本文剖析的源码波及三个方面：
1 struts中应用到的动静代理：ActionProxy 和 ActionInvocation
2 struts中是如何解决拦截器和action申请的
3 struts中是如何处理结果的
每个申请都会通过Dispatcher中的serviceAction办法，这个办法中有很重要的一句代码
String namespace = mapping.getNamespace();String name = mapping.getName();String method = mapping.getMethod();//步骤1 ActionProxy proxy = 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!// 前面再剖析resultif (mapping.getResult() != null) { Result result = mapping.getResult(); result.execute(proxy.getInvocation());} else { // 步骤2 proxy.execute();}这外面比拟重要的一句是获取proxy的这一句，从container中先获取一个ActionProxyFactory的实例，而后依据命名空间（struts.xml的package？），action的名字，办法名，上下文生成一个ActionProxy，理论是ActionProxy执行了action。
ActionProxyFactory如何创立ActionProxy?
ActionProxyFactory是一个接口，默认的工厂类是DefaultActionProxyFactory，其中的createActionProxy办法如下：
public ActionProxy createActionProxy(String namespace, String actionName, String methodName, Map<String, Object> extraContext, boolean executeResult, boolean cleanupContext) { // 创立了一个ActionInvocation实例 ActionInvocation inv = createActionInvocation(extraContext, true); container.inject(inv); // 通过上面的createActionProxy可知ActionProxy中持有了对ActionInvocation的援用 return createActionProxy(inv, namespace, actionName, methodName, executeResult, cleanupContext);} protected ActionInvocation createActionInvocation(Map<String, Object> extraContext, boolean pushAction) { return new DefaultActionInvocation(extraContext, pushAction);} public ActionProxy createActionProxy(ActionInvocation inv, String namespace, String actionName, String methodName, boolean executeResult, boolean cleanupContext) { // 传进去的inv会在prepare的时候用到 DefaultActionProxy proxy = new DefaultActionProxy(inv, namespace, actionName, methodName, executeResult, cleanupContext); container.inject(proxy); // 有一些初始化操作，比方methodname是null的时候就默认执行execute办法 proxy.prepare(); return proxy;}在下面的proxy.prepare 中，除了会对methodname有解决，还有重要的一步是invocation.init(this)，这里的invocation就是new DefaultActionProxy的时候传入的inv，上面看看DefaultActionInvocation中的init会做些什么
public void init(ActionProxy proxy) { // 可见actionInvocation中也持有一个actionProxy的援用 this.proxy = proxy; Map<String, Object> 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也有一个对actioninvocation的援用 actionContext.setActionInvocation(this); } // 创立action实例 createAction(contextMap); if (pushAction) { stack.push(action); contextMap.put("action", action); } invocationContext = new ActionContext(contextMap); invocationContext.setName(proxy.getActionName()); //创立相干拦截器 createInterceptors(proxy);} //具体看下actioninvocation是如何创立一个action的protected void createAction(Map<String, Object> contextMap) { // load action String timerKey = "actionCreate: " + proxy.getActionName(); try { UtilTimerStack.push(timerKey); // actioninvocation中有一个action的全局变量 // 次要就是这一句，这里用到了objectfactory，这个工厂类持有对actionfactory的援用，理论是调用了actionfactory的buildaction // todo actionfactory的buildaction 前面再具体看actionfactory action = objectFactory.buildAction(proxy.getActionName(), proxy.getNamespace(), proxy.getConfig(), contextMap); } catch (InstantiationException e) { throw new XWorkException("Unable to intantiate Action!", e, proxy.getConfig()); } catch (IllegalAccessException e) { throw new XWorkException("Illegal access to constructor, is it public?", e, proxy.getConfig()); } catch (Exception e) { String gripe; if (proxy == null) { gripe = "Whoa! No ActionProxy instance found in current ActionInvocation. This is bad ... very bad"; } else if (proxy.getConfig() == null) { gripe = "Sheesh. Where'd that ActionProxy get to? I can't find it in the current ActionInvocation!?"; } else if (proxy.getConfig().getClassName() == null) { gripe = "No Action defined for '" + proxy.getActionName() + "' in namespace '" + proxy.getNamespace() + "'"; } else { gripe = "Unable to instantiate Action, " + proxy.getConfig().getClassName() + ", defined for '" + proxy.getActionName() + "' in namespace '" + proxy.getNamespace() + "'"; } gripe += (((" -- " + e.getMessage()) != null) ? e.getMessage() : " [no message in exception]"); throw new XWorkException(gripe, e, proxy.getConfig()); } finally { UtilTimerStack.pop(timerKey); } if (actionEventListener != null) { action = actionEventListener.prepare(action, stack); }} //创立拦截器就比较简单了，依据配置文件把所有的拦截器放在一个list中protected void createInterceptors(ActionProxy proxy) { // get a new List so we don't get problems with the iterator if someone changes the list List<InterceptorMapping> interceptorList = new ArrayList<InterceptorMapping>(proxy.getConfig().getInterceptors()); interceptors = interceptorList.iterator();}理一下后面的：
