I am implementing all the methods of ResponseEntityExceptionHandler because i don't want Spring to send any standard error responses towards the client. There are two seemingly similar methods that confuse me a bit. Namely handleExceptionInternal and handleException. These are the definitions of both methods according to the official documentation.
handleException(Exception ex, WebRequest request)
Provides handling for standard Spring MVC exceptions.
handleExceptionInternal(Exception ex, Object body, HttpHeaders headers, HttpStatus status, WebRequest request)
A single place to customize the response body of all exception types.
I find these explanations a bit vague. What can be considered 'standard spring mvc exceptions' for example? And should handleExceptionInternal be considered like a 'default' handler method that is used when none of the other methods can catch the spring exception? Please correct me if i'm wrong.
Thank you
handleException method is a common exception handler for standard spring mvc exceptions. Its main task is it maps these exception to respective status code as per http response code convention, which most likely you are not going to change.
e.g.
HttpRequestMethodNotSupportedException -> 405
HttpMediaTypeNotSupportedException -> 415
NoHandlerFoundException -> 404
All these exceptions are handled in their specific handler methods handle{ExceptionName} so that for some reason, if you want to change the status code (or add response body for detailed info), you can do so by overriding specific handler. All these handlers further delegate to handleExceptionInternal.
One thing you have noticed each handle{ExceptionName} methods pass body as null to handleExceptionInternal. These methods just return the status code with no body which doesn't give you more details about the error.
A common practice is to return a custom error response body with details so that your api consumers know the exact error cause. This is the place you can inject your custom body by creating an Error object. A simple error message would look like.
public class ApiError {
private final int status;
private final int message;
public ApiError(int status, int message) {
this.status = status;
this.message = message;
}
// getters
}
And you can override handleExceptionInternal method as:
#Override
protected ResponseEntity<Object> handleExceptionInternal(Exception ex, Object body, HttpHeaders headers, HttpStatus status, WebRequest request) {
ApiError error = new ApiError(status.value(), ex.getMessage());
return super.handleExceptionInternal(ex, error, headers, status, request);
}
Summary
If handleException wouldn't there, then you need to manually map each exceptions to respective error code. If handleExceptionInternal were missing then to inject error body you would need to override each handle{Exception} methods.
Update
RFC for http status code definition.
Related
Is it possible to fetch RequestBody from WebRequest object?
I am handling exceptions from controller advice so would like to handle the request as well to send data back in response. I saw its documentation what I understood is we can fetch query params from that object for GET request. If there is any other approach which I missed can somebody please help.
#NonNull
#Override
protected ResponseEntity<Object> handleHttpMessageNotReadable(
#Nullable HttpMessageNotReadableException ex,
#Nullable HttpHeaders headers,
HttpStatus status,
#Nullable WebRequest request) {
//handling of input request we got from Spring Controller
}
Try passing InputStream / Reader for access to the request's content. This will be the raw InputStream/Reader as exposed by the Servlet API. and/or response objects (typically from the Servlet API) as per official documentation.
#NonNull
#Override
protected ResponseEntity<Object> handleHttpMessageNotReadable(
#Nullable HttpMessageNotReadableException ex,
#Nullable HttpHeaders headers,
HttpStatus status,
#Nullable WebRequest request,
InputStream requestContent
) {
//handling of input request we got from Spring Controller
}
When exception occurs in your controller - catch it and extract any and all info you want. Create your own class - Lets say CustomErrorInfo and fill it with all the info you want and throw your own custom exception that will contain your CustomErrorInfo class and the original exception. Than in your controller advice add method that would handle your custom exception and there you will have an access to your CustomErrorInfo class instance thast you filled when exception occurred
I have two REST API's GET POST
When any Exception is thrown inside the method, Exception handler is working fine.
But if i use malformed REST api uri then it only shows 400 Bad Request without going to Exception Handler.
Eg.
If I hit http://localhost:8080/mypojoInteger/abc, it fails to parse string into Integer and hence I am expecting it to go to ExceptionHandler.
It does not go to Exception Handler, Instead I only see 400 Bad Request.
It works fine and goes to Exception Handler when any Exception is thrown inside the GET/POST method.
For eg: It works fine and goes to Exception Handler if I use 123 in path variable
http://localhost:8085/mypojoInteger/123
And change getData method to
#GetMapping("/mypojoInteger/{sentNumber}")
public void getData(#PathVariable("sentNumber") Integer sentNumber) {
throw new NumberFormatException("Exception");
}
NOTE: Same issue is with POST request also.
