转: 俯瞰Struts2整体流程（6）上

3.1??Struts 2工作流程

public?class?FilterDispatcher?implements?StrutsStatics,?Filter?{

????/**

?????*?定义一个Log实例

?????*/

private?static?final?Log?LOG?=?LogFactory.getLog(FilterDispatcher.class);

…?...

????/**

?????*?存放属性文件中的.STRUTS_I18N_ENCODING值

?????*/

????private?static?String?encoding;

????/**

?????*?定义ActionMapper实例

?????*/

????private?static?ActionMapper?actionMapper;

????/**

?????*?定义FilterConfig实例

?????*/

????private?FilterConfig?filterConfig;

????protected?Dispatcher?dispatcher;

????/**

?????*?创建一个默认的dispatcher，初始化filter

?????*?设置默认的packages?????*

?????*/

????public?void?init(FilterConfig?filterConfig)?throws?ServletException?{

?????this.filterConfig?=?filterConfig;

???????dispatcher?=?createDispatcher(filterConfig);

????????dispatcher.init();

????????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);

????}

????//销毁filter方法

???public?void?destroy()?{

????????if?(dispatcher?==?null)?{

????????????LOG.warn("something?is?seriously?wrong,?Dispatcher?is?not?initialized?(null)?");

????????}?else?{

????????????dispatcher.cleanup();

????????}

????}

????/**

?????*?处理一个Action或者资源请求

?????*?<p/>

?????*?filter尝试将请求同action?mapping相匹配

?????*?如果找到，将执行dispatcher的serviceAction方法

?????*?如果Action处理失败,?doFilter将建立一个异常

?????*?<p/>

?????*?如果请求静态资源

?????*?资源将被直接复制给?response

?????*?<p/>

?????*?如果找不到匹配Action?或者静态资源，则直接跳出

?????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?{

????????????UtilTimerStack.push(timerKey);

????????????request?=?prepareDispatcherAndWrapRequest(request,?response);

????????????ActionMapping?mapping;

????????????try?{

????????????????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;

????????????}

????????????if?(mapping?==?null)?{

????????????????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?{

????????????????????//为一个普通的request,?则通过

????????????????????chain.doFilter(request,?response);

????????????????}

????????????????return;

????????????}

/**

*这个方法询问ActionMapper是否需要调用某个Action来处理这个（request）请求，

*如果ActionMapper决定需要调用某个Action，

*FilterDispatcher则把请求的处理交给ActionProxy

????????????dispatcher.serviceAction(request,?response,?servletContext,?mapping);

????????}?finally?{

????????????try?{

????????????????ActionContextCleanUp.cleanUp(req);

????????????}?finally?{

????????????????UtilTimerStack.pop(timerKey);

????????????}

????????}

}

…?…

}

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