struts2源码分析 serviceAction

据说struts2是根据webwork修改过来的。下了struts2的代码看了看，果然跟webwork如出一辙。不过struts2貌似更简洁一些。

webwork的精华在于和http解耦，基于接口编程，以及利用IOC的解耦设计。拦截器是它非常漂亮的思想，当然实现也非常的漂亮。

下面是代码

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
//压栈
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();

String id = request.getParameter(XWorkContinuationConfig.CONTINUE_PARAM);
if (id != null) {
// remove the continue key from the params - we don't want to bother setting
// on the value stack since we know it won't work. Besides, this breaks devMode!
Map params = (Map) extraContext.get(ActionContext.PARAMETERS);
params.remove(XWorkContinuationConfig.CONTINUE_PARAM);

// and now put the key in the context to be picked up later by XWork
extraContext.put(XWorkContinuationConfig.CONTINUE_KEY, id);
}
//代理，实现了接口到实现的转换。
ActionProxy proxy = ActionProxyFactory.getFactory().createActionProxy(
configurationManager.getConfiguration(), 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();
//执行action
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) {
LOG.error("Could not execute action", e);
sendError(request, response, context, HttpServletResponse.SC_INTERNAL_SERVER_ERROR, e);
} finally {
UtilTimerStack.pop(timerKey);
}
}