How to find the content-length of Page <Entity> to be passed as the http header?

Question

I am using spring boot along with Netflix Eureka. I need to find the total length of Page to set the content-length in the HTTP response header. My controller is like this ...

Page<exampleEntity> examplePage = null;
examplePage=exampleService.getFuntion(request, params);
HttpHeaders headers = new HttpHeaders();
headers.setContentLength(???);
return new ResponseEntity<>(Page, HttpHeaders ,HttpStatus.OK);

...

could anyone please help?

Answer 1

ByteArrayOutputStream bos = new ByteArrayOutputStream();
ObjectOutputStream out = null;
try {
  out = new ObjectOutputStream(bos);   
  out.writeObject(yourObject);
  out.flush();
  byte[] yourBytes = bos.toByteArray();
  
} finally {
  try {
    bos.close();
  } catch (IOException ex) {
    // ignore close exception
  }
}

Then yourBytes.length is what you need