http://hi.baidu.com/liangzhongbo/item/07be3a560c16bc13da163536
org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter
初始化:
public void init(FilterConfig filterConfig)
throws
ServletException
{
InitOperations init = new
InitOperations();
FilterHostConfig config = new
FilterHostConfig(filterConfig);
init.initLogging(config);
Dispatcher dispatcher = init.initDispatcher(config);
init.initStaticContentLoader(config, dispatcher);
prepare = new
PrepareOperations(filterConfig.getServletContext(), dispatcher);
execute = new ExecuteOperations(filterConfig.getServletContext(),
dispatcher);
excludedPatterns =
init.buildExcludedPatternsList(dispatcher);
postInit(dispatcher,
filterConfig);
init.cleanup();
break
MISSING_BLOCK_LABEL_108;
Exception exception;
exception;
init.cleanup();
throw exception;
}
执行任务
public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain)
throws IOException, ServletException
{
HttpServletRequest request;
HttpServletResponse response;
request = (HttpServletRequest)req;
response =
(HttpServletResponse)res;
prepare.setEncodingAndLocale(request,
response);
/*为当前线程创建ActionContext,ActionContext是ThreadLocal的，ActionContent其实就是一个线程安全的HashMap,它内部使用一个HashMap
来储存相关信息，这个map的构造是使用dispatcher.createContextMap(request, response, null, servletContext)来形成的，这个
map包括的信息有session,request,response，ServletContext，RequestMap，SessionMap等各种信息，可以通
个这个ActionContent取得各种信息，例如ActionContext.getContext().getSession()来获得当前的Session,
如果要获得request或者response必须用ServletActionContext它是ActionContent的子类，提供更多的方法，如
果是forward那也会新建一个新的ActionContent,这个新的ActionContent直接使用旧的ActionContent的数据来
构造*/
prepare.createActionContext(request, response);
prepare.assignDispatcherToThread();
if(excludedPatterns != null
&& prepare.isUrlExcluded(request, excludedPatterns))
{
chain.doFilter(request, response);
} else
{
request = prepare.wrapRequest(request);
org.apache.struts2.dispatcher.mapper.ActionMapping mapping =
prepare.findActionMapping(request, response, true);
if(mapping ==
null)
{
boolean handled =
execute.executeStaticResourceRequest(request, response);
if(!handled)
chain.doFilter(request, response);
} else
{
execute.executeAction(request,
response, mapping);
}
}
prepare.cleanupRequest(request);
break MISSING_BLOCK_LABEL_178;
Exception exception;
exception;
prepare.cleanupRequest(request);
throw exception;
}
struts2-流程详解-StrutsPrepareAndExecuteFilter
原文：http://www.cnblogs.com/wangjianbg/p/3555857.html