GET:
#GetMapping("/mypojoInteger/{sentNumber}")
public void getData(#PathVariable("sentNumber") Integer sentNumber) {
//some code
}
POST:
public void postData(#RequestBody MyPojo myPojo) {
//some code
}
Controller Advice class:
#ControllerAdvice
public class CustomGlobalExceptionHandler extends ResponseEntityExceptionHandler {
#ExceptionHandler(NumberFormatException.class)
protected ResponseEntity<Object> handleEntityNotFound(
NumberFormatException ex) {
// some logic
}
}
How can I handle Exception when it fails to bind String to Integer in REST API uri itself??
EDIT: My Requirement is I should handle the overflow value of integer i.e, If a pass more than maximum value of Integer it must handle it rather than throwing NumberFormatException Stack Trace.
Eg: When i pass over flow value
POJO:
public class MyPojo extends Exception {
private String name;
private Integer myInt;
//getters/setter
}
{
"name":"name",
"myInt":12378977977987879
}
Without #ControllerAdvice it just shows the NumberFormatException StackTrace.
With #ControllerAdvice it just shows 400 bad request with no Response Entity.
I do not want this default stacktrace/400 bad request in case of this scenario
but I want to show my custom message.
The reason that i see is that, because since your request itself is malformed-> the method body never gets executed - hence the exception never occurs because it is only meant to handle the error within the method . It is probably a better design choice for you to form a proper request body rather than allowing it to execute any method so you know the problem before hand.
The issue is because Integer object is not sent as a valid request parameter, example of request: 5 if you send String an exception will be thrown directly. If you want to check if it is a String or Integer you might change your code by following this way:
#GetMapping("/mypojoInteger/{sentNumber}")
public void getData(#PathVariable("sentNumber") Object sentNumber) {
if (!(data instanceof Integer)) {
throw new NumberFormatException("Exception");
}
}
This should work on your example.
Solution:
I found out that I need to handle Bad Request.
So, I have override
#Override
protected ResponseEntity<Object> handleHttpMessageNotReadable(HttpMessageNotReadableException ex, HttpHeaders headers, HttpStatus status, WebRequest request) {
//Handle Bad Request
}
I have implemented a Spring Rest Controller that streams back large files using the StreamingResponseBody. However, these files are coming from another system and there is the potential for something to go wrong while streaming them back. When this occurs I am throwing a custom Exception (MyException). I am handling the exception in an #ExceptionHandler implementation which is below. I am attempting to set the response httpstatus and error message but I am always receiving http status 406. What is the proper way to handle errors/exceptions while returning a StreamingResponseBody?
#ExceptionHandler(MyException.class)
public void handleParsException( MyException exception, HttpServletResponse response) throws IOException
{
response.sendError(HttpStatus.INTERNAL_SERVER_ERROR.value(),exception.getMessage());
}
You should handle all errors in the same way. There are many options.
I prefer next:
Controller Advice
It is a good idea to have an entity to send a generic error response, an example:
public class Error {
private String code;
private int status;
private String message;
// Getters and Setters
}
Otherwise, to handle exceptions you should create a class annotated with #ControllerAdvice and then create methods annotated with #ExceptionHandler and the exception or exceptions (it could be more than one) you want to handle. Finally return ResponseEntity<Error> with the status code you want.
public class Hanlder{
#ExceptionHandler(MyException.class)
public ResponseEntity<?> handleResourceNotFoundException(MyException
myException, HttpServletRequest request) {
Error error = new Error();
error.setStatus(HttpStatus.CONFLICT.value()); //Status you want
error.setCode("CODE");
error.setMessage(myException.getMessage());
return new ResponseEntity<>(error, null, HttpStatus.CONFLICT);
}
#ExceptionHandler({DataAccessException.class, , OtherException.class})
public ResponseEntity<?> handleResourceNotFoundException(Exception
exception, HttpServletRequest request) {
Error error = new Error();
error.setStatus(HttpStatus.INTERNAL_ERROR.value()); //Status you want
error.setCode("CODE");
error.setMessage(myException.getMessage());
return new ResponseEntity<>(error, null, HttpStatus.INTERNAL_ERROR);
}
}
Other ways:
Annotate exception directly
Other way is annotating directly the excetion with the status and the reason to return:
#ResponseStatus(value=HttpStatus.CONFLICT, reason="Error with StreamingResponseBody")
public class MyError extends RuntimeException {
// Impl ...
}
Exception Handler in a specific controller
Use a method annotated with #ExceptionHandler in a method of a #Controller to handle #RequestMapping exceptions:
#ResponseStatus(value=HttpStatus.CONFLICT,
reason="Error with StreamingResponse Body")
#ExceptionHandler(MyError.class)
public void entitiyExists() {
}
I figured the problem out. The client was only accepting the file type as an acceptable response. Therefore, when returning an error in the form of an html page I was getting httpstatus 406. I just needed to tell the client to accept html as well to display the message.
