问题
I'm using Spring Boot 1.5.4 with Spring JPA, Spring Data REST, HATEOAS... I'm looking for a best practice (Spring way) to customize exceptions Spring Data REST is managing adding the i18n support.
I looked at the class MessageException (https://github.com/spring-projects/spring-data-rest/blob/master/spring-data-rest-webmvc/src/main/java/org/springframework/data/rest/webmvc/support/ExceptionMessage.java) as start point.
A typical Spring Data REST exception is very nice:
{
"timestamp": "2017-06-24T16:08:54.107+0000",
"status": 500,
"error": "Internal Server Error",
"exception": "org.springframework.dao.InvalidDataAccessApiUsageException",
"message": "org.hibernate.TransientPropertyValueException: Not-null property references a transient value - transient instance must be saved beforeQuery current operation : com.test.server.model.workflows.WorkSession.checkPoint -> com.test.server.model.checkpoints.CheckPoint; nested exception is java.lang.IllegalStateException: org.hibernate.TransientPropertyValueException: Not-null property references a transient value - transient instance must be saved beforeQuery current operation : com.test.server.model.workflows.WorkSession.checkPoint -> com.test.server.model.checkpoints.CheckPoint",
"path": "/api/v1/workSessions/start"
}
What I'm trying to do is:
- Localize error and message fields (i18n)
- possibly change the message text to something else (always localized)
I didn't find any reference in Spring Data REST doc about how to customize or localize exception (https://docs.spring.io/spring-data/rest/docs/current/reference/html/). I hope there is a elegant way to do that.
I added in my WebMvcConfigurerAdapter this:
@Bean
public LocaleResolver localeResolver() {
return new SmartLocaleResolver();
}
public class SmartLocaleResolver extends CookieLocaleResolver {
@Override
public Locale resolveLocale(HttpServletRequest request) {
String acceptLanguage = request.getHeader("Accept-Language");
if (acceptLanguage == null || acceptLanguage.trim().isEmpty()) {
return super.determineDefaultLocale(request);
}
return request.getLocale();
}
}
@Bean
public ResourceBundleMessageSource messageSource() {
ResourceBundleMessageSource source = new ResourceBundleMessageSource();
source.setBasenames("i18n/messages"); // name of the resource bundle
source.setUseCodeAsDefaultMessage(true);
return source;
}
I guess I could be able to intercept exceptions in this way:
@ControllerAdvice(annotations = RepositoryRestController.class)
public class GenericExceptionHandler {
@ExceptionHandler
public ResponseEntity handle(Exception e, Locale locale) {
//missing part...
return new ResponseEntity(exceptionMessageObject, new HttpHeaders(), httpStatus);
}
Is there a way to put all together using Spring best practices?
回答1:
@ControllerAdvice(annotations = RepositoryRestController.class)
public class GenericExceptionHandler {
@Autowired
private MessageSource messageSource;
@ExceptionHandler
//if you don't use Exception e in method you can remove it , live only Locale
public ResponseEntity handle(Exception e, Locale locale) {
String errorMessage = messageSource.getMessage(
"error.message", new Object[]{},locale);
//set message or return it instead of exceptionMessageObject
exceptionMessageObject.setMessage(exceptionMessageObject);
return new ResponseEntity(exceptionMessageObject,
new HttpHeaders(), httpStatus);
}
see spring doc 7.15.1 Internationalization using MessageSource
" how I should create exceptionMessageObject to be like the one Spring Data REST creates? "
create you own error wraper like :
public class CustomError {
private HttpStatus status;
private String message;
private Exception originalException;//if you need it
// getter setter
}
"How to have different messages for different exceptions? Should I create a long if else chain checking the class of the exception? "
create resolver ,
private String resolveExceptionToMessage(Exception exceptio){
//or put in map<Exceptio,String error.message.type1>
// String errorCode = map.get(excptio);
//eturn messageSource.getMessage(errorCode , new Object[]{},locale);
if(exceptio instanceof ....){
return messageSource.getMessage("error.message.type1", new Object[]{},locale);
}
return "";
}
or use methods with @ExceptionHandler({ CustomException1.class }) , @ExceptionHandler({ CustomException1.class }).... and do put in each method just errror.code , all other part are similar
@ExceptionHandler({ CustomException1.class})
public ResponseEntity handleException1() {
return createError(code for this exceptio 1);
}
@ExceptionHandler({ CustomException2.class})
public ResponseEntity handleException2() {
return createError(code for this exceptio 2);
}
private ResponseEntity createError(String errorCode ) {
CustomError customError = new CustomError();
customError.setHttpStatus(HttpStatus.BAD_REQUEST);
String errorMessage = messageSource.getMessage(
errorCode , new Object[]{},locale);
customError.setMessage(errorMessage );
customError.setOriginalException(e);
return new ResponseEntity<Object>(customError, new HttpHeaders(),
customError.getStatus());
}
How set httpStatus? I would like use the default status Spring Data REST use for commons exceptions...
