public String invoke() throws Exception {

String profileKey = "invoke: "

try {

UtilTimerStack.push(profileKey);

if (executed) {

throw new IllegalStateException("Action has already executed");

}

//遞歸運行interceptor

if (interceptors.hasNext())

{ //interceptors是InterceptorMapping實際上是像一個像

//通過調用Invocation.invoke()實現遞歸牡循環

final InterceptorMapping interceptor = interceptors.next();

String interceptorMsg = "interceptor: " + interceptor.getName();

UtilTimerStack.push(interceptorMsg);

try {

//在每一個Interceptor的方法中都會return invocation.invoke()

resultCode = interceptor.getInterceptor().intercept(DefaultActionInvocation.this);

}

finally {

UtilTimerStack.pop(interceptorMsg);

}

} else {

//當全部interceptor都運行完,最後運行Action,invokeActionOnly會調用//invokeAction()方法

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

//在Result返回之前調用preResultListeners

//通過executed控制,僅僅運行一次

if (!executed) {

if (preResultListeners != null) {

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

//運行result。

if (proxy.getExecuteResult()) {

executeResult();

}

executed = true;

}

return resultCode;

}

finally {

UtilTimerStack.pop(profileKey);

}

}