java - How to handle Spring Boot's redirection to /error?

Question

I've encountered the same issue as in this question, using Spring Boot 1.3.0 and not having my controllers annotated with @RestController, just @Path and @Service. As the OP in that question says,

this is, to me, anything but sensible

I also can't understand why would they have it redirect to /error. And it is very likely that I'm missing something, because I can only give back 404s or 200s to the client.

My problem is that his solution doesn't seem to work with 1.3.0, so I have the following request flow: let's say my code throws a NullPointerException. It'll be handled by one of my ExceptionMappers

@Provider
public class GeneralExceptionMapper implements ExceptionMapper<Throwable> {

    private static final Logger LOGGER = LoggerFactory.getLogger(GeneralExceptionMapper.class);

    @Override
    public Response toResponse(Throwable exception) {
        LOGGER.error(exception.getLocalizedMessage());
        return Response.status(Response.Status.INTERNAL_SERVER_ERROR).build();
    }
}

And my code returns a 500, but instead of sending it back to the client, it tries to redirect it to /error. If I don't have another resource for that, it'll send back a 404.

2015-12-16 18:33:21.268  INFO 9708 --- [nio-8080-exec-1] o.glassfish.jersey.filter.LoggingFilter  : 1 * Server has received a request on thread http-nio-8080-exec-1
1 > GET http://localhost:8080/nullpointerexception
1 > accept: */*
1 > host: localhost:8080
1 > user-agent: curl/7.45.0

2015-12-16 18:33:29.492  INFO 9708 --- [nio-8080-exec-1] o.glassfish.jersey.filter.LoggingFilter  : 1 * Server responded with a response on thread http-nio-8080-exec-1
1 < 500

2015-12-16 18:33:29.540  INFO 9708 --- [nio-8080-exec-1] o.glassfish.jersey.filter.LoggingFilter  : 2 * Server has received a request on thread http-nio-8080-exec-1
2 > GET http://localhost:8080/error
2 > accept: */*
2 > host: localhost:8080
2 > user-agent: curl/7.45.0

2015-12-16 18:33:37.249  INFO 9708 --- [nio-8080-exec-1] o.glassfish.jersey.filter.LoggingFilter  : 2 * Server responded with a response on thread http-nio-8080-exec-1
2 < 404

And client's side (curl):

$ curl -v http://localhost:8080/nullpointerexception
* STATE: INIT => CONNECT handle 0x6000572d0; line 1090 (connection #-5000)
* Added connection 0. The cache now contains 1 members
*   Trying ::1...
* STATE: CONNECT => WAITCONNECT handle 0x6000572d0; line 1143 (connection #0)
* Connected to localhost (::1) port 8080 (#0)
* STATE: WAITCONNECT => SENDPROTOCONNECT handle 0x6000572d0; line 1240 (connection #0)
* STATE: SENDPROTOCONNECT => DO handle 0x6000572d0; line 1258 (connection #0)
> GET /nullpointerexception HTTP/1.1
> Host: localhost:8080
> User-Agent: curl/7.45.0
> Accept: */*
>
* STATE: DO => DO_DONE handle 0x6000572d0; line 1337 (connection #0)
* STATE: DO_DONE => WAITPERFORM handle 0x6000572d0; line 1464 (connection #0)
* STATE: WAITPERFORM => PERFORM handle 0x6000572d0; line 1474 (connection #0)
* HTTP 1.1 or later with persistent connection, pipelining supported
< HTTP/1.1 404 Not Found
* Server Apache-Coyote/1.1 is not blacklisted
< Server: Apache-Coyote/1.1
< Content-Length: 0
< Date: Wed, 16 Dec 2015 17:33:37 GMT
<
* STATE: PERFORM => DONE handle 0x6000572d0; line 1632 (connection #0)
* Curl_done
* Connection #0 to host localhost left intact

So it's always a 404. Unless I do have such an /error resource, then what? what am I supposed to return? All I have at that point is a GET request to /error. And I don't want those extra requests consuming resources and polluting my logs.

What am I missing? And if nothing, what should I do with my exception handling?

Answer 1

You can set the Jersey property ServerProperties.RESPONSE_SET_STATUS_OVER_SEND_ERROR to true.

Whenever response status is 4xx or 5xx it is possible to choose between sendError or setStatus on container specific Response implementation. E.g. on servlet container Jersey can call HttpServletResponse.setStatus(...) or HttpServletResponse.sendError(...).

Calling sendError(...) method usually resets entity, response headers and provide error page for specified status code (e.g. servlet error-page configuration). However if you want to post-process response (e.g. by servlet filter) the only way to do it is calling setStatus(...) on container Response object.

If property value is true the method Response.setStatus(...) is used over default Response.sendError(...).

Type of the property value is boolean. The default value is false.

You can set Jersey property simply by calling property(key, value) in your ResourceConfig subclass constructor.