解决问题：
在service层，使用RequestContextHolder获取controller层请求（HttpServletRequest）响应信息（HttpServletResponse）
RequestContextHolder使用：
RequestContextHolder含义持有上下文的Request容器
HttpServletRequest request= ((ServletRequestAttributes) (RequestContextHolder.getRequestAttributes())).getRequest();
HttpServletResponse response= ((ServletRequestAttributes) (RequestContextHolder.getRequestAttributes())).getResponse();
疑问：
request和response怎么和当前请求挂钩?查看RequestContextHolder类，ThreadLocal保存当前线程Request
private static final ThreadLocal<RequestAttributes> requestAttributesHolder =new NamedThreadLocal<>("Request attributes");private static final ThreadLocal<RequestAttributes> inheritableRequestAttributesHolder =new NamedInheritableThreadLocal<>("Request context");
所有对象是一个servlet，servlet的实现是DispatcherServlet，DispatcherServlet父类也就是它的爸爸FrameworkServlet
查看FrameworkServlet
运行servlet，一般是运行service方法，在FrameworkServlet查看service方法，可以看到service方法会执行processRequest请求
@Override
protected void service(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {HttpMethod httpMethod = HttpMethod.resolve(request.getMethod());if (httpMethod == HttpMethod.PATCH || httpMethod == null) {processRequest(request, response);}else {super.service(request, response);}
}
而对象赋值，就是processRequest请求，
protected final void processRequest(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {long startTime = System.currentTimeMillis();Throwable failureCause = null;LocaleContext previousLocaleContext = LocaleContextHolder.getLocaleContext();LocaleContext localeContext = buildLocaleContext(request);RequestAttributes previousAttributes = RequestContextHolder.getRequestAttributes();ServletRequestAttributes requestAttributes = buildRequestAttributes(request, response, previousAttributes);WebAsyncManager asyncManager = WebAsyncUtils.getAsyncManager(request);asyncManager.registerCallableInterceptor(FrameworkServlet.class.getName(), new RequestBindingInterceptor());initContextHolders(request, localeContext, requestAttributes);try {doService(request, response);}catch (ServletException | IOException ex) {failureCause = ex;throw ex;}catch (Throwable ex) {failureCause = ex;throw new NestedServletException("Request processing failed", ex);}finally {resetContextHolders(request, previousLocaleContext, previousAttributes);if (requestAttributes != null) {requestAttributes.requestCompleted();}logResult(request, response, failureCause, asyncManager);publishRequestHandledEvent(request, response, startTime, failureCause);}
}
initContextHolders方法初始化
private void initContextHolders(HttpServletRequest request,@Nullable LocaleContext localeContext, @Nullable RequestAttributes requestAttributes) {if (localeContext != null) {LocaleContextHolder.setLocaleContext(localeContext, this.threadContextInheritable);}if (requestAttributes != null) {RequestContextHolder.setRequestAttributes(requestAttributes, this.threadContextInheritable);}
}
可以看出ThreadLocal 的Request 请求在setLocaleContext进行赋值