到目前为止,我遇到的所有ExceptionHandlerFactory
示例都会在捕获ViewExpiredException
时将用户重定向到一个viewExpired.jsf
页面:
public class ViewExpiredExceptionExceptionHandler extends ExceptionHandlerWrapper {
private ExceptionHandler wrapped;
public ViewExpiredExceptionExceptionHandler(ExceptionHandler wrapped) {
this.wrapped = wrapped;
}
@Override
public ExceptionHandler getWrapped() {
return this.wrapped;
}
@Override
public void handle() throws FacesException {
for (Iterator<ExceptionQueuedEvent> i = getUnhandledExceptionQueuedEvents().iterator(); i.hasNext();) {
ExceptionQueuedEvent event = i.next();
ExceptionQueuedEventContext context = (ExceptionQueuedEventContext) event.getSource();
Throwable t = context.getException();
if (t instanceof ViewExpiredException) {
ViewExpiredException vee = (ViewExpiredException) t;
FacesContext facesContext = FacesContext.getCurrentInstance();
Map<String, Object> requestMap = facesContext.getExternalContext().getRequestMap();
NavigationHandler navigationHandler = facesContext.getApplication().getNavigationHandler();
try {
// Push some useful stuff to the request scope for use in the page
requestMap.put("currentViewId", vee.getViewId());
navigationHandler.handleNavigation(facesContext, null, "/viewExpired");
facesContext.renderResponse();
} finally {
i.remove();
}
}
}
// At this point, the queue will not contain any ViewExpiredEvents. Therefore, let the parent handle them.
getWrapped().handle();
}
}
在我看来,下面这个简单的web.xml
配置基本上是相同的,而且更加简单:
<error-page>
<exception-type>javax.faces.application.ViewExpiredException</exception-type>
<location>/viewExpired.jsf</location>
</error-page>
这引发了一个问题-为什么要使用ExceptionHandlerFactory?