When a client request for a resource producing application/json content with Accept Header of application/xml. The request fails with HttpMediaTypeNotAcceptableException exception and is wrapped into error message body in the response entity object by using exception handler annotation as mentioned in below code. However, we receive HttpMediaTypeNotAcceptableException again when return values are written to the response with HttpMessageConverter. It is because it checks the producible content type for the response with the acceptable request type, but this is exactly something we are trying to communicate to the client using error message. How do I workaround this issue ? Btw, all the other exceptions are parsing fine to error message. Please advise.
#ControllerAdvice
public class RestExceptionHandler extends ResponseEntityExceptionHandler {
#Override
protected ResponseEntity<Object> handleExceptionInternal(Exception ex, Object body,
HttpHeaders headers, HttpStatus status, WebRequest request) {
// Setting the response content type to json
headers.setContentType(MediaType.APPLICATION_JSON);
return ResponseEntity.status(status).headers(headers).body(body);
}
}
A few options come to my mind. One is that your controller method produces all content types and then you throw an exception in your method if the content type is not the one you are expecting, then the exception handler can take this exception and transform it. This is the only one that works with exception handlers, as exception handlers only deal with exceptions produced in the controller method.
The other options are:
Use an interceptor (but I'm not sure if this will work, as Spring might try to resolve first the controller method rather than invoking the interceptors).
Extend RequestMappingHandlerMapping to call the exception handler if it doesn't find a suitable method. You'll probably need to override the method handleNoMatch. In there you'll need to get a reference to the list of HandlerExceptionResolver
The first one is the simplest to understand, and the latest one might be the most 'extensible', but it also requires some understanding of the internals of Spring.
Resolved by setting different content negotiation strategy FixedContentNegotiationStrategy for ExceptionHandlerExceptionResolver and HeaderContentNegotiationStrategy for RequestResponseBodyMethodProcessor.
I have been using a serialized enum-based response (enum annotated with jackson #JsonFormat(shape = Shape.OBJECT) to standardize the error messages in my exception handler class and faced the same issue when it caught with a HttpMediaTypeNotAcceptableException.
The workaround is to set the media type you expect to return directly to the builder method available in the ResponseEntity.
The below code works fine for me.
#ExceptionHandler(HttpMediaTypeNotAcceptableException.class)
public final ResponseEntity<ResponseMessagesEnum> handleHttpMediaTypeNotAcceptableException(
HttpMediaTypeNotAcceptableException e, HttpServletRequest request) {
logger.error("No acceptable representation found for [{}] | supported {}", request.getHeader("Accept"), e.getSupportedMediaTypes());
return ResponseEntity.status(HttpStatus.BAD_REQUEST).contentType(MediaType.APPLICATION_JSON)
.body(ResponseMessagesEnum.EX_001);
}
I want to handle exceptions so the URL information is automatically shown to the client. Is there an easy way to do this?
<bean id="outboundExceptionAdapter" class="org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerExceptionResolver">
<!-- what property to set here? -->
</bean>
You have two choices:
Spring Reference 15.9.1 HandlerExceptionResolver
Spring HandlerExceptionResolvers ease the pain of unexpected
exceptions that occur while your request is handled by a controller
that matched the request. HandlerExceptionResolvers somewhat resemble
the exception mappings you can define in the web application
descriptor web.xml. However, they provide a more flexible way to
handle exceptions. They provide information about which handler was
executing when the exception was thrown. Furthermore, a programmatic
way of handling exceptions gives you more options for responding
appropriately before the request is forwarded to another URL (the same
end result as when you use the servlet specific exception mappings).
The HandlerExceptionResolver has one method, containing everything you need:
HandlerExceptionResolver.resolveException(HttpServletRequest request,
HttpServletResponse response,
Object handler, Exception ex)
Or if you need different handlers for different controllers: Spring Reference Chapter 15.9.2 #ExceptionHandler
#ExceptionHandler(IOException.class)
public String handleIOException(IOException ex, HttpServletRequest request) {
return "every thing you asked for: " + request;
}
Short question short answer
I'm doing the following trick:
#ExceptionHandler(Exception.class)
public ModelAndView handleMyException(Exception exception) {
ModelAndView mv = new ModelAndView("redirect:errorMessage?error="+exception.getMessage());
return mv;
}
#RequestMapping(value="/errorMessage", method=RequestMethod.GET)
#Responsebody
public String handleMyExceptionOnRedirect(#RequestParamter("error") String error) {
return error;
}
Works flawless.