Custom HTTP reason phrase using ExceptionMapper

Question

I have defined the following Exception Mapper to handle the custom HttpCustomException

package com.myapp.apis;

import com.myapp.apis.model.HttpCustomException;
import com.myapp.apis.model.HttpCustomExceptionStatusType;
import com.myapp.apis.model.HttpCustomNotAuthorizedException;

import javax.ws.rs.core.Response;
import javax.ws.rs.ext.ExceptionMapper;
import javax.ws.rs.ext.Provider;

@Provider
public class HttpCustomExceptionMapper implements ExceptionMapper <HttpCustomException> {

  @Override
  public Response toResponse (HttpCustomException e) {
    Response response = Response.status (new HttpCustomExceptionStatusType (Response.Status.UNAUTHORIZED, e.getMessage ())).build ();
    if (e instanceof HttpCustomNotAuthorizedException) {
      response = Response.status (new HttpCustomExceptionStatusType (Response.Status.INTERNAL_SERVER_ERROR, e.getMessage ())).build ();
    }

    System.out.println ("HttpCustomExceptionMapper: " + response.getStatus () + ", " + response.getStatusInfo ().getReasonPhrase ());
    return response;
  }
}

When a HttpCustomNotAuthorizedException is thrown in the code, I can see the log message defined in the end of the toResponse method, in catalina.out. So, the HttpCustomExceptionMapper class is being invoked during the request processing. But, in the final response, I see in the client, I only see the standard Not Authorized message and not the custom message I set in the Response.

Why does this happen?

Answer 1

You should note that the current version of HTTP protocol (HTTP/2) does not support a reason phrase at all. It has been removed from the protocol.

Thus support for sending a reason phrase has been removed from Tomcat 9.0 onwards. In Tomcat 7.0, 8.5 support for sending a custom reason phrase is off by default (can be enabled with a system property, org.apache.coyote.USE_CUSTOM_STATUS_MSG_IN_HEADER). In 8.5 you also should set sendReasonPhrase="true" on a Connector.