如果是@ResponseBody handler返回的response，在interceptor中无法再对response进行操作。
其response.isCommitted() == true
因为@ResponseBody是由HttpMessageConverter处理请求，写出到response，并设置为committed。

Specifically, the @ResponseBody is written and committed by ServletHandlerMethodInvoker before HandlerInterceptor.postHandle is called. I would have expected the order to be similar to if I had omitted the @ResponseBody and used a MarshallingView instead, i.e.

• HandlerInterceptor.preHandle
• (handler is invoked)
• HandlerInterceptor.postHandle
• (response is written)
• HandlerInterceptor.afterCompletion

With @ResponseBody, the 3rd and 4th steps are reversed.

• Make HandlerInterceptor play nice with @ResponseBody [SPR-7897] · Issue #12553 · spring-projects/spring-framework

原理探究

执行顺序：

1. 先执行Controller
2. 再执行returnValueHandler
   1. 执行ResponseBodyAdvice
   2. 执行HttpMessageConverter【此处HttpMessageConverter将response设置为了isCommitted】
3. 执行HandlerIntercepter.postHandle()