public ResponseEntity handle(Exception e, Locale locale) {
CustomError customError = new CustomError();
customError.setHttpStatus(HttpStatus.BAD_REQUEST);
customError.setMessage(resolveExceptionToMessage(e));
customError.setOriginalException(e);
return new ResponseEntity<Object>(customError, new HttpHeaders(),
customError.getStatus());
}
回答2:
Thanks to @sbjavateam for his reply. I want to post another way to do this thing just for completeness. The comment is not ideal to write everything, so I'm replying here.
Instead to use a @ControllerAdvice, a simpler solution is customize the ErrorAttributes:
public class CustomErrorAttributes extends DefaultErrorAttributes {
private Logger log = LogManager.getLogger();
@Autowired
private MessageSource messageSource;
@Override
public Map<String, Object> getErrorAttributes(RequestAttributes requestAttributes, boolean includeStackTrace) {
Locale locale = LocaleContextHolder.getLocale();
Map<String, Object> errorAttributes = super.getErrorAttributes(requestAttributes, includeStackTrace);
Throwable throwable = getError(requestAttributes);
/**
* Adding the cause if present
*/
if (throwable != null && throwable.getCause() != null) {
Throwable cause = throwable.getCause();
Map<String, Object> causeErrorAttributes = new HashMap<>();
causeErrorAttributes.put("exception", cause.getClass().getName());
causeErrorAttributes.put("message", cause.getMessage());
errorAttributes.put("cause", causeErrorAttributes);
}
/**
* Customizing the message for every exception
*/
if (throwable instanceof InvalidDataAccessApiUsageException) {
String message = messageSource.getMessage(throwable.getClass().getName(), new Object[] {}, locale);
errorAttributes.put("message", message);
}
return errorAttributes;
}
}
Of course you have to define this bean in your WebMvcConfigurerAdapter or add the @Component. In the first case you need to do:
@EnableHypermediaSupport(type = { HypermediaType.HAL })
public class WebMvcConfiguration extends WebMvcConfigurerAdapter {
@Bean
public CustomErrorAttributes myCustomErrorAttributes() {
return new CustomErrorAttributes();
}
@Bean
public MessageSource messageSource() {
ReloadableResourceBundleMessageSource messageSource = new ReloadableResourceBundleMessageSource();
messageSource.setBasenames("classpath:/i18n/messages");
messageSource.setDefaultEncoding("UTF-8");
messageSource.setUseCodeAsDefaultMessage(true);
messageSource.setCacheSeconds((int) TimeUnit.HOURS.toSeconds(1));
messageSource.setFallbackToSystemLocale(false);
return messageSource;
}
}
In this way is very easy customize the exception and you can just override values rather than create a new custom exception object.
回答3:
In my project I use CustomErrorController. This controller caches all errors including 404. Example:
@Controller
@RequestMapping("${error.path:/error}")
public class CustomErrorController implements ErrorController {
@Value("${error.path:/error}")
private String errorPath;
@Override
public String getErrorPath() {
return this.errorPath;
}
@RequestMapping
@ResponseBody
public ResponseEntity<Object> error(HttpServletRequest request) {
HashMap<String, Object> response = new HashMap<String, Object>();
// your code here...
return new ResponseEntity<Object>(response, status);
}
}
来源：https://stackoverflow.com/questions/44738565/handling-custom-exceptions-i18n-with-spring-data-rest