dispatcher中先创立了actionproxy，同时会创立一个actioninvocation，而后对methodname对解决，创立action实例，创立拦截器list。
到目前为止，dispatcher中的步骤1 实现。当初开始步骤2，步骤2就是具体的要执行action的execute办法。
DefaultActionProxy的execute代码如下
public String execute() throws Exception { //context 相干后续剖析 ActionContext nestedContext = ActionContext.getContext(); ActionContext.setContext(invocation.getInvocationContext()); String retCode = null; String profileKey = "execute: "; try { UtilTimerStack.push(profileKey); // proxy中应用invocation实现action的执行，和java的动静代理是一样的 retCode = invocation.invoke(); } finally { if (cleanupContext) { ActionContext.setContext(nestedContext); } UtilTimerStack.pop(profileKey); } return retCode;}接着看看DefaultActionInvocation的invoke做了什么：
public String invoke() throws Exception { String profileKey = "invoke: "; try { UtilTimerStack.push(profileKey); if (executed) { throw new IllegalStateException("Action has already executed"); } // 这里的interceptors 类型是Iterator<InterceptorMapping>，就是下面createInterceptors的时候被赋值的 // 遍历interceptors if (interceptors.hasNext()) { final InterceptorMapping interceptor = interceptors.next(); String interceptorMsg = "interceptor: " + interceptor.getName(); UtilTimerStack.push(interceptorMsg); try { // 每拿到一个拦截器，就执行拦截器的intercept办法，在拦截器的intercept办法中肯定会执行incovation.invoke，就会又调到本办法中 // 联合这里，就可能晓得拦截器的执行程序，每个拦截器执行到invocation.invoke之后都会递归的调到下一个拦截器上 // 假如有三个拦截器A B C，把每个拦截器在invocation.invoke前的代码成为invoke前，之后的代码成为invoke后 // 执行程序就是：A的invoke前，B的invoke前，c的invoke前，action，c的invoke后，B的invoke后，A的invoke后 resultCode = interceptor.getInterceptor().intercept(DefaultActionInvocation.this); } finally { UtilTimerStack.pop(interceptorMsg); } } else { // 拦截器链中最初一个拦截器的invation.invoke就会执行action自身 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) { if (preResultListeners != null) { LOG.trace("Executing PreResultListeners for result [#0]", result); for (Object preResultListener : preResultListeners) { PreResultListener listener = (PreResultListener) preResultListener; 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); }} public String invokeActionOnly() throws Exception { // 这里的getaction办法就是invocation持有的action实例，即在后面创立action实例的时候创立的 return invokeAction(getAction(), proxy.getConfig());}上面看一下invokeAction办法中是怎么执行action的：
protected String invokeAction(Object action, ActionConfig actionConfig) throws Exception { // 获取要执行办法名，是否有必要应用默认的execute也早在proxy的prepare中解决过了 String methodName = proxy.getMethod(); if (LOG.isDebugEnabled()) { LOG.debug("Executing action method = #0", methodName); } String timerKey = "invokeAction: " + proxy.getActionName(); try { UtilTimerStack.push(timerKey); Object methodResult; try { //应用onglUtil这个工具类执行action的办法，具体的就要理解onglutil做了啥了。。 methodResult = ognlUtil.callMethod(methodName + "()", getStack().getContext(), action); } catch (MethodFailedException e) { // if reason is missing method, try find version with "do" prefix if (e.getReason() instanceof NoSuchMethodException) { try { String altMethodName = "do" + methodName.substring(0, 1).toUpperCase() + methodName.substring(1) + "()"; methodResult = ognlUtil.callMethod(altMethodName, getStack().getContext(), action); } catch (MethodFailedException e1) { // if still method doesn't exist, try checking UnknownHandlers if (e1.getReason() instanceof NoSuchMethodException) { if (unknownHandlerManager.hasUnknownHandlers()) { try { methodResult = unknownHandlerManager.handleUnknownMethod(action, methodName); } catch (NoSuchMethodException e2) { // throw the original one throw e; } } else { // throw the original one throw e; } // throw the original exception as UnknownHandlers weren't able to handle invocation as well if (methodResult == null) { throw e; } } else { // exception isn't related to missing action method, throw it throw e1; } } } else { // exception isn't related to missing action method, throw it throw e; } } // 解决执行完办法后拿到的methodResult，而后返回解决后的后果 return saveResult(actionConfig, methodResult); } catch (NoSuchPropertyException e) { throw new IllegalArgumentException("The " + methodName + "() is not defined in action " + getAction().getClass() + ""); } catch (MethodFailedException e) { // We try to return the source exception. Throwable t = e.getCause(); 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); }}saveReult：
