package org.activiti.rest.exception;

import org.activiti.engine.ActivitiIllegalArgumentException;
import org.activiti.engine.ActivitiObjectNotFoundException;
import org.activiti.engine.ActivitiTaskAlreadyClaimedException;
import org.springframework.http.HttpStatus;
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;

/**
 * From http://spring.io/blog/2013/11/01/exception-handling-in-spring-mvc
 * 
 * @author Tijs Rademakers
 */
@ControllerAdvice
public class ExceptionHandlerAdvice {
  
  @ResponseStatus(HttpStatus.UNSUPPORTED_MEDIA_TYPE) // 415
  @ExceptionHandler(ActivitiContentNotSupportedException.class)
  @ResponseBody
  public ErrorInfo handleNotSupported(ActivitiContentNotSupportedException e) {
    return new ErrorInfo("Content is not supported", e);
  }

  @ResponseStatus(HttpStatus.CONFLICT) // 409
  @ExceptionHandler(ActivitiConflictException.class)
  @ResponseBody
  public ErrorInfo handleConflict(ActivitiConflictException e) {
    return new ErrorInfo("Conflict", e);
  }
  
  @ResponseStatus(HttpStatus.CONFLICT) // 409
  @ExceptionHandler(ActivitiTaskAlreadyClaimedException.class)
  @ResponseBody
  public ErrorInfo handleTaskAlreadyClaimed(ActivitiTaskAlreadyClaimedException e) {
    return new ErrorInfo("Task was already claimed", e);
  }
  
  @ResponseStatus(HttpStatus.NOT_FOUND)  // 404
  @ExceptionHandler(ActivitiObjectNotFoundException.class)
  @ResponseBody
  public ErrorInfo handleNotFound(ActivitiObjectNotFoundException e) {
      return new ErrorInfo("Not found", e);
  }
  
  @ResponseStatus(HttpStatus.FORBIDDEN)  // 403
  @ExceptionHandler(ActivitiForbiddenException.class)
  @ResponseBody
  public ErrorInfo handleForbidden(ActivitiForbiddenException e) {
      return new ErrorInfo("Forbidden", e);
  }
  
  @ResponseStatus(HttpStatus.BAD_REQUEST) // 400
  @ExceptionHandler(ActivitiIllegalArgumentException.class)
  @ResponseBody
  public ErrorInfo handleIllegal(ActivitiIllegalArgumentException e) {
    return new ErrorInfo("Bad request", e);
  }
  
  // Fall back
  
  @ResponseStatus(HttpStatus.INTERNAL_SERVER_ERROR)  // 500
  @ExceptionHandler(Exception.class)
  @ResponseBody
  public ErrorInfo handleOtherException(Exception e) {
  	return new ErrorInfo("Internal server error", e);
  }
  
}

package org.activiti.rest.exception;

import org.activiti.engine.ActivitiIllegalArgumentException;
import org.activiti.engine.ActivitiObjectNotFoundException;
import org.activiti.engine.ActivitiTaskAlreadyClaimedException;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.http.HttpStatus;
import org.springframework.http.converter.HttpMessageConversionException;
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;

/**
 * From http://spring.io/blog/2013/11/01/exception-handling-in-spring-mvc
 * 
 * @author Tijs Rademakers
 */
@ControllerAdvice
public class ExceptionHandlerAdvice {
	
	private static final Logger LOGGER = LoggerFactory.getLogger(ExceptionHandlerAdvice.class);
  
  @ResponseStatus(HttpStatus.UNSUPPORTED_MEDIA_TYPE) // 415
  @ExceptionHandler(ActivitiContentNotSupportedException.class)
  @ResponseBody
  public ErrorInfo handleNotSupported(ActivitiContentNotSupportedException e) {
    return new ErrorInfo("Content is not supported", e);
  }

  @ResponseStatus(HttpStatus.CONFLICT) // 409
  @ExceptionHandler(ActivitiConflictException.class)
  @ResponseBody
  public ErrorInfo handleConflict(ActivitiConflictException e) {
    return new ErrorInfo("Conflict", e);
  }
  
  @ResponseStatus(HttpStatus.CONFLICT) // 409
  @ExceptionHandler(ActivitiTaskAlreadyClaimedException.class)
  @ResponseBody
  public ErrorInfo handleTaskAlreadyClaimed(ActivitiTaskAlreadyClaimedException e) {
    return new ErrorInfo("Task was already claimed", e);
  }
  
  @ResponseStatus(HttpStatus.NOT_FOUND)  // 404
  @ExceptionHandler(ActivitiObjectNotFoundException.class)
  @ResponseBody
  public ErrorInfo handleNotFound(ActivitiObjectNotFoundException e) {
      return new ErrorInfo("Not found", e);
  }
  
  @ResponseStatus(HttpStatus.FORBIDDEN)  // 403
  @ExceptionHandler(ActivitiForbiddenException.class)
  @ResponseBody
  public ErrorInfo handleForbidden(ActivitiForbiddenException e) {
      return new ErrorInfo("Forbidden", e);
  }
  
  @ResponseStatus(HttpStatus.BAD_REQUEST) // 400
  @ExceptionHandler(ActivitiIllegalArgumentException.class)
  @ResponseBody
  public ErrorInfo handleIllegal(ActivitiIllegalArgumentException e) {
    return new ErrorInfo("Bad request", e);
  }
  
  @ResponseStatus(HttpStatus.BAD_REQUEST) // 400
  @ExceptionHandler(HttpMessageConversionException.class)
  @ResponseBody
  public ErrorInfo handleBadMessageConversion(HttpMessageConversionException e) {
    return new ErrorInfo("Bad request", e);
  }
  
  // Fall back
  
  @ResponseStatus(HttpStatus.INTERNAL_SERVER_ERROR)  // 500
  @ExceptionHandler(Exception.class)
  @ResponseBody
  public ErrorInfo handleOtherException(Exception e) {
  	LOGGER.error("Unhandled exception", e);
  	return new ErrorInfo("Internal server error", e);
  }
  
}

Fix failing QA