①从web.xml文件中可以看出jfinal框架本质上是一个Filter
<!DOCTYPE web-app PUBLIC "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN" "http://java.sun.com/dtd/web-app_2_3.dtd" > <web-app> <display-name>jfinal</display-name> <filter> <filter-name>jfinal</filter-name> <filter-class>com.jfinal.core.JFinalFilter</filter-class> <init-param> <param-name>configClass</param-name> <param-value>com.demo.config.DemoConfig</param-value> </init-param> </filter> <filter-mapping> <filter-name>jfinal</filter-name> <url-pattern>/*</url-pattern> </filter-mapping> <welcome-file-list> <welcome-file>index.html</welcome-file> </welcome-file-list> </web-app>
②JFinalFilter重写了doFilter方法,所有的处理都在该方法中完成
public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain) throws IOException, ServletException { HttpServletRequest request = (HttpServletRequest)req; HttpServletResponse response = (HttpServletResponse)res; request.setCharacterEncoding(encoding); String target = request.getRequestURI(); if (contextPathLength != 0) target = target.substring(contextPathLength); boolean[] isHandled = {false}; try { handler.handle(target, request, response, isHandled); } catch (Exception e) { if (log.isErrorEnabled()) { String qs = request.getQueryString(); log.error(qs == null ? target : target + "?" + qs, e); } } if (isHandled[0] == false) chain.doFilter(request, response); }
Handler的实现类
③Hander接口有多个实现类,我们分析ActionHandler的handler()方法
/** * handle * 1: Action action = actionMapping.getAction(target) * 2: new ActionInvocation(...).invoke() * 3: render(...) */ public final void handle(String target, HttpServletRequest request, HttpServletResponse response, boolean[] isHandled) { if (target.indexOf(".") != -1) { return ; } isHandled[0] = true; String[] urlPara = {null}; Action action = actionMapping.getAction(target, urlPara); //根据ActionMapping中的映射获取处理当前请求的Action if (action == null) { if (log.isWarnEnabled()) { String qs = request.getQueryString(); log.warn("404 Action Not Found: " + (qs == null ? target : target + "?" + qs)); } renderFactory.getErrorRender(404).setContext(request, response).render(); return ; } try { Controller controller = action.getControllerClass().newInstance(); //实例化Controller处理类 controller.init(request, response, urlPara[0]); //初始化Controller if (devMode) { boolean isMultipartRequest = ActionReporter.reportCommonRequest(controller, action); new ActionInvocation(action, controller).invoke(); if (isMultipartRequest) ActionReporter.reportMultipartRequest(controller, action); } else { new ActionInvocation(action, controller).invoke(); //调用Controller中相应的处理方法(详见) } Render render = controller.getRender(); //根据Controller中的设置获取数据和视图的对应类Render if (render instanceof ActionRender) { //如果render是一个ActionRender,则再交给对应的Handler处理 String actionUrl = ((ActionRender)render).getActionUrl(); if (target.equals(actionUrl)) throw new RuntimeException("The forward action url is the same as before."); else handle(actionUrl, request, response, isHandled); return ; } if (render == null) //如果render,则使用默认Render render = renderFactory.getDefaultRender(action.getViewPath() + action.getMethodName()); render.setContext(request, response, action.getViewPath()).render(); //调用Render实现类的render()方法进行渲染 } catch (RenderException e) { if (log.isErrorEnabled()) { String qs = request.getQueryString(); log.error(qs == null ? target : target + "?" + qs, e); } } catch (ActionException e) {
Render的实现类
④在ActionInvocation的invoke()方法中,请求先经过一系列拦截器
/** * Invoke the action. */ public void invoke() { if (index < inters.length) inters[index++].intercept(this); else if (index++ == inters.length) // index++ ensure invoke action only one time // try {action.getMethod().invoke(controller, NULL_ARGS);} catch (Exception e) {throw new RuntimeException(e);} try { action.getMethod().invoke(controller, NULL_ARGS); } catch (InvocationTargetException e) { Throwable cause = e.getTargetException(); if (cause instanceof RuntimeException) throw (RuntimeException)cause; throw new RuntimeException(e); } catch (RuntimeException e) { throw e; } catch (Exception e) { throw new RuntimeException(e); } }