spring mvc 源码简要分析

关于web项目，运用比较多的是过滤器和拦截器

过滤器基于责任链设计模式

创建过滤器链

/ Create the filter chain for this requestApplicationFilterChain filterChain =        ApplicationFilterFactory.createFilterChain(request, wrapper, servlet);

//调用

private void internalDoFilter(ServletRequest request,                              ServletResponse response)    throws IOException, ServletException {

    // Call the next filter if there is one    if (pos < n) {        ApplicationFilterConfig filterConfig = filters[pos++];        try {            Filter filter = filterConfig.getFilter();

            if (request.isAsyncSupported() && "false".equalsIgnoreCase(                    filterConfig.getFilterDef().getAsyncSupported())) {                request.setAttribute(Globals.ASYNC_SUPPORTED_ATTR, Boolean.FALSE);            }            if( Globals.IS_SECURITY_ENABLED ) {                final ServletRequest req = request;                final ServletResponse res = response;                Principal principal =                    ((HttpServletRequest) req).getUserPrincipal();

                Object[] args = new Object[]{req, res, this};                SecurityUtil.doAsPrivilege ("doFilter", filter, classType, args, principal);            } else {                filter.doFilter(request, response, this);            }        } catch (IOException | ServletException | RuntimeException e) {            throw e;        } catch (Throwable e) {            e = ExceptionUtils.unwrapInvocationTargetException(e);            ExceptionUtils.handleThrowable(e);            throw new ServletException(sm.getString("filterChain.filter"), e);        }        return;    }

    // We fell off the end of the chain -- call the servlet instance    try {        if (ApplicationDispatcher.WRAP_SAME_OBJECT) {            lastServicedRequest.set(request);            lastServicedResponse.set(response);        }

        if (request.isAsyncSupported() && !servletSupportsAsync) {            request.setAttribute(Globals.ASYNC_SUPPORTED_ATTR,                    Boolean.FALSE);        }        // Use potentially wrapped request from this point        if ((request instanceof HttpServletRequest) &&                (response instanceof HttpServletResponse) &&                Globals.IS_SECURITY_ENABLED ) {            final ServletRequest req = request;            final ServletResponse res = response;            Principal principal =                ((HttpServletRequest) req).getUserPrincipal();            Object[] args = new Object[]{req, res};            SecurityUtil.doAsPrivilege("service",                                       servlet,                                       classTypeUsedInService,                                       args,                                       principal);        } else {            servlet.service(request, response);        }    } catch (IOException | ServletException | RuntimeException e) {        throw e;    } catch (Throwable e) {        e = ExceptionUtils.unwrapInvocationTargetException(e);        ExceptionUtils.handleThrowable(e);        throw new ServletException(sm.getString("filterChain.servlet"), e);    } finally {        if (ApplicationDispatcher.WRAP_SAME_OBJECT) {            lastServicedRequest.set(null);            lastServicedResponse.set(null);        }    }

拦截器基于动态代理 
// 执行拦截器的prehandle
if (!mappedHandler.applyPreHandle(processedRequest, response)) {
return;
}

// Actually invoke the handler.
mv = ha.handle(processedRequest, response, mappedHandler.getHandler());

// 执行拦截器的PostHandle
mappedHandler.applyPostHandle(processedRequest, response, mv);

// 执行拦截器的AfterCompletion
if (mappedHandler != null) {
mappedHandler.triggerAfterCompletion(request, response, null);
}

原文地址：https://www.cnblogs.com/wchxj/p/11784111.html