每当发生特定异常时，我都会使用Ed Burns 建议的自定义异常处理程序来显示错误页面。我也尝试在上下文不活动时显示错误页面。但是，这部分（第 45./46 行）会引起麻烦：
nav.handleNavigation(fc, null, "viewExpired");
fc.renderResponse();
完整的 CustomExceptionHandler 来了（如 Ed Burns 在他的博客中建议的那样正确配置）
package com.sun.faces;
import java.util.Iterator;
import java.util.Map;
import javax.enterprise.context.ContextNotActiveException;
import javax.faces.FacesException;
import javax.faces.application.NavigationHandler;
import javax.faces.application.ViewExpiredException;
import javax.faces.component.UIViewRoot;
import javax.faces.context.ExceptionHandler;
import javax.faces.context.ExceptionHandlerWrapper;
import javax.faces.context.FacesContext;
import javax.faces.event.ExceptionQueuedEvent;
import javax.faces.event.ExceptionQueuedEventContext;
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 fc = FacesContext.getCurrentInstance();
Map<String, Object> requestMap = fc.getExternalContext().getRequestMap();
NavigationHandler nav =
fc.getApplication().getNavigationHandler();
try {
// Push some useful stuff to the request scope for
// use in the page
requestMap.put("currentViewId", vee.getViewId());
nav.handleNavigation(fc, null, "viewExpired");
fc.renderResponse();
} finally {
i.remove();
}
}
if (t instanceof ContextNotActiveException) {
FacesContext fc = FacesContext.getCurrentInstance();
NavigationHandler nav =
fc.getApplication().getNavigationHandler();
try {
nav.handleNavigation(fc, null, "contextNotActive");
fc.renderResponse();
} finally {
i.remove();
}
}
}
// At this point, the queue will not contain any exceptions I want to handle (for now).
// Therefore, let the parent handle them.
getWrapped().handle();
}
}
但是，我总是在控制台中打印出“无法呈现视图”。那么为什么它不呈现该错误页面。我认为这是由非活动上下文（由 NavigationHandler 使用）引起的！
任何人都可以确认这种行为吗？
PS：我正在使用 Weld 1.1 和 Mojarra 2.0.4