Get the content size returned in the request

Question

Hello, I’m using an Interceptor that will intercept before and after the request. The goal of this is to get the size of the content sent and returned, however, I do not know a way to get the answer, it seems that the sponse has no method to catch it

    @Component
public class DataUsageInterceptor extends HandlerInterceptorAdapter {

    @Override
    public boolean preHandle(
            HttpServletRequest request,
            HttpServletResponse response,
            Object handler
    ) throws Exception {
        System.out.println("Tamanho da requisicao: " + request.getContentLength());
        return super.preHandle(request, response, handler);
    }

    @Override
    public void afterCompletion(
            HttpServletRequest request,
            HttpServletResponse response,
            Object handler, Exception ex
    ) throws Exception {

        System.out.println("Tamanho da resposta: ??");

        super.afterCompletion(request, response, handler, ex);
    }
}

Answer 1

You can read the content-length Response Header to get this information:

response.getHeader("content-length");

This information corresponds to the size of the compressed Response (if applicable) by means of Gzip ¹. Then a 25 KB size Response can have, uncompressed, more than 120 KB.

^{¹: You can check if you have gzip enabled by reading the reponse header content-encoding.}