JSF 2 : Is this a good approach to handle Business exceptions?

Question

按照我之前在 Creating FacesMessage in action method outside JSF conversion/validation mechanism? 中提出的问题，我正在尝试处理从托管 bean 外部的业务层抛出的异常。

该策略是在 PhaseListener 中搜索业务异常并将其转换为面孔消息。

它按我的预期工作，但我只是想知道我是否只是重新发明轮子，或者以错误的方式做正确的事情？

这是我的代码示例片段:

public class BusinessExceptionHandler implements PhaseListener {

    @Override
    public void afterPhase(PhaseEvent phaseEvent) {
        ExceptionHandler exceptionHandler = phaseEvent.getFacesContext().getExceptionHandler();

        // just debugging the handled exception, nothing here
        /*
        for (ExceptionQueuedEvent event : exceptionHandler.getHandledExceptionQueuedEvents()) {
            ExceptionQueuedEventContext context = (ExceptionQueuedEventContext) event.getSource();
            System.out.println("handled exception : " + context.getException());
        }*/

        for (Iterator<ExceptionQueuedEvent> it = exceptionHandler.getUnhandledExceptionQueuedEvents().iterator(); 
                it.hasNext();) {

            ExceptionQueuedEvent event = it.next();
            ExceptionQueuedEventContext eventContext = (ExceptionQueuedEventContext) event.getSource();
            Throwable e = eventContext.getException();
            System.out.println("unhandled exception : " + e);

            // get the root cause exception
            while (e.getCause() != null) { 
                e = e.getCause();
            }

            System.out.println("cause exception : " + e + 
                ", cause exception is BE : " + (e instanceof BusinessException));

            // handle BE
            if (e instanceof BusinessException) {
                BusinessException be = (BusinessException) e;
                System.out.println("processing BE " + be);
                FacesMessage message = Messages.getMessage(
                    "com.corejsf.errors", 
                    be.getMessage(), 
                    be.getParamValues()
                );
                FacesContext context = FacesContext.getCurrentInstance();
                context.addMessage(null, message);
                it.remove(); // remove the exception

                // works fine without this block, if BE is thrown, always return to the original page
                /*
                NavigationHandler navigationHandler = context.getApplication().getNavigationHandler();
                System.out.println("navigating to " + context.getViewRoot().getViewId());
                navigationHandler.handleNavigation(context, context.getViewRoot().getViewId(), null);
                */
            }
        }
    }

    @Override
    public void beforePhase(PhaseEvent phaseEvent) {
    }

    @Override
    public PhaseId getPhaseId() {
        return PhaseId.INVOKE_APPLICATION;
    }

}

谢谢!

问候，金伟强

Answer 1

不知道为什么要走这条路，创建和注册您自己的异常处理程序非常简单。不过 Seam Catch 会更容易( http://seamframework.org/Seam3/CatchModule 和 http://docs.jboss.org/seam/3/catch/3.0.0.Alpha1/reference/en-US/html_single/ )。我还没有 JSF 桥，但它会很容易做到。然后您所要做的就是编写一个方法来处理特定的异常，然后您就完成了!