https://developer.mozilla.org/en-US/docs/Web/HTTP/Content_negotiation
accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,image/apng,*/*;q=0.8,application/signed-exchange;v=b3
content-type: text/html; charset=utf-8
content-type: application/xml; charset=utf-8
@Controller
HandlerMethod 方法返回的内容视图的地址
@RestController
= @Controller
+ @ResponseBody
HandlerMethod 方法返回的 Body 内容
ResponseEntity
= Body + Header
HandlerMethod = public 方法标注 @RequestMapping
Spring Web MVC 允许多套视图处理器(ViewResolver)并存
text/html -> Velocity
text/*
/
text/json -> themleaf
text/xml -> JSP
xxx.html -> Velocity
xxx.json -> themleaf
xxx.xml -> JSP
URL : http://acme.com/abc.json?format=application/xml
Accept : text/html