// 如果methodresult是Result类型就保留到explicitResult（explicitResult是actioninvocation中一个Rsult类型的全局变量）上，返回null，否则间接返回string的methodResultprotected String saveResult(ActionConfig actionConfig, Object methodResult) { if (methodResult instanceof Result) { this.explicitResult = (Result) methodResult; // Wire the result automatically container.inject(explicitResult); return null; } else { return (String) methodResult; }}再回到invoke中，执行完action之后有一段代码
// now execute the result, if we're supposed toif (proxy.getExecuteResult()) { executeResult();} // 具体的executeResult如下private void executeResult() throws Exception { // create a Result result = createResult(); String timerKey = "executeResult: " + getResultCode(); try { UtilTimerStack.push(timerKey); if (result != null) { // 执行Result的execute 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); }} //具体的createResult如下public Result createResult() throws Exception { LOG.trace("Creating result related to resultCode [#0]", resultCode); if (explicitResult != null) { 把之前在saveResult中保留到explicitResult中的值赋值到ret中，同时explicitResult清空 Result ret = explicitResult; explicitResult = null; // 如果explicitResult不为空，即之前取得的后果间接就是一个result类型，那么间接返回 // 否则之前取得后果是一个一般的字符串，须要找到字符串对应的Result return ret; } ActionConfig config = proxy.getConfig(); // 配置文件中配置的result节点信息 Map<String, ResultConfig> results = config.getResults(); ResultConfig resultConfig = null; try { // 尝试获取resultCode对应的resultconfig resultConfig = results.get(resultCode); } catch (NullPointerException e) { if (LOG.isDebugEnabled()) { LOG.debug("Got NPE trying to read result configuration for resultCode [#0]", resultCode); } } if (resultConfig == null) { // If no result is found for the given resultCode, try to get a wildcard '*' match. resultConfig = results.get("*"); } if (resultConfig != null) { try { // 依据resultconfig 结构一个Result返回 return objectFactory.buildResult(resultConfig, invocationContext.getContextMap()); } catch (Exception e) { if (LOG.isErrorEnabled()) { LOG.error("There was an exception while instantiating the result of type #0", e, resultConfig.getClassName()); } throw new XWorkException(e, resultConfig); } } else if (resultCode != null && !Action.NONE.equals(resultCode) && unknownHandlerManager.hasUnknownHandlers()) { return unknownHandlerManager.handleUnknownResult(invocationContext, proxy.getActionName(), proxy.getConfig(), resultCode); } return null;}那么，Result到底是什么？
// Result接口很简略，只提供一个execute办法public interface Result extends Serializable { /** * Represents a generic interface for all action execution results. * Whether that be displaying a webpage, generating an email, sending a JMS message, etc. * * @param invocation the invocation context. * @throws Exception can be thrown. */ public void execute(ActionInvocation invocation) throws Exception;}struts在配置action的时候，会相应的配置result节点，其中包含result的type，每一个type其实对应一个具体的Result实现类，下面的objectFactory.buildResult实则调的是resultFactory的buildResult。
默认的ResultFactory是StrutsResultFactory
public Result buildResult(ResultConfig resultConfig, Map<String, Object> extraContext) throws Exception { // config中有配置type，找到对应的具体result实现类 String resultClassName = resultConfig.getClassName(); Result result = null; if (resultClassName != null) { // 生成具体result实现类的实例 // 回到下面的result.execute，就可晓得这个时候获取了result实例，不同type的result的execute有不同的解决 result = (Result) objectFactory.buildBean(resultClassName, extraContext); Map<String, String> params = resultConfig.getParams(); if (params != null) { setParameters(extraContext, result, params); } } return result;}至此，大略晓得了struts的动静代理的应用，如何用动静代理模式解决action申请和拦截器，如何解决result。
todo：
1 下面只是大略流程，可找几点具体分析
2 context相干
3 struts的工厂类 ObjectFactory及具体的各种工厂类
4 msite当初应用的json result是如何解决的。