java 8, spring, rest
I am trying to capture the Response that comes from exception mapper, and do something with it in the caller which throws the exception. Thanks.
#Provider
public class CustomerExceptionHandler implements ExceptionMapper<CustomerException>
{
#Override
public Response toResponse(CustomerException exception)
{
return Response.status(Status.BAD_REQUEST).entity(CustomerException.getMessage()).build();
}
}
public class CustomerException extends Exception implements Serializable
{
private static final long serialVersionUID = 1L;
public CustomerException() {
super();
}
public CustomerException(String msg) {
super(msg);
}
public CustomerException(String msg, Exception e) {
super(msg, e);
}
}
public class ExceptionDemo{
public void getExceptionResponse(){
//do something
throw new CustomerException("Something is wrong");// CustomerExceptionHandler is going to return me a Response, how can I capture the response here?
//capture response and do something with it
}
}
I'm not sure ExceptionMappers work in the way you think they do.
When some code in the endpoint throws an exception, and this exception percolates all the way out of the endpoint and back into the container itself (Spring in this case), then the registered ExceptionMappers are consulted to see if they match the thrown exception, and the relevant one's public Response toResponse(T e) {} method is called to transform it into a Response.
The ExceptionMapper doen't get called as part of your endpoint code, and you won't be able to take action based on its resultant Response because it hasn't yet been called. You just need to throw the exception out of the endpoint.
Related
I have a feign client like this
#FeignClient(name = "client")
public interface SomeClient {
#RequestLine("GET /?q={q}")
void execute(URI baseUrl, #Param("q") String q) throws SomeExceptionInMyCode;
}
Looking to this throws SomeExceptionInMyCode I'm asking myself when this exception will be thrown. There is no configuration for client defined, no error decoder. Exception looks like this.
public class SomeExceptionInMyCode extends Exception{
private final int statusCode;
private final String reason;
private final String body;
// getters and setters
}
Will there be an automatic attempt to decode HTTP response to this exception in case of failure? Or throws SomeExceptionInMyCode is useless and can be removed without any impact.
I searched inside my code and this exception is never created.
Will there be an automatic attempt to decode http response to this exception in case of failure?
Nope, it doesn't work like this and the SomeExceptionMyCode will not be thrown. The throws clause is useless. Even if the endpoint throws this exception from its implementation, it will be wrapped as a cause of FeignException.
The correct way to handle feign client exceptions is using Custom exception handling implementing ErrorDecoder:
public class StashErrorDecoder implements ErrorDecoder {
#Override
public Exception decode(String methodKey, Response response) {
if (response.status() >= 400 && response.status() <= 499) {
// return 4XX exception
}
if (response.status() >= 500 && response.status() <= 599) {
// return 5XX exception
}
}
}
At this point you can perform the custom exception creation and rethrowing.
An alternative solution is to use Spring-alike #RestControllerAdvice:
#RestControllerAdvice
public class ExceptionHandler {
#ExceptionHandler(FeignException.class)
public String handleFeignStatusException(FeignException e, HttpServletResponse response) {
// ...
}
}
What if the StashErrorDecoder throws a checked exception? That is allowed. In this case the throws clause in the interface surely helps. This way you can catch and handle the exception thrown by Feign. At least it should work this way.
I have a service class with #Async method and If it's calling method throwing any exception then the #ControllerAdvice will not call for global exception handling. But for other classes and services it will call advice and sending email properly.
#Service
public class FileScanServiceImpl implements FileScanService {
#Override
#Async
public void scanFileScheduler() throws MQException {
try{
messageProducer.putFileNameToMQ(fileName);
} catch (Exception e) {
ExceptionUtility.handleException(e, currentFile);
}
}
The ExceptionUtility is used for checking instance on exception and doing some functionality there and throwing custom exception.
public static void handleException(Exception e throws MQException {
String errMsg = "";
if (e instanceof MQException) {
// some functionality
throw new MQException(subject, errMsg);
}
}
And this is my #ControlleAdvice
#ControllerAdvice
public class GlobalExceptionHandler {
#ExceptionHandler(MQException.class)
#ResponseBody
public void handleMQException(HttpServletRequest request, MQException ex) {
// send email
}
}
It there any solution for #Async which will call #ControllerAdvice for global exception, also the existing functionality will not break.
#ExceptionHandler was created to catch only "synchronous exceptions". If it had the ability to catch exceptions from asynchronous threads, then when several threads start and if any of them fail, the request to the server would be interrupted completely and the system could remain in an inconsistent state (due to many other active threads generated by this request)
For handling asynchronous exceptions Spring has the AsyncUncaughtExceptionHandler interface:
public class YourAsyncExceptionHandler implements AsyncUncaughtExceptionHandler {
#Override
public void handleUncaughtException(Throwable ex, Method method, Object... params) {
// Your exception handling logic
}
}
More information can be found here in the Exceptions section: https://www.baeldung.com/spring-async
I'm new to jersey, and I want to throw a ConflictException(Custom) in my Service,
and catch it to give a response.
Below is my code..
public class ConflictException extends ClientErrorException {
public ConflictException() {
super(Response.Status.CONFLICT); // 409
}
}
Then I want to use a ExceptionMapper to send a proper Response.
