标签：this async 技术 protected pos control style 主题 mode
运行helloWorld示例进入调试界面。
DispatcherServlet：前端控制器
DispatcherServlet.doDispatch(HttpServletRequest, HttpServletResponse) line: 945 DispatcherServlet.doService(HttpServletRequest, HttpServletResponse) line: 876 DispatcherServlet(FrameworkServlet).processRequest(HttpServletRequest, HttpServletResponse) line: 931 DispatcherServlet(FrameworkServlet).doGet(HttpServletRequest, HttpServletResponse) line: 822 DispatcherServlet(HttpServlet).service(HttpServletRequest, HttpServletResponse) line: 624 DispatcherServlet(FrameworkServlet).service(HttpServletRequest, HttpServletResponse) line: 807 DispatcherServlet(HttpServlet).service(ServletRequest, ServletResponse) line: 731
由上进入源码查看
DispatcherServlet(FrameworkServlet).service(HttpServletRequest, HttpServletResponse) line: 807
的
public abstract class FrameworkServlet extends HttpServletBean implements ApplicationContextAware {
...
service();
}
HttpServletBean 的实现
public abstract class HttpServletBean extends HttpServlet implements EnvironmentCapable, EnvironmentAware {}
接下来重点关注doDispatch()
protected void doDispatch(HttpServletRequest request, HttpServletResponse response) throws Exception { HttpServletRequest processedRequest = request; HandlerExecutionChain mappedHandler = null; boolean multipartRequestParsed = false; WebAsyncManager asyncManager = WebAsyncUtils.getAsyncManager(request); try { ModelAndView mv = null; Exception dispatchException = null; try { processedRequest = checkMultipart(request); multipartRequestParsed = processedRequest != request; // Determine handler for the current request. //1、根据当前请求地址找到哪个处理器来处理请求 mappedHandler = getHandler(processedRequest); if (mappedHandler == null || mappedHandler.getHandler() == null) { //2、如果找不到报错 noHandlerFound(processedRequest, response); return; } // Determine handler adapter for the current request. //2\为当前请求确定适配器 HandlerAdapter ha = getHandlerAdapter(mappedHandler.getHandler()); // Process last-modified header, if supported by the handler. String method = request.getMethod(); boolean isGet = "GET".equals(method); if (isGet || "HEAD".equals(method)) { long lastModified = ha.getLastModified(request, mappedHandler.getHandler()); if (logger.isDebugEnabled()) { String requestUri = urlPathHelper.getRequestUri(request); logger.debug("Last-Modified value for [" + requestUri + "] is: " + lastModified); } if (new ServletWebRequest(request, response).checkNotModified(lastModified) && isGet) { return; } } if (!mappedHandler.applyPreHandle(processedRequest, response)) { return; } try { // Actually invoke the handler. //真正执行方法 mv = ha.handle(processedRequest, response, mappedHandler.getHandler()); } finally { if (asyncManager.isConcurrentHandlingStarted()) { return; } } applyDefaultViewName(request, mv); mappedHandler.applyPostHandle(processedRequest, response, mv); } catch (Exception ex) { dispatchException = ex; } //处理响应结果 processDispatchResult(processedRequest, response, mappedHandler, mv, dispatchException); } catch (Exception ex) { triggerAfterCompletion(processedRequest, response, mappedHandler, ex); } catch (Error err) { triggerAfterCompletionWithError(processedRequest, response, mappedHandler, err); } finally { if (asyncManager.isConcurrentHandlingStarted()) { // Instead of postHandle and afterCompletion mappedHandler.applyAfterConcurrentHandlingStarted(processedRequest, response); return; } // Clean up any resources used by a multipart request. if (multipartRequestParsed) { cleanupMultipart(processedRequest); } } }
1、根据当前请求地址找到哪个处理器来处理请求
mappedHandler = getHandler(processedRequest);
protected HandlerExecutionChain getHandler(HttpServletRequest request) throws Exception {
for (HandlerMapping hm : this.handlerMappings) {
if (logger.isTraceEnabled()) {
logger.trace(
"Testing handler map [" + hm + "] in DispatcherServlet with name ‘" + getServletName() + "‘");
}
HandlerExecutionChain handler = hm.getHandler(request);
if (handler != null) {
return handler;
}
}
return null;
}
2、为当前请求确定适配器
HandlerAdapter ha = getHandlerAdapter(mappedHandler.getHandler());
protected HandlerAdapter getHandlerAdapter(Object handler) throws ServletException {
for (HandlerAdapter ha : this.handlerAdapters) {
if (logger.isTraceEnabled()) {
logger.trace("Testing handler adapter [" + ha + "]");
}
if (ha.supports(handler)) {
return ha;
}
}
throw new ServletException("No adapter for handler [" + handler +
"]: The DispatcherServlet configuration needs to include a HandlerAdapter that supports this handler");
}
/** MultipartResolver used by this servlet 文件上传解析器*/ private MultipartResolver multipartResolver; /** LocaleResolver used by this servlet 国际化解析器*/ private LocaleResolver localeResolver; /** ThemeResolver used by this servlet 主题解析器*/ private ThemeResolver themeResolver; /** List of HandlerMappings used by this servlet 保存了请求与类的映射关系（哪个请求用哪个类来处理）*/ private List<HandlerMapping> handlerMappings; /** List of HandlerAdapters used by this servlet适配器；用来执行控制器（处理器）目标方法的*/ private List<HandlerAdapter> handlerAdapters; /** List of HandlerExceptionResolvers used by this servlet 异常解析器*/ private List<HandlerExceptionResolver> handlerExceptionResolvers; /** RequestToViewNameTranslator used by this servlet 转化器*/ private RequestToViewNameTranslator viewNameTranslator; /** FlashMapManager used by this servletFlashMap 管理器 */ private FlashMapManager flashMapManager; /** List of ViewResolvers used by this servlet视图解析器 */ private List<ViewResolver> viewResolvers;
标签：this async 技术 protected pos control style 主题 mode
原文地址：http://www.cnblogs.com/limingxian537423/p/7279021.html
