How to implement a global exception handler used by all the controllers ?

Create a Controller advice, which will be called on each controller.

• Implement ResponseBodyAdvice
  (methods : beforeBodyWrite, supports)
  OR / AND 
• Implement RequestBodyAdvice
  (methods : beforeBodyRead, afterBodyRead, handleEmptyBody, supports)

supports method can be used to check proper content type and return boolean.

For a global exception handler, create a Controller advice and check request or manipulate the response.