在springmvc中使用requestContextListener获取全部的request对象

RequestContextListener实现了 ServletRequestListener ,在其覆盖的requestInitialized(ServletRequestEvent requestEvent)方法中,将request最终设置到了RequestContextHolder中.

public class RequestContextListener implements ServletRequestListener {

    private static final String REQUEST_ATTRIBUTES_ATTRIBUTE =
            RequestContextListener.class.getName() + ".REQUEST_ATTRIBUTES";

    @Override
    public void requestInitialized(ServletRequestEvent requestEvent) {
        if (!(requestEvent.getServletRequest() instanceof HttpServletRequest)) {
            throw new IllegalArgumentException(
                    "Request is not an HttpServletRequest: " + requestEvent.getServletRequest());
        }
        HttpServletRequest request = (HttpServletRequest) requestEvent.getServletRequest();//从事件对象中获取request对象
        ServletRequestAttributes attributes = new ServletRequestAttributes(request);//将request设置到servletRequestAttributes中
        request.setAttribute(REQUEST_ATTRIBUTES_ATTRIBUTE, attributes);//反过来将servletRequestAttributes设置到request中
        LocaleContextHolder.setLocale(request.getLocale());
        RequestContextHolder.setRequestAttributes(attributes);//再将servletRequestAttributes设置到requestContextHolder中
    }

代码中获取该request的步骤:

HttpServletRequest request = ((ServletRequestAttributes) (RequestContextHolder.getRequestAttributes()))
                .getRequest();// 返回了RequestAttributes接口,将其强转为ServletRequestAttributes实现类

使用上述方法前,需要先配置RequestContextListener监听器:

<listener>
        <listener-class>org.springframework.web.context.request.RequestContextListener</listener-class>
    </listener>