#Provider
public class ConflictExceptionMapper implements ExceptionMapper<ConflictException> {
#Override
public Response toResponse(ConflictException exception) {
return Response.status(Response.Status.CONFLICT).entity(new ResponseMessage( Collections.emptyList(), OperationResultStatus.Conflict,
exception.getMessage())).build();
}
}
Somehow this Mapper is not being triggered.
What am I doing wrong....
Update!!! Snipped of my main class included.
final ResourceConfig rc = new ResourceConfig().packages(packages)
// Now you can expect validation errors to be sent to the client.
.property(ServerProperties.BV_SEND_ERROR_IN_RESPONSE, true)
// #ValidateOnExecution annotations on subclasses won't cause errors.
.property(ServerProperties.BV_DISABLE_VALIDATE_ON_EXECUTABLE_OVERRIDE_CHECK, true)
// Further configuration of ResourceConfig.
//.property(ServerProperties.PROCESSING_RESPONSE_ERRORS_ENABLED, true)
.register(new ClassBinder())
.register(json)
.register(ConstraintViolationExceptionMapper.class)
.register(ConflictExceptionMapper.class);
So I am build an mvc application using Jersey. A method that accepts Path parameters (#PathParam).
If a custom exception is thrown (ExampleException) then a 404 Not Found response is returned using an exception mapper.
#Provider
public class ExampleExceptionMapper implements ExceptionMapper<ExampleException> {
#Override
public Response toResponse(ExampleException ex) {
return Response.status(Status.NOT_FOUND).entity("Not Found - " + ex.getMessage()).build();
}
}
However, I am implementing #FormParam's so a user POSTs to the server. The same exact exception is raised, but instead I should return a 400 Bad Request response. Without modifying the exception how would I be able to make the exception mapper return the proper response code?
Simplest way is create multiple ExceptionMappers, each for specific subclass of ExampleException.
But you want to have the same exception for both cases and decide whether to throw 404 for GET/PathParam and POST/FormParam, you can inject the request into the mapper and check what method it is:
#Provider
public class ExampleExceptionMapper implements ExceptionMapper<ExampleException> {
#Context Request request;
#Override
public Response toResponse(ExampleException ex) {
if ("POST".equals(requset.getMethod()))
return Response.status(Status.BAD_REQUEST).build();
else
return Response.status(Status.NOT_FOUND).entity("Not Found - " + ex.getMessage()).build();
}
}
If you want to decide by PathParams, you can inject UriInfo:
#Provider
public class ExampleExceptionMapper implements ExceptionMapper<ExampleException> {
#Context UriInfo info;
#Override
public Response toResponse(ExampleException ex) {
if (info.getPathParameters().isEmpty())) //please make better condition based on your needs
return Response.status(Status.BAD_REQUEST).build();
else
return Response.status(Status.NOT_FOUND).entity("Not Found - " + ex.getMessage()).build();
}
}
I am using Below Custom Exception class in my project
public class BadRequestException extends WebApplicationException {
private static final long serialVersionUID = 1L;
private String message;
public BadRequestException(String message) {
super();
this.message = message;
}
public String getMessage() {
return message;
}
public void setMessage(String message) {
this.message = message;
}
}
I have created a Mapper class also..
public class BadRequestExceptionMapper implements ExceptionMapper<BadRequestException> {
public Response toResponse(BadRequestException brexec) {
return Response.status(Response.Status.INTERNAL_SERVER_ERROR).entity(brexec.getResponse().getEntity()).type(MediaType.APPLICATION_JSON).build();
}
}
I am calling my service through a Servlet and the Exception is thrown by one of its method but i am not able to catch it in Servlet class.I have used below code to catch the exception..
try{
//Some Business logic then
service.path("restful").path("jwbservice/" + methodName + "/" + id).header("lid", lid).delete(String.class);
}
catch (BadRequestException ex) {
out.println(ex);
}
catch(Exception exe){
out.println(exe);
}
And the service method i have used this code in my Service class which will throw the exception.
#DELETE
#Path("/deleteLink/{id}")
#Produces(MediaType.APPLICATION_JSON)
public String deleteLink(#PathParam("id") int id, #HeaderParam("lid") String lid) throws BadRequestException {
if (id<= 0) {
throw new BadRequestException("Required Parameter: id");
}
//Some Business Logic
}
My Service throw the BadRequestException but in Servlet it is going to Exception catch not in BadRequestException Catch block.
Can any one know what i am doing wrong.
You will never get that exception in your servlet. This is because the servlet is effectively a REST client, and you are invoking a remote resource method to get some data. The resource call will either be successful (and some data will be mapped back), or it will fail and you will get no data (or a client side error).
On a side note, there is a problem in your server side exception mapper. You do not verify that the exception actually has a response entity before calling:
brexec.getResponse().getEntity()
In cases where the exception doesn't have a response the above code will cause a null pointer exception.
Some quick notes:
Exception classes already have a message property. You do not need to define an additional one
Your exception mapper needs to check for a non-existent response property, before trying to do something with it
The resource path in your servlet does not appear to match the server side path. I assume that is a copy/paste error.