Return a custom error message for 400 requests that don't hit the controller

Question

I need to be able to return a custom error message for requests that are Bad Requests, but don't hit a controller (ex. Having bad JSON). Does anyone have any idea how to go about this? I tried the @ExceptionHandler annotation to no avail.

Any help would be appreciated.

Answer 1

Since Spring 3.2 you can add a ControllerAdvice like this

import org.springframework.http.HttpStatus;
import org.springframework.http.converter.HttpMessageNotReadableException;
import org.springframework.web.bind.annotation.ControllerAdvice;
import org.springframework.web.bind.annotation.ExceptionHandler;
import org.springframework.web.bind.annotation.ResponseBody;
import org.springframework.web.bind.annotation.ResponseStatus;

@ControllerAdvice
public class BadRequestHandler {

    @ResponseStatus(HttpStatus.OK)
    @ExceptionHandler(HttpMessageNotReadableException.class)
    @ResponseBody
    public ErrorBean handleHttpMessageNotReadableException(HttpMessageNotReadableException e) {
        ErrorBean errorBean = new ErrorBean();
        errorBean.setMessage(e.getMessage());
        return errorBean;
    }

    class ErrorBean {
        private String message;

        public String getMessage() {
            return message;
        }

        public void setMessage(String message) {
            this.message = message;
        }
    }
}

In handleHttpMessageNotReadableException, which is annotated with @ExceptionHandler(HttpMessageNotReadableException.class), you can handle the exception and render a custom response. In this case a ErrorBean becomes populated and return to the client. If Jackson is available on classpath and Content-Type was set to application/json by the client, this ErrorBean gets returned as json.