JAX-RS supports handling custom exceptions — thrown in either EJBs or CID beans — to custom HTTP responses.
Assuming we have an “exceptional” EJB:
@Stateless
public class Hello {
public String greeting() {
if (new Random().nextBoolean())
throw new GreetingException("Could not greet");
return "hello";
}
}@ApplicationException
public class GreetingException extends RuntimeException {
public GreetingException(String message) {
super(message);
}
}The EJB is used in our JAX-RS resource:
@Path("hello")
public class HelloResource {
@Inject
Hello hello;
@GET
public String hello() {
return hello.greeting();
}
}Now to map the occurring exception to a custom HTTP response we can define a JAX-RS ExceptionMapper.
@Provider
public class GreetingExceptionMapper implements ExceptionMapper<GreetingException> {
@Override
public Response toResponse(GreetingException exception) {
return Response.status(Response.Status.CONFLICT)
.header("Conflict-Reason", exception.getMessage())
.build();
}
}The exception mapper is registered as a JAX-RS extension (by @Provider) and will handle any GreetingException thrown by a resource method.
The example will occasionally output HTTP 409 Conflict with header Conflict-Reason: Could not greet.
If a CDI managed bean is used instead of an EJB, the @ApplicationException annotation is not required.
| Published on Java Code Geeks with permission by Sebastian Daschner, partner at our JCG program. See the original article here: Handle custom exception types in JAX-RS Opinions expressed by Java Code Geeks contributors are their own. |
