JAX-RS Custom ExceptionMapper not intercept RuntimeException

Question

I want to wrap underlaying RuntimeExceptions to a custom json format , making the servlet container won't dump the stacktrace to client.

I follow this question : JAX-RS (Jersey) custom exception with XML or JSON . When calling :

try {
  doSomething(parameters);
}
catch(RuntimeException e) {
  throw new MyCustomException(500 , e.getMessage() , Status.INTERNAL_SERVER_ERROR);
}

When I intentionally feed wrong parameters (and trigger RuntimeException thrown by doSomething() ) , I didn't see MyCustomExceptionMapper working. Instead , the servlet container dumps :

The RuntimeException could not be mapped to a response, re-throwing to the HTTP container
api.MyCustomException: (underlaying msgs)

The MyCustomExceptionMapper is indeed registered in the javax.ws.rs.core.Application :

  @Override
  public Set<Class<?>> getClasses()
  {
    Set<Class<?>> set = new HashSet<Class<?>>();
    set.add(other classes);
    set.add(MyCustomExceptionMapper.class);
    return set;
  }

What did I miss ?

Thanks a lot !

Environment : JAX-RS , jersey-server 1.5

classes spec :

class MyCustomException extends RuntimeException 
@Provider
class MyCustomExceptionMapper implements ExceptionMapper<MyCustomException>

updated :

I suspect that Application.getClasses() is never called , so I add some println messages :

  @Override
  public Set<Class<?>> getClasses()
  {
    System.out.println("\n\n\n\n ApiConfig getClasses");
  }

And in deed , it's never shown !

I am sure this ApiConfig is in the web.xml :

  <context-param>
    <param-name>javax.ws.rs.core.Application</param-name>
    <param-value>destiny.web.api.ApiConfig</param-value>
  </context-param>

But why it seems Jersey never calls it ?

Answer 1

I found the solution.

All I have to do is annotate MyCustomExceptionMapper with Spring's @Repository.

And remove the section in web.xml (not needed)

  <context-param>
    <param-name>javax.ws.rs.core.Application</param-name>
    <param-value>destiny.web.api.ApiConfig</param-value>
  </context-param>

Because Spring will lookup all @Repository and find a @Provider , and Jersey will make use of it.

Answer 2

I think (on the basis of my experiments) that exception providers are looked up by exact class match, rather than by inheritance match, so an exception provider that handles RuntimeException will only fire if the app throws a raw RuntimeException; that's not the case with the class you've showed us. I have some theories about how to fix this (e.g., with a custom filter handler, or possibly some use of AOP) but nothing final yet.

In relation to the second half of your question, I just don't know. What I do know is that Apache CXF (the JAX-RS implementation I've worked with) has/had some failings in this area, and that I thus stick to registering all my @Providers by hand in the app's Spring config. I offer that as experience…