{
????
????private?User?user;
????private?Map?context;
????
????@Before
????public?void?setUp()?throws?Exception?{
????
????}
????@Test
????public?void?ognlGetValue()?throws?Exception?{
????reset();
????Assert.assertEquals("myyate",?Ognl.getValue("name",?user));
????Assert.assertEquals("cares",?Ognl.getValue("dept.name",?user));
????Assert.assertEquals("myyate",?Ognl.getValue("name",?context,?user));
????Assert.assertEquals("contextmap",?Ognl.getValue("#name",?context,?user));
????Assert.assertEquals("parker",?Ognl.getValue("#pen",?context,?user));
????}
????
????@Test
????public?void?ognlSetValue()?throws?Exception?{
????reset();
????Ognl.setValue("name",?user,?"myyateC");
????Assert.assertEquals("myyateC",?Ognl.getValue("name",?user));
????
????Ognl.setValue("dept.name",?user,?"caresC");
????Assert.assertEquals("caresC",?Ognl.getValue("dept.name",?user));
????
????Assert.assertEquals("contextmap",?Ognl.getValue("#name",?context,?user));
????Ognl.setValue("#name",?context,?user,?"contextmapC");
????Assert.assertEquals("contextmapC",?Ognl.getValue("#name",?context,?user));
????
????Assert.assertEquals("parker",?Ognl.getValue("#pen",?context,?user));
????Ognl.setValue("#name",?context,?user,?"parkerC");
????Assert.assertEquals("parkerC",?Ognl.getValue("#name",?context,?user));
????}
????
????public?static?void?main(String[]?args)?throws?Exception?{
????JUnitCore.runClasses(TestOgnl.class);
????}
????
????private?void?reset()?{
????user?=?new?User("myyate",?new?Dept("cares"));
????context?=?new?OgnlContext();
????context.put("pen",?"parker");
????context.put("name",?"contextmap");
????}
}
class?User?{
????public?User(String?name,?Dept?dept)?{
????this.name?=?name;
????this.dept?=?dept;
????}
????String?name;
????private?Dept?dept;
????public?Dept?getDept()?{
????????return?dept;
????}
????public?String?getName()?{
????????return?name;
????}
????public?void?setDept(Dept?dept)?{
????????this.dept?=?dept;
????}
????public?void?setName(String?name)?{
????????this.name?=?name;
????}
}
class?Dept?{
????public?Dept(String?name)?{
????this.name?=?name;
????}
????private?String?name;
????public?String?getName()?{
????????return?name;
????}
????public?void?setName(String?name)?{
????????this.name?=?name;
????}
}?? ?这样，一个Struts2的请求流程基本上就结束了。其实我觉得做项目把Struts2参考文档看两遍就可以了，呵呵！（写博客比看代码还累）
?