如何在开发人员模式下而非生产环境中调用默认错误页面（Play Framework 2.3.4-Java）

Question

Following the docs I was able to implement custom error handlers in my application by overriding methods in the GlobalSettings class:

@Override
public Promise<Result> onBadRequest(RequestHeader request, String error) {
    return Promise.<Result> pure(Results.notFound(com.me.project.views.html.pages.ErrorPage
            .render(Constants.HTTP_400)));
}

@Override
public Promise<Result> onHandlerNotFound(RequestHeader request) {
    return Promise.<Result> pure(Results.notFound(com.me.project.views.html.pages.ErrorPage
            .render(Constants.HTTP_404)));
}

@Override
public Promise<Result> onError(RequestHeader request, Throwable t) {
    return Promise.<Result> pure(Results.notFound(com.me.project.views.html.pages.ErrorPage
            .render(Constants.HTTP_500)));
}

However I only want these to be used in production and not in development, as the errors being displayed in the browser are quite useful.

I am able to detect whether the application is in dev mode using:

boolen isDev = play.api.Play.isDev(play.api.Play.current());

However I cannot call the default error pages as I do not know how. How do you call the default error pages? I have looked at the code here , but my Scala is poor and I cannot seem to get it working. The parts that I though I should port to java in my global object were:

private def defaultErrorHandler: HttpErrorHandler = {
    Play.maybeApplication.fold[HttpErrorHandler](DefaultHttpErrorHandler) { app =>
        app.injector.instanceOf[DefaultHttpErrorHandler]
    }
}

and

def onError(request: RequestHeader, ex: Throwable): Future[Result] =
    defaultErrorHandler.onServerError(request, ex)

def onHandlerNotFound(request: RequestHeader): Future[Result] =
    defaultErrorHandler.onClientError(request, play.api.http.Status.NOT_FOUND)

def onBadRequest(request: RequestHeader, error: String): Future[Result] =
    defaultErrorHandler.onClientError(request, play.api.http.Status.BAD_REQUEST, error)

But I cannot port this as things like Play.maybeApplication cannot be resoled (are they protected)?!?

I'm sure this should be an easy one but I'm a bit stuck.

Also as a side note can anyone explain the existence of these docs that seem to suggest that the error handling will completely change in 2.4.x :S, I assume that this question will be short lived until 2.4 gets released?

Answer 1

If you browse GlobalSettings.java sources, you will find out, the default implementations of onError(RequestHeader request, Throwable t) and onHandlerNotFound(RequestHeader request) return null, thus you can override these methods this way:

if(Play.isDev()){
    return null;
} else {
    // return promise of result...
}