SimpleJSFNavigationHandler 不能强制转换为 javax.faces.application.ConfigurableNavigationHandler

Question

我正在将一个 JSF 1.2 项目迁移到具有 Ultima 布局的 JSF 2 和 PrimeFaces 6。 使用 Ultima 布局时，出现以下异常：

SimpleJSFNavigationHandler 无法转换为 javax.faces.application.ConfigurableNavigationHandler。

如何解决？

下面是SimpleJSFNavigationHandler。

import java.io.IOException;

import javax.faces.FacesException;
import javax.faces.application.NavigationHandler;
import javax.faces.application.ViewHandler;
import javax.faces.component.UIViewRoot;
import javax.faces.context.ExternalContext;
import javax.faces.context.FacesContext;

import org.springframework.web.jsf.DecoratingNavigationHandler;

public class SimpleJSFNavigationHandler extends DecoratingNavigationHandler {


   public  static final String DEFAULT_REDIRECT_PREFIX = "redirect:";
   public  static final String DEFAULT_FORWARD_PREFIX = "/";

   private String redirectPrefix = DEFAULT_REDIRECT_PREFIX;
   private String forwardPrefix = DEFAULT_FORWARD_PREFIX;

   public SimpleJSFNavigationHandler() {
   }


   public SimpleJSFNavigationHandler(NavigationHandler originalNavigationHandler) {
      super(originalNavigationHandler);
   }

   @Override
   public void handleNavigation(FacesContext facesContext, String fromAction, String outcome, NavigationHandler originalNavigationHandler) {
      if (outcome != null  && outcome.startsWith(redirectPrefix)) {
         ExternalContext externalContext = facesContext.getExternalContext();
         ViewHandler viewHandler = facesContext.getApplication().getViewHandler();
            String url = outcome.substring(redirectPrefix.length());
            String urlParams="";
            if(url.indexOf("?")>0)
               urlParams = url.substring(url.indexOf("?"));
            String redirectPath = viewHandler.getActionURL(facesContext, url);
            try {
               //System.out.println("MMMMMMMMMMMMMMMM:::::::::::::::::" + urlParams);
               externalContext.redirect(externalContext.encodeActionURL(redirectPath+urlParams));

            } catch (IOException e) {
               throw new FacesException(e.getMessage(), e);
            }
            facesContext.responseComplete();
      } else if (outcome != null  && outcome.startsWith(forwardPrefix)) {
         ViewHandler viewHandler = facesContext.getApplication().getViewHandler();
         //create new view
         String newViewId = outcome.substring(forwardPrefix.length());
            if (newViewId.length()>0 && newViewId.charAt(0)!='/') {
               newViewId = "/" + newViewId;
            }
         UIViewRoot viewRoot = viewHandler.createView(facesContext, newViewId);
         viewRoot.setViewId(newViewId);
         facesContext.setViewRoot(viewRoot);
         facesContext.renderResponse();
      } else {
         callNextHandlerInChain(facesContext, fromAction, outcome, originalNavigationHandler);
      }
   }

}

Answer 1

您不需要 Spring 的 DecoratingNavigationHandler。你可以使用 JSF 自己的ConfigurableNavigationHandlerWrapper。

public class SimpleJSFNavigationHandler extends ConfigurableNavigationHandlerWrapper {

    private ConfigurableNavigationHandler wrapped;

    public SimpleJSFNavigationHandler(ConfigurableNavigationHandler wrapped) {
        this.wrapped = wrapped;
    }

    @Override
    public void handleNavigation(FacesContext facesContext, String fromAction, String outcome) {
        if (...) {
            // Your original code here.
        } else if (...) {
            // Your original code here.
        } else {
            // Update only the last else part as below.
            getWrapped().handleNavigation(facesContext, fromAction, outcome);
        }
    }

    @Override
    public ConfigurableNavigationHandler getWrapped() {
        return wrapped;
    }

}

在即将到来的 JSF 2.3 中，这甚至可以根据 spec issue 1429 进一步简化，这将进一步减少 FacesWrapper 实现中的样板代码。

public class SimpleJSFNavigationHandler extends ConfigurableNavigationHandlerWrapper {

    public SimpleJSFNavigationHandler(ConfigurableNavigationHandler wrapped) {
        super(wrapped);
    }

    @Override
    public void handleNavigation(FacesContext facesContext, String fromAction, String outcome) {
        if (...) {
            // Your original code here.
        } else if (...) {
            // Your original code here.
        } else {
            // Update only the last else part as below.
            getWrapped().handleNavigation(facesContext, fromAction, outcome);
        }
    }

}