springMVC 中几种获取request和response的方式

1.最简单方式：参数

例如：

@RequestMapping("/test")
@ResponseBody
public void saveTest(HttpServletRequest req, HttpServletResponse resp){
　　
}

2.加入监听器，然后在代码里面获取

HttpServletRequest req = ((ServletRequestAttributes)RequestContextHolder.getRequestAttributes()).getRequest();
HttpServletResponse resp = ((ServletWebRequest)RequestContextHolder.getRequestAttributes()).getResponse();

使用上述方法前,需要先在web.xml配置RequestContextListener监听器:

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

原理

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
}