How to add Content-Length to JAXRS

Question

In my response, I would like to add the size of the JSON to header, Here is what I tried and did not work (the response was empty):

return Response.ok(OBJECT_MAPPER.writeValueAsString(myObject), MediaType.APPLICATION_JSON).header(HttpHeaders.CONTENT_LENGTH), 20).build();

As you can see, I am hard coding the length, but it would be great if I could use the API to do it.

Solution Well, byte size can be returned as below, depending on encoding. Below code would do it without implementing MessageBodyWriter interface:

String str = OBJECT_MAPPER.writeValueAsString(myObject);
return Response.ok(str , MediaType.APPLICATION_JSON).header(HttpHeaders.CONTENT_LENGTH), str.getBytes("UTF-8").length)).build();

Answer 1

implementing MessageBodyWriter interface:

String str = OBJECT_MAPPER.writeValueAsString(myObject);
return Response.ok(str , MediaType.APPLICATION_JSON).header(HttpHeaders.CONTENT_LENGTH), str.getBytes("UTF-8").length)).build();