public void handle()

in server/src/main/java/org/apache/calcite/avatica/server/AvaticaJsonHandler.java [88:156]
61 lines of code
11 McCabe index (conditional complexity)

  public void handle(String target, Request baseRequest,
      HttpServletRequest request, HttpServletResponse response)
      throws IOException, ServletException {
    try (Context ctx = requestTimer.start()) {
      if (!isUserPermitted(serverConfig, baseRequest, request, response)) {
        LOG.debug("HTTP request from {} is unauthenticated and authentication is required",
            request.getRemoteAddr());
        return;
      }

      response.setContentType("application/json;charset=utf-8");
      response.setStatus(HttpServletResponse.SC_OK);
      if (request.getMethod().equals("POST")) {
        // First look for a request in the header, then look in the body.
        // The latter allows very large requests without hitting HTTP 413.
        String rawRequest = request.getHeader("request");
        if (rawRequest == null) {
          // Avoid a new buffer creation for every HTTP request
          final UnsynchronizedBuffer buffer = threadLocalBuffer.get();
          try (ServletInputStream inputStream = request.getInputStream()) {
            byte[] bytes = AvaticaUtils.readFullyToBytes(inputStream, buffer);
            String encoding = request.getCharacterEncoding();
            if (encoding == null) {
              encoding = "UTF-8";
            }
            rawRequest = AvaticaUtils.newString(bytes, encoding);
          } finally {
            // Reset the offset into the buffer after we're done
            buffer.reset();
          }
        }
        final String jsonRequest = rawRequest;
        LOG.trace("request: {}", jsonRequest);

        HandlerResponse<String> jsonResponse;
        try {
          if (null != serverConfig && serverConfig.supportsImpersonation()) {
            String remoteUser = serverConfig.getRemoteUserExtractor().extract(request);
            jsonResponse = serverConfig.doAsRemoteUser(remoteUser,
                request.getRemoteAddr(), new Callable<HandlerResponse<String>>() {
                  @Override public HandlerResponse<String> call() {
                    return jsonHandler.apply(jsonRequest);
                  }
                });
          } else {
            jsonResponse = jsonHandler.apply(jsonRequest);
          }
        } catch (RemoteUserExtractionException e) {
          LOG.debug("Failed to extract remote user from request", e);
          jsonResponse = jsonHandler.unauthenticatedErrorResponse(e);
        } catch (RemoteUserDisallowedException e) {
          LOG.debug("Remote user is not authorized", e);
          jsonResponse = jsonHandler.unauthorizedErrorResponse(e);
        } catch (BadRequestException e) {
          LOG.debug("Bad request exception", e);
          jsonResponse = jsonHandler.badRequestErrorResponse(e);
        } catch (Exception e) {
          LOG.debug("Error invoking request from {}", baseRequest.getRemoteAddr(), e);
          jsonResponse = jsonHandler.convertToErrorResponse(e);
        }

        LOG.trace("response: {}", jsonResponse);
        baseRequest.setHandled(true);
        // Set the status code and write out the response.
        response.setStatus(jsonResponse.getStatusCode());
        response.getWriter().println(jsonResponse.getResponse());
      }
    }
  }