How to catch Exception like in a FrontController in Spring - spring

Question

Basically every repository method can possibly throw a DataAccessException . A lot of exceptions inherit from DataAccessException. So maybe I will catch DuplicateKeyException or maybe DataIntegrityViolationException . But all the other say 40 - 50 exceptions I will not catch explicitly. Instead I will just catch DataAccessException . So why always catch DataAccessException ?? Instead I would prefer catching it just once. But how to do that in Spring. There is no Front Controller. There are just Controllers. So how should I catch it in a central place. The only place I know whould be start of Spring. But I don't think that works.
#SpringBootApplication
#EnableJpaRepositories
public class Application {
public static void main(String[] args) {
try{
SpringApplication.run(Application.class, args);
}
catch(DataAccessException e)
{
//Do your error handling here
}
}
}

Answer 1

You should catch the exceptions at the beans or controllers that has the code managing db access, you can catch and manage this each controller bu the better approach is to implement an exception handler as th guid is showing here https://www.baeldung.com/exception-handling-for-rest-with-spring

Answer 2

Simplified process:
The run method call starts an embadded web server (and the whole spring infrastructure). So actually for example if you try to print out something after run call, it would not appear on the console.
The webserver runs and dispatch your requests in different threads. So the exception will happen on that threads. Spring use lot of exception handlers etc in the background.
So it more complicated in the reality. But you may see that this is not a simple, single threaded application.
The previous answer shows how to handle the exceptions in central place. For simple mvc application, I suggest to use #ControllerAdvice

Answer 3

To catch the exceptions in one central place you can use a common class annotated with ControllerAdvice. Below is a snippet for reference,
#ControllerAdvice
public class CustomizedExceptionHandler extends ResponseEntityExceptionHandler {
#ExceptionHandler(DataAccessException .class)
public final ResponseEntity<ErrorDetails> externalIdmException(DataAccessException ex,
WebRequest request) {
// exception handling
}
}
This Class will catch exceptions of type to which it is defined in a central place. If you want more specific exceptions to be handled at the class level, #ExceptionHandler method can be preferred.