从preRender导航后无法保留人脸消息 [英] Can't keep faces message after navigation from preRender

问题描述

在我的页面的preRender代码中，我添加面孔消息，然后按如下所示导航到另一个页面:

in my preRender code for a page i add faces message then make navigation to another page as follows:

if(error){
addMessageToComponent(null,"AN ERROR HAS OCCURRED");
FacesContext.getCurrentInstance().getExternalContext().getFlash()
                .setKeepMessages(true);
navigateActionListener("myoutcome");
}

以及用于添加消息和导航的util方法是:

and the util methods for adding message and navigation are:

public static String getClientId(String componentId)
    {
        FacesContext context = FacesContext.getCurrentInstance();
        UIViewRoot root = context.getViewRoot();

        UIComponent c = findComponent(root, componentId);
        return c.getClientId(context);
    }

    public static UIComponent findComponent(UIComponent c, String id)
    {
        if (id.equals(c.getId())) { return c; }
        Iterator<UIComponent> kids = c.getFacetsAndChildren();
        while (kids.hasNext())
        {
            UIComponent found = findComponent(kids.next(), id);
            if (found != null) { return found; }
        }
        return null;
    }

    /**
     * @param componentId
     *            : the id for the jsf/primefaces component without formId:
     *            prefix. <br>
     *            if you use null then the message will be added to the
     *            h:messages component.
     **/
    public static void addMessageToComponent(String componentId, String message)
    {

        if (componentId != null)
            componentId = GeneralUtils.getClientId(componentId);
        FacesContext.getCurrentInstance().addMessage(componentId,
                new FacesMessage(message));
    }

public static void navigateActionListener(String outcome)
    {
        FacesContext context = FacesContext.getCurrentInstance();
        NavigationHandler navigator = context.getApplication()
                .getNavigationHandler();
        navigator.handleNavigation(context, null, outcome);
    }

但是邮件不会保存，因此重定向后不会显示.

but messages are not saved and so it doesn't appear after redirect.

请提出解决方法.

推荐答案

preRenderView事件在RENDER_RESPONSE阶段的最开始运行.指示Flash范围保留消息为时为时已晚.您最多可以在INVOKE_APPLICATION阶段进行此操作.

The preRenderView event runs in the very beginning of the RENDER_RESPONSE phase. It's too late to instruct the Flash scope to keep the messages. You can do this at the latest during the INVOKE_APPLICATION phase.

由于没有标准的JSF组件系统事件，您需要进行自制程序:

Since there's no standard JSF component system event for this, you'd need to homebrew one:

@NamedEvent(shortName="postInvokeAction")
public class PostInvokeActionEvent extends ComponentSystemEvent {

    public PostInvokeActionEvent(UIComponent component) {
        super(component);
    }

}

要发布此内容，您需要PhaseListener:

To publish this, you need a PhaseListener:

public class PostInvokeActionListener implements PhaseListener {

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

    @Override
    public void beforePhase(PhaseEvent event) {
        // NOOP.
    }

    @Override
    public void afterPhase(PhaseEvent event) {
        FacesContext context = FacesContext.getCurrentInstance();
        context.getApplication().publishEvent(context, PostInvokeActionEvent.class, context.getViewRoot());
    }

}

在faces-config.xml中进行如下注册后:

<lifecycle>
    <phase-listener>com.example.PostInvokeActionListener</phase-listener>
</lifecycle>

您将可以按以下方式使用新事件:

You'll be able to use the new event as follows:

<f:event type="postInvokeAction" listener="#{bean.init}" />

您只需要确保您至少具有<f:viewParam>，否则JSF根本不会进入调用的阶段.

You only need to make sure that you've at least a <f:viewParam>, otherwise JSF won't enter the invoked phase at all.

JSF实用程序库 OmniFaces 已经支持该事件，而preInvokeAction事件则是现成的.另请参见展示页面，该页面还演示了设置面部消息以进行重定向.

The JSF utility library OmniFaces already supports this event and the preInvokeAction event out the box. See also the showcase page which also demonstrates setting a facesmessage for redirect.

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