ControllerErrorAdvice.java

package com.codesoom.assignment.controllers;

import com.codesoom.assignment.dto.ErrorResponse;
import com.codesoom.assignment.errors.*;
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;

import javax.validation.ConstraintViolation;
import javax.validation.ConstraintViolationException;
import java.util.Set;

@ResponseBody
@ControllerAdvice
public class ControllerErrorAdvice {
    @ResponseStatus(HttpStatus.NOT_FOUND)
    @ExceptionHandler(ProductNotFoundException.class)
    public ErrorResponse handleProductNotFound() {
        return new ErrorResponse("Product not found");
    }

    @ResponseStatus(HttpStatus.NOT_FOUND)
    @ExceptionHandler(UserNotFoundException.class)
    public ErrorResponse handleUserNotFound() {
        return new ErrorResponse("User not found");
    }

    @ResponseStatus(HttpStatus.BAD_REQUEST)
    @ExceptionHandler(UserEmailDuplicationException.class)
    public ErrorResponse handleUserEmailIsAlreadyExisted() {
        return new ErrorResponse("User's email address is already existed");
    }

    @ResponseStatus(HttpStatus.BAD_REQUEST)
    @ExceptionHandler(LoginFailException.class)
    public ErrorResponse handleLoginFailException() {
        return new ErrorResponse("Log-in failed");
    }

    @ResponseBody
    @ResponseStatus(HttpStatus.BAD_REQUEST)
    @ExceptionHandler(ConstraintViolationException.class)
    public ErrorResponse handleConstraintValidateError(
            ConstraintViolationException exception
    ) {
        String messageTemplate = getViolatedMessage(exception);
        return new ErrorResponse(messageTemplate);
    }

    @ResponseBody
    @ResponseStatus(HttpStatus.FORBIDDEN)
    @ExceptionHandler(UserNoPermission.class)
    public ErrorResponse handleUserNoPermission(UserNoPermission exception) {
        return new ErrorResponse(exception.getMessage());
    }

    private String getViolatedMessage(ConstraintViolationException exception) {
        String messageTemplate = null;
        Set<ConstraintViolation<?>> violations = exception.getConstraintViolations();
        for (ConstraintViolation<?> violation : violations) {
            messageTemplate = violation.getMessageTemplate();
        }
        return messageTemplate